New+Chapter+Two

Life’s Chemical Basis BIOL 160: General Biology

PG.13 Erma Definition Worksheet #2: Chapter 2 Define the following key terms. 1. Atom- Particles that are the building blocks of all substances 2. Proton- positively charged subatomic particules in the nucleus of all atoms 3. Neutron-non-charged subatomic particles in the nucleus of all atoms 4. Electron-negative charged subatomic in the nucleus of all atoms 5. Atomic Number- the difference in the number of subatomic particles, the number of protons 6. Atomic Mass-the number that identifies the element and the number of protons in the element <span style="font-family: Arial,Helvetica,sans-serif;">7. Isotope-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">elements occur in different forms <span style="font-family: Arial,Helvetica,sans-serif;">8. Ion-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">and atom with a different number of electrons and protons <span style="font-family: Arial,Helvetica,sans-serif;">9. Cation- <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">positive charged ions <span style="font-family: Arial,Helvetica,sans-serif;">10. Anion- <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">negative charged ions <span style="font-family: Arial,Helvetica,sans-serif;">11. Molecule-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">group of two or more atoms joined by chemical bond <span style="font-family: Arial,Helvetica,sans-serif;">12. Chemical Bond-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">an attractive force that arises between two atoms when their electrons interact <span style="font-family: Arial,Helvetica,sans-serif;">13. Ionic Bond-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">the strong mutual attraction between of two oppositely charged ions <span style="font-family: Arial,Helvetica,sans-serif;">14. Electronegativity-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">is the measure of an atoms ability to pull electrons from other atoms <span style="font-family: Arial,Helvetica,sans-serif;">15. Polar Covalent Bond- <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">atom particles that do not share electrons equally <span style="font-family: Arial,Helvetica,sans-serif;">16. Non-polar Covalent Bond-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">means the atom particles in the bond are sharing electrons equally <span style="font-family: Arial,Helvetica,sans-serif;">17. Hydrogen Bond-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">a weak attraction between highly elecronegative atom and hydrogen <span style="font-family: Arial,Helvetica,sans-serif;">18. Solution-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">a homogeneous mixture composed of two or more sustances <span style="font-family: Arial,Helvetica,sans-serif;">19. Solute-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">dissolved substance <span style="font-family: Arial,Helvetica,sans-serif;">20. Solvent-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">liquid substance that can dissolve other substances <span style="font-family: Arial,Helvetica,sans-serif;">21. Acid-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">substances that donate hydrogen ions as they dissolve <span style="font-family: Arial,Helvetica,sans-serif;">22. Base- <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">substance that accepts hydrogen ions <span style="font-family: Arial,Helvetica,sans-serif;">23. Buffer-<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">a set of chemicals, often a weak acid or base that can keep the PH of a solution stable <span style="font-family: Arial,Helvetica,sans-serif;">24. Salt -- a compound that dissolves easily in water and releases ions other then hydrogen or hydroxide ions

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 14 <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Erma <span style="font-family: Arial,Helvetica,sans-serif;">CHAPTER 2: Basic Introduction to Chemistry <span style="font-family: Arial,Helvetica,sans-serif;">Characteristics of atoms proton +1 Nucleus 1 AMU Neuron 0 Nucleus 1 AMU Electron -1 Outside Nucleus Negligible
 * Subatomic Particle Charge Location Mass**

<span style="font-family: Arial,Helvetica,sans-serif;">Recent discoveries have increased the number of naturally occurring elements from 92 to 94.

<span style="font-family: Arial,Helvetica,sans-serif;">Since subatomic particles may be charged, they may attract or repel other subatomic particles. Please complete the below table, indicating how the below pairings of subatomic particles would behave (attract, neutral, repulsion).


 * = <span style="font-family: Arial,Helvetica,sans-serif;">Subatomic particle ||= <span style="font-family: Arial,Helvetica,sans-serif;">Proton ||= <span style="font-family: Arial,Helvetica,sans-serif;">Neutron ||= <span style="font-family: Arial,Helvetica,sans-serif;">Electron ||
 * = <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Proton ||= <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">repulsion ||= Netral ||= attraction ||
 * = <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Neutron ||= nuetral ||= <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Neutral ||= neutral ||
 * = <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Electron ||= <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">attraction ||= netral ||= repulsion ||

<span style="font-family: Arial,Helvetica,sans-serif;">What is an element? Am element is a fundamental substance made by only one kind of atom

<span style="font-family: Arial,Helvetica,sans-serif;">2. Periodic Table <span style="font-family: Arial,Helvetica,sans-serif;">The periodic table of elements has elements placed in a repeating pattern <span style="font-family: Arial,Helvetica,sans-serif;">based on their chemical properties and how they react with other <span style="font-family: Arial,Helvetica,sans-serif;">elements. (Appendix 4 in the back of the book shows a periodic table.)


 * <span style="font-family: Arial,Helvetica,sans-serif;">Principle || <span style="font-family: Arial,Helvetica,sans-serif;">Definition || <span style="font-family: Arial,Helvetica,sans-serif;">C || <span style="font-family: Arial,Helvetica,sans-serif;">N || <span style="font-family: Arial,Helvetica,sans-serif;">O || <span style="font-family: Arial,Helvetica,sans-serif;">P || <span style="font-family: Arial,Helvetica,sans-serif;">Fl || <span style="font-family: Arial,Helvetica,sans-serif;">Na ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Atomic Number || amount of protons in an atom || 6 || 7 || 8 || 15 || 9 || 11 ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Atomic Mass || amount of positive neutrons || 12.011 || 14.007 || 15.999 || 30.794 || 18.998 || 22.99 ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">#of electrons ||  || 6 || 7 || 8 || 15 || 9 || 11 ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">#of protons ||  || 6 || 7 || 8 || 15 || 9 || 11 ||

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 15 <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Erma <span style="font-family: Arial,Helvetica,sans-serif;">3. What makes Carbon different than Hydrogen? the number of protons ,nuetrons and electrons <span style="font-family: Arial,Helvetica,sans-serif;">4. What is an isotope? An isotope is an atom of an element that is different in its number of nuetrons

<span style="font-family: Arial,Helvetica,sans-serif;">A. The element carbon has 3 main different isotopes: <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">12C has a mass of 12, due to **6** protons and **6** neutrons <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">13C has a mass of 13, due to **6** protons and **7** neutrons <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">14C has a mass of 14, due to **6** protons and **8** neutrons <span style="font-family: Arial,Helvetica,sans-serif;">B. Some isotopes have an unstable nucleus and may release energy or some of the subatomic particles (protons or neutrons) to become more stable. These isotopes <span style="font-family: Arial,Helvetica,sans-serif;">are called **radioisotopes**. Some are used in medicine to “label” specific molecules or to follow a specific molecule as it is distributed throughout the body. In this case it is commonly called a **tracer** They may also release enough energy to kill cells and stop the activity of abnormal (cancer) cells, or the energy released may be used to drive an artificial pacemaker (helps the heart maintain a regular rhythm). <span style="font-family: Arial,Helvetica,sans-serif;">5. It is most important to know what the subatomic particles are, where they are located in an atom, and that atoms of different elements differ because they contain different numbers of protons. The number behind each elemental name represents the atomic mass for that atom. Complete the following table.

<span style="font-family: Arial,Helvetica,sans-serif;">PG.16 <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Erma <span style="font-family: Arial,Helvetica,sans-serif;">6. Complete the following matching activity. <span style="font-family: Arial,Helvetica,sans-serif;">A. Radioisotope used to reveal the pathway or destination of a substance <span style="font-family: Arial,Helvetica,sans-serif;">B. Subatomic particles with a negative charge <span style="font-family: Arial,Helvetica,sans-serif;">C. Positively charged subatomic particles within the nucleus <span style="font-family: Arial,Helvetica,sans-serif;">D. Subatomic particles within the nucleus carrying no charge <span style="font-family: Arial,Helvetica,sans-serif;">E. Atoms of a given element that differ in the number of neutrons <span style="font-family: Arial,Helvetica,sans-serif;">F. The number of protons in an atom <span style="font-family: Arial,Helvetica,sans-serif;">G. Form of an element that emits radiation <span style="font-family: Arial,Helvetica,sans-serif;">H. The number of protons and neutrons in the nucleus of one atom <span style="font-family: Arial,Helvetica,sans-serif;">I. Pure substances, each consisting only of atoms with the same number of protons <span style="font-family: Arial,Helvetica,sans-serif;">J. Smallest units of an element that retain the properties of a given element. Particles that are the building blocks of all substances.
 * <span style="font-family: Arial,Helvetica,sans-serif;">Element || <span style="font-family: Arial,Helvetica,sans-serif;">Symbol || <span style="font-family: Arial,Helvetica,sans-serif;">Atomic Number || <span style="font-family: Arial,Helvetica,sans-serif;">Atomic Mass || <span style="font-family: Arial,Helvetica,sans-serif;">Number of Protons || <span style="font-family: Arial,Helvetica,sans-serif;">Number of Neutrons || <span style="font-family: Arial,Helvetica,sans-serif;">Number of Electrons ||
 * <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Nitrogen-14 || N || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">7 || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">14 || 7 || 7 || 7 ||
 * <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Chlorine-35 || CI || 17 || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">35 || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">17 || 18 || 17 ||
 * <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Oxygen-16 || O || 8 || 16 || 8 || 8 || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">8 ||
 * <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Sodium-23 || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Na || 11 || 22.9 || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">11 || 12 || 11 ||
 * <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Sulfur-35 || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">S || 16 || <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">35 || 16 || 19 || 16 ||
 * <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">Oxygen-17 || O || 8 || 7 || 8 || 9 || 8 ||

<span style="font-family: Arial,Helvetica,sans-serif;">1. atoms ............ <span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**J** <span style="font-family: Arial,Helvetica,sans-serif;">2. protons............<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**C** <span style="font-family: Arial,Helvetica,sans-serif;">3. neutrons..........<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**D** <span style="font-family: Arial,Helvetica,sans-serif;">4. electrons..........<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**B** <span style="font-family: Arial,Helvetica,sans-serif;">5. atomic number.<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**F** <span style="font-family: Arial,Helvetica,sans-serif;">6. atomic mass.....<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**H** <span style="font-family: Arial,Helvetica,sans-serif;">7. elements...........<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**I** <span style="font-family: Arial,Helvetica,sans-serif;">8. isotope.............<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**E** <span style="font-family: Arial,Helvetica,sans-serif;">9. radioisotopes...<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**G** <span style="font-family: Arial,Helvetica,sans-serif;">10. tracer.............<span style="color: #ff00ff; font-family: Arial,Helvetica,sans-serif;">**A**

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 17 <span style="font-family: Arial,Helvetica,sans-serif;">7. Chemical Bonds <span style="font-family: Arial,Helvetica,sans-serif;">Which subatomic particle participates in bonding between atoms? <span style="font-family: Arial,Helvetica,sans-serif;">protons and neutrons <span style="font-family: Arial,Helvetica,sans-serif;">How do you figure out how many electrons there are in an atom? protons=electrons

<span style="font-family: Arial,Helvetica,sans-serif;">B. Each horizontal row on the periodic table represents an energy level around the nucleus of an atom.

<span style="font-family: Arial,Helvetica,sans-serif;">1.The first level is closest to the nucleus and can hold only 2 electrons due <span style="font-family: Arial,Helvetica,sans-serif;">to its small volume and the fact that electrons repel each other. Electrons in this level have the lowest amount of energy. Notice that the top row on the periodic table has only two elements (H and He) and the atomic number of Helium is 2 which means it has 2 protons and 2 electrons.

<span style="font-family: Arial,Helvetica,sans-serif;">2. The second level is farther away from the nucleus, so is larger in volume and can hold a maximum of 8 electrons. Notice that the second row on the periodic table has a total of eight elements and the atomic number for Neon the last element on the row is 10; which means a neutral Neon atom has 10 protons and 10 electrons (two of the electrons are on the first energy level and the remaining 8 electrons on the second level).

<span style="font-family: Arial,Helvetica,sans-serif;">3. The third level is still farther away from the nucleus, so is able to hold more electrons than the second level, and the fourth level more than the third, etc. The problem is that not all of these additional electrons are located on the outermost energy level.

<span style="font-family: Arial,Helvetica,sans-serif;">C. The atomic number on the periodic table equals the total number of protons inside the nucleus and therefore the total number of electrons found moving around the nucleus in an atom; however it is only those electrons on the outer energy level that are taken, shared or given away when atoms interact with other atoms. The maximum number of electrons that can exist on the outer energy level of any atom is ALWAYS eight (except for H and He where the maximum number is two). Try to remember that “eight is great”. For the purposes of this class and to best prepare you for Anatomy and Physiology, it is necessary to “simplify” chemistry and the periodic table. It will be easier to understand how atoms behave if you pretend that the center (and bottom) of the periodic table don’t exist. Those elements in the middle of the periodic table have additional electrons that are NOT placed in the outer most energy level, therefore they do NOT influence how an atom of that element behaves.

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 18 <span style="font-family: Arial,Helvetica,sans-serif;">If this is the case, then all of the horizontal rows on the table will have eight columns, except the first horizontal row which will have only two columns. <span style="font-family: Arial,Helvetica,sans-serif;">D. Where the elements are found on the periodic table will help determine how an atom will interact with other atoms (“take”, “share” or “give away” some of their electrons). The vertical column of the periodic table indicates the number of electrons an atom of that element has in the outermost energy level. As mentioned, it is only these outermost electrons that will influence how an atom interacts with other atoms as they form molecules. <span style="font-family: Arial,Helvetica,sans-serif;">E. Those elements in the last column on the periodic table (farthest to the right, or in column #8) are the most “stable” of all the elements, having just the right number of electrons to “fill” the outer energy level. These elements are very stable and normally do not react chemically with the other elements to form molecules. (Called the Inert Gases) <span style="font-family: Arial,Helvetica,sans-serif;">F. All the other elements on the periodic table “wish” they could have the same number of electrons as one of those in column #8 (farthest to the right) so they too can become very stable. They do this by taking, giving or sharing electrons to fill their outer electron shell. <span style="font-family: Arial,Helvetica,sans-serif;">The ability of an atom to “pull or take” electrons from another atom to become more stable is called ELECTRONEGATIVITY. <span style="font-family: Arial,Helvetica,sans-serif;">1. Those elements on the right side of the periodic table are so close to the last column, they tend to have high electronegativity values and tend to “TAKE” electrons from other elements until they have a total of 8 in their outer energy level or in some cases they may be forced to share electrons with other atoms. Using the periodic table as a guide, how many more electrons do atoms of the following elements need to take or share to reach a total of those in the last column? <span style="font-family: Arial,Helvetica,sans-serif;">P = 3, Cl = 1, O =2, N =3 , S =2 , C =4 , Br =1

<span style="font-family: Arial,Helvetica,sans-serif;">2. Those elements on the left side of the periodic table are far away from the last column, they tend to have very low electronegativity values and do NOT “pull or take” electrons from other atoms, in fact they tend to “GIVE AWAY” their electrons that are on the outer energy level to other atoms. In a sense they go backwards on the table until they reach the last column but on the row above where they started. Using the periodic table as a guide, how many electrons do atoms of the following elements need to give away or lose to revert back to the end of the previous level on the periodic table? <span style="font-family: Arial,Helvetica,sans-serif;">Na =0, Al = 3, Ca =2 , K =0 , C =4 , Mg = 2

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 19 <span style="font-family: Arial,Helvetica,sans-serif;">G. Neutral atoms that “take” or “give away” electrons no longer remain neutral; they <span style="font-family: Arial,Helvetica,sans-serif;">become either negatively or positively charged particles called ions. There are two main types:

<span style="font-family: Arial,Helvetica,sans-serif;">1. ANIONS are those that have a negative charge because the neutral atom has “taken” electrons from other atoms so they now have more electrons than protons.

<span style="font-family: Arial,Helvetica,sans-serif;">2. CATIONS are those that have a positive charge because the neutral atom has “given away” electrons to other atoms so they now have fewer electrons than protons.

<span style="font-family: Arial,Helvetica,sans-serif;">8. When atoms “give away”,” take” or “share” electrons with other atoms they form a <span style="font-family: Arial,Helvetica,sans-serif;">CHEMICAL bond (a force between two atoms that holds them together).

<span style="font-family: Arial,Helvetica,sans-serif;">A. molecules are two or more atoms that have joined together to form a group. Some only contain one type of element: H2, O2, N2, F2, Cl2, Br2 & I2, but the majority contain two or more different types of elements. When a molecule contains two or more different elements combined in a fixed ratio (proportion) that never varies it is called a compound. Examples include: water (H2O), Carbon dioxide (CO2), Hydrochloric acid (HCl), and Glucose (C6H12O6). The numbers in the chemical formulas indicate the number of atoms of each type in the molecule.

<span style="font-family: Arial,Helvetica,sans-serif;">B. mixtures contain two or more substances (elements or compounds) that are combined together in a ratio (proportion) that varies. They can either be concentrated or dilute (as in strong or weak coffee). These forms of matter will be studied in much more detail in future modules.

<span style="font-family: Arial,Helvetica,sans-serif;">9. There are several important chemical bonds seen in biological molecules.

<span style="font-family: Arial,Helvetica,sans-serif;">A.IONIC BONDS: oppositely charged ions held close by attraction, electrons transferred (one loses, one gains) between atoms


 * <span style="font-family: Arial,Helvetica,sans-serif;">Element Location || <span style="font-family: Arial,Helvetica,sans-serif;">Giver? Taker? || <span style="font-family: Arial,Helvetica,sans-serif;">What type of ion formed? || <span style="font-family: Arial,Helvetica,sans-serif;">Positive or negatively charged ion? ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Left side of per table || giver || cations || positive ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Right side of per. table || taker || anions || negative ||

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 20 <span style="font-family: Arial,Helvetica,sans-serif;">1. Chemical formulas represent the type and number of atoms present in the compound. The number of atoms needed to keep the molecule neutral is dependent on the ion charges. Elements that “give away” one electron form +1 ions, those that “give away” 2 electrons form +2 ions, etc. Elements that “take” one electron form -1 ions, those that “take” 2 electrons form -2 ions, etc. Some examples of chemical formulas for ionic compounds include: <span style="font-family: Arial,Helvetica,sans-serif;">Sodium chloride: NaCl This compound contains Na+1 and Cl-1 ions in a 1:1 ratio since their ion charges are the same value (+1 / -1) and they cancel each other out when forming a neutral atom. <span style="font-family: Arial,Helvetica,sans-serif;">Magnesium nitride: Mg3N2 This compound contains Mg+2 and N-3 ions in a 3:2 ratio since their ion charges do not directly cancel each other out; three Mg+2 ions are needed to make a total of +6 charge, which is cancelled out by two N-3 ions that make a total of -6 charge forming a neutral molecule. <span style="font-family: Arial,Helvetica,sans-serif;">B. COVALENT BONDS: <span style="font-family: Arial,Helvetica,sans-serif;">1. What is a covalent bond? It is a bond that holds atoms together, they share a pair of electrons <span style="font-family: Arial,Helvetica,sans-serif;">2. Atoms with (similar, differing) electronegativities form covalent bonds. <span style="font-family: Arial,Helvetica,sans-serif;">PG. 21 <span style="font-family: Arial,Helvetica,sans-serif;">3. Covalent bonds are the strongest type of all chemical bonds. They are very difficult to break, and hold atoms together to form molecules. These bonds are also called INTRAMOLECULAR forces, because they exist within the molecule.
 * <span style="font-family: Arial,Helvetica,sans-serif;">Covalent Bond || <span style="font-family: Arial,Helvetica,sans-serif;"># of electrons shared? || <span style="font-family: Arial,Helvetica,sans-serif;">Example || <span style="font-family: Arial,Helvetica,sans-serif;">Structural Formula || <span style="font-family: Arial,Helvetica,sans-serif;">Strength ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Single || 2 || Hydrogen ||  || <span style="font-family: Arial,Helvetica,sans-serif;">Strong ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Double || 4 || Oxygen ||  || <span style="font-family: Arial,Helvetica,sans-serif;">Stronger ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Triple || 6 || Nitrogen ||  || <span style="font-family: Arial,Helvetica,sans-serif;">Stronger yet! ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Between two identical atoms || <span style="font-family: Arial,Helvetica,sans-serif;">2 || <span style="font-family: Arial,Helvetica,sans-serif;">H2 ||  || <span style="font-family: Arial,Helvetica,sans-serif;">NONPOLAR Covalent Bond ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Between two different atoms || <span style="font-family: Arial,Helvetica,sans-serif;">4 || <span style="font-family: Arial,Helvetica,sans-serif;">H2O ||  || <span style="font-family: Arial,Helvetica,sans-serif;">POLAR ||

<span style="font-family: Arial,Helvetica,sans-serif;">4. Chemical formulas of compounds that have covalent bonds are determined much the same way that ionic compounds are determined; however both atoms want to “take” electrons from each other. The number of atoms needed to keep the molecule neutral is dependent on the number of electrons they need to be like elements in column #8 on the periodic table. Some examples of chemical formulas for covalent compounds include:


 * <span style="font-family: Arial,Helvetica,sans-serif;">Water (H2O) || <span style="font-family: Arial,Helvetica,sans-serif;"># of e-s in outer shell || <span style="font-family: Arial,Helvetica,sans-serif;">What combo would form an outer shell with 8 e-s? || <span style="font-family: Arial,Helvetica,sans-serif;">Draw molecule ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Hydrogen || **1** || Hydrogen only needs one more to fill outer shell || <span style="font-family: Arial,Helvetica,sans-serif;">[[image:http://t0.gstatic.com/images?q=tbn:FOdEmt2JnkYSsM:http://sbcb.bioch.ox.ac.uk/oliver/images/water.png caption="external image water.png"]] ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Oxygen || **6** || Oxygen + 2 others with single bonds, or one with a double bond ||  ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Carbon Dioxide (CO2) || <span style="font-family: Arial,Helvetica,sans-serif;"># of e-s in outer shell || <span style="font-family: Arial,Helvetica,sans-serif;">What combo would form an outer shell with 8 e-s? || <span style="font-family: Arial,Helvetica,sans-serif;">Draw molecule ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Carbon || **4** || C + 2 oxygen single bonds ||  || <span style="font-family: Arial,Helvetica,sans-serif;">[[image:http://t3.gstatic.com/images?q=tbn:iUFLZRwzAP7f6M:http://www.tennoji-h.oku.ed.jp/tennoji/oka/2004/carbon%20dioxide.gif caption="See full size image" link="http://www.tennoji-h.oku.ed.jp/tennoji/oka/2004/carbon%20dioxide.gif"]] ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">See full size image ||  ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">Oxygen || **6** || 2 O bonded to C with single bonds ||  ||

<span style="font-family: Arial,Helvetica,sans-serif;">C. HYDROGEN BONDS: <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">1. What is a hydrogen bond? -

A weak intermolecular attraction between hydrogen and a nearby strongly electronegative element such as Oxygen, Nitrogen or Fluorine

<span style="font-family: Arial,Helvetica,sans-serif;">2. Are hydrogen bonds weak or strong attractions? - BY themselves, they are weak, but collectively can be very strong attractions.

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 22 <span style="font-family: Arial,Helvetica,sans-serif;">10. Water’s Life-Giving Properties <span style="font-family: Arial,Helvetica,sans-serif;">This illustration shows how hydrogen bonds collectively stabilize water molecules. How does this affect the unique physical properties of water?

<span style="font-family: Arial,Helvetica,sans-serif;">a. Water is a molecule held together with POLAR COVALENT BONDS. Draw a picture of a water molecule, and explain how the oxygen and hydrogens participate in this type of bond.

See water above Since there are many more electrons in the region of the oxygen, this area of the water is partially negative; the areas where there are hydrogens are partially positive. Since there are areas of partially positive and negative charges on the molecule, it is said to have poles or be POLAR. The areas of positive and negative charge accumulation are attracted to molecules or ions nearby with opposite charges (for example, oxygen on one water is attracted to hydrogen on another water molecule).

<span style="font-family: Arial,Helvetica,sans-serif;">b. Which part of a water molecule is slightly negative? **Oxygen Atom**

<span style="font-family: Arial,Helvetica,sans-serif;">c. Which is partially positive? **Hydrogen Atoms**

<span style="font-family: Arial,Helvetica,sans-serif;">d. How does this affect interaction with other nearby molecules of water? Or other types of molecules?

<span style="font-family: Arial,Helvetica,sans-serif;">e.Why does water have such a high surface tension?

The water molecules form hydrogen bonds with each other, and collectively they are very strong. It is hard to pull apart the water molecules. Water is a molecule with polar covalent bonds within its structure, and hydrogen bonds between neighboring water molecules. This makes a strong structure that is hard to change.

<span style="font-family: Arial,Helvetica,sans-serif;">f. What is a solvent?

<span style="font-family: Arial,Helvetica,sans-serif;">**A substance, usually liquid, that can dissolve other substances**

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 23 <span style="font-family: Arial,Helvetica,sans-serif;">g. Why is water such a good solvent?

Due to its polar covalent nature, it can form a sphere of hydration around a lot of charged substances and dissolve them.

<span style="font-family: Arial,Helvetica,sans-serif;">Positive ions attract the negative part of <span style="font-family: Arial,Helvetica,sans-serif;">part of water (the **Oxygen** atom), <span style="font-family: Arial,Helvetica,sans-serif;">while negative ions attract the positive part <span style="font-family: Arial,Helvetica,sans-serif;">of water (the **Hydrogen** atoms). <span style="font-family: Arial,Helvetica,sans-serif;">h. Water’s Temperature-Stabilizing Effects: <span style="font-family: Arial,Helvetica,sans-serif;">What is temperature? **A way to measure the energy of molecular motion**

<span style="font-family: Arial,Helvetica,sans-serif;">Why is it hard to change the temperature of water? **Hydrogen Bonding resists "jiggling" of water molecules**

<span style="font-family: Arial,Helvetica,sans-serif;">i. Water’s Cohesion: <span style="font-family: Arial,Helvetica,sans-serif;">What is cohesion? **Molecules resist separating from each other**

<span style="font-family: Arial,Helvetica,sans-serif;">How does the cohesion of water molecules help transport water up inside of the tissues of plants?

<span style="font-family: Arial,Helvetica,sans-serif;">11. Dissolved ions inside of our bodies influence its structure and function. One of the body’s most chemically active ion is the hydrogen ion (H+1).

<span style="font-family: Arial,Helvetica,sans-serif;">A. **Acids** are substances that release or donate hydrogen ions (H+1) to a water (aqueous) solution. Remember that a hydrogen ion is the same thing as a proton since it is a hydrogen atom that has lost its electron.

<span style="font-family: Arial,Helvetica,sans-serif;">1. Strong acids ionize completely releasing their hydrogen ions easily. One example is Hydrochloric acid (HCl) found in the stomach.

<span style="font-family: Arial,Helvetica,sans-serif;">2. Weak acids may have hydrogen ions to release to solution, but are reluctant or resistant to do so. One example is Carbonic acid (H2CO3) found in soft drinks that is formed when carbon dioxide reacts with water.

<span style="font-family: Arial,Helvetica,sans-serif;">B. **Bases** are substances that accept or bond with hydrogen ions when dissolved in water solutions, thereby removing them or decreasing the number of hydrogen ions remaining in solution. They may also release hydroxide ions (OH-1) to a solution that will then combine with hydrogen ions to form water. These solutions are also known as alkaline solutions. This is how Alka Seltzer got its name. It reduces the acidity of the stomach when someone has acid indigestion.

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 24 <span style="font-family: Arial,Helvetica,sans-serif;">C. The **pH** SCALE is used by scientists to represent the nature of a solution relative to the amount of hydrogen ions in solution. The scale extends from a numerical value of **1** to **14**. <span style="font-family: Arial,Helvetica,sans-serif;">1. Solutions with a value of “0” are very **acidic**, meaning there is a high concentration of hydrogen ions in solution. <span style="font-family: Arial,Helvetica,sans-serif;">2. Solutions with a value of “14” are very **basic** (alkaline), <span style="font-family: Arial,Helvetica,sans-serif;">meaning there is a very low concentration of hydrogen ions in solution. <span style="font-family: Arial,Helvetica,sans-serif;">3. Pure water has a value of “**7**”, which indicates it is a neutral solution, or in other words one with the same amount of H+1 and OH-1 ions. <span style="font-family: Arial,Helvetica,sans-serif;">4. The pH scale is a type of metric scale. This means that for every change in the pH, there is a ten-fold change in the concentration of hydrogen ions. On the metric scale, to change from one unit of measurement to another it is necessary to move the decimal point either to the right or to the left. Each time the decimal point is moved it is equal to multiplying or dividing by 10. If the decimal moves 3 places to the right it is equal to multiplying the value by 10 X 10 X 10 or the final answer is 1,000 times larger. The following are several examples: <span style="font-family: Arial,Helvetica,sans-serif;">A solution with a pH = 2 is 10 times more acidic than a solution of pH = 3. <span style="font-family: Arial,Helvetica,sans-serif;">A solution with a pH = 5 is 100 times less acidic than a solution of pH = 3. <span style="font-family: Arial,Helvetica,sans-serif;">A solution with a pH = 10 is 100 times more basic than a solution of pH = 8. <span style="font-family: Arial,Helvetica,sans-serif;">A solution with a pH = 6 is 1000 times less basic than a solution of pH = 9. <span style="font-family: Arial,Helvetica,sans-serif;">D. _**salts** are substances that when dissolved in water release ions other than the hydrogen ion (H+1) or hydroxide ion (OH-1). Examples include sodium chloride or table salt (NaCl) and calcium phosphate [ Ca3(PO4)2 ] found in bones. Most salts serve key functions in cells. The ions released into solution in the body are also called “electrolytes”, in that they allow the solution to be able to conduct an electric current. <span style="font-family: Arial,Helvetica,sans-serif;">E. _**buffers** are substances that resist a change in pH when an acid or base is added to the solution. They are generally formed by mixing a weak acid and weak base. If a strong acid is added to the mixture, the weak base bonds to the hydrogen ions to neutralize the acid; if a strong base is added to the mixture, the weak acid releases hydrogen ions to neutralize the base. In either case, the pH does not change significantly. <span style="font-family: Arial,Helvetica,sans-serif;">Buffers can only work for so long, then the pH will shift rapidly.

<span style="font-family: Arial,Helvetica,sans-serif;">12. Give the approximate pH of each of the following solutions then identify each as an acid (A) [pH of 1-6], base (B) [ph of 8-14] or essentially neutral (N) [pH of 6-8].

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 25 <span style="font-family: Arial,Helvetica,sans-serif;">1. Tomato juice _ **pH 4.0 - A** <span style="font-family: Arial,Helvetica,sans-serif;">2. Human blood _ **pH 7.0 - N** <span style="font-family: Arial,Helvetica,sans-serif;">3. Vinegar _ **pH 3.0 - A** <span style="font-family: Arial,Helvetica,sans-serif;">4. Pure water _ **pH 7.0 - N** <span style="font-family: Arial,Helvetica,sans-serif;">5. Coffee _ **pH 5.0 - A** <span style="font-family: Arial,Helvetica,sans-serif;">6. Ammonia _ **pH 10.0 - B** <span style="font-family: Arial,Helvetica,sans-serif;">7. Seawater _ **pH 8.0 - B** <span style="font-family: Arial,Helvetica,sans-serif;">8. Typical rainwater _ **pH 4.0 - A** <span style="font-family: Arial,Helvetica,sans-serif;">9. Oven / Drain cleaner _ **pH 13.5 - B** <span style="font-family: Arial,Helvetica,sans-serif;">10. Antacid pills (Tums) _ **pH 8.0 - B** <span style="font-family: Arial,Helvetica,sans-serif;">11. Urine _ **pH 4.0 - A** <span style="font-family: Arial,Helvetica,sans-serif;">12. Gastric juice _ **pH 1.0 - A**

<span style="font-family: Arial,Helvetica,sans-serif;">PG. 27 (there is no pg. 26) <span style="font-family: Arial,Helvetica,sans-serif;">13. Complete the following matching

1. Acid stomach - **N. Can be caused by eating too much fried chicken or certain other foods** 2. Acids - **K. Substances that donate H+ when dissolved in water** 3. pH scale - **F. Used to measure H+ concentration in various fluids** 4. Chemical burns - **J. Can be caused by ammonia, drain cleaner, and sulfuric acid in car batteries** 5. H+ - **H. Hydrogen ion or proton** 6. Bases - **D. Substances that accept H+ when dissolved in water** 7. Examples of basic solutions - **I. Baking soda, seawater, egg white** 8. Coma - **A. A sometimes irreversible state of unconsciousness** 9. Respiratoryacidosis - **B. CO2 builds up in the blood, too much H2CO3 forms, and blood pH severely decreases** 10. OH– - **C. Hydroxide ion** 11. Tetany - **M. A potentially lethal pH stage in which the body’s skeletal muscles enter a state of uncontrollable contraction** 12. Examples of acid solutions - **L. Lemon juice, gastric fluid, coffee** 13. Alkolosis - **E. An uncorrected increase in blood pH** 14. Buffer system - **G. A partnership between a weak acid and the base that forms when it dissolves in water; counters slight pH shifts**

<span style="font-family: Arial,Helvetica,sans-serif;">PG.29 <span style="font-family: Arial,Helvetica,sans-serif;">Chapter review: Answer the following essay questions.

<span style="font-family: Arial,Helvetica,sans-serif;">14. a. If a sulfur atom has six electrons in its outer shell of electrons, how many covalent bonds is it likely to form with other atoms? Why? 2 Because it needs 8 electrons in the outer shell to be stable

<span style="font-family: Arial,Helvetica,sans-serif;">b. If a hydrogen atom has one electron in its outer shell of electrons, how many covalent bonds is it likely to form with other atoms? Why? 1 Because it needs 2 electrons in outer shell to be stable.

<span style="font-family: Arial,Helvetica,sans-serif;">c. What do you think the chemical formula for hydrogen sulfide would be? <span style="font-family: Arial,Helvetica,sans-serif;">Hint: Look at the location of sulfur compared to oxygen on the periodic table. H1S1

<span style="font-family: Arial,Helvetica,sans-serif;">15. In your own words, explain the main difference between a polar covalent bond and a nonpolar covalent bond. Nonpolar covalent bonds share electrons equally and there is not a difference in charge. Polar covalent bonds do NOT share electrons equally. Whichever atom has more electronegative pull has a little bit of a negative charge. The other atom is positive. <span style="font-family: Arial,Helvetica,sans-serif;">PG. 30 <span style="font-family: Arial,Helvetica,sans-serif;">16. If a water molecule is neutral (has no net charge), then why does it attract polar molecules and repel nonpolar ones. Because polar covalent bonds are hydrophyllic.

<span style="font-family: Arial,Helvetica,sans-serif;">17. Explain why sweating helps cool the body when it is overheated? When overheated, heat energy converts liquid water to gas, so the surface temperature of water decreases during evaporation. Your sweat is about 99% water that cools the skin as it evaporates.

<span style="font-family: Arial,Helvetica,sans-serif;">Sample Test Questions for chapter 2 and Lab #6: <span style="font-family: Arial,Helvetica,sans-serif;">1. A substance that cannot be broken down into simpler substances by ordinary <span style="font-family: Arial,Helvetica,sans-serif;">chemical means is known as a(n) <span style="font-family: Arial,Helvetica,sans-serif;">a. molecule <span style="font-family: Arial,Helvetica,sans-serif;">b. ion c. element <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">d. compound <span style="font-family: Arial,Helvetica,sans-serif;">e. isotope

<span style="font-family: Arial,Helvetica,sans-serif;">2. A sulfur atom has 6 electrons in its outer energy shell. As a result, it tends to form <span style="font-family: Arial,Helvetica,sans-serif;">covalent bonds with other atoms. <span style="color: #800080; font-family: Arial,Helvetica,sans-serif;">a. 2 <span style="font-family: Arial,Helvetica,sans-serif;">b. 3 <span style="font-family: Arial,Helvetica,sans-serif;">c. 4 <span style="font-family: Arial,Helvetica,sans-serif;">d. 6 <span style="font-family: Arial,Helvetica,sans-serif;">e. 8

<span style="font-family: Arial,Helvetica,sans-serif;">3. A phosphorus atom has an atomic mass (mass number) of 31 and an atomic number of 15. How many PROTONS are ther ina neutral phosphorus atom? <span style="color: #800080; font-family: Arial,Helvetica,sans-serif;">a. 15 <span style="font-family: Arial,Helvetica,sans-serif;">b. 16 <span style="font-family: Arial,Helvetica,sans-serif;">c. 31 <span style="font-family: Arial,Helvetica,sans-serif;">d. 46 <span style="font-family: Arial,Helvetica,sans-serif;">e. none of the above

<span style="font-family: Arial,Helvetica,sans-serif;">4. A is a subatomic particle that caries a charge. <span style="font-family: Arial,Helvetica,sans-serif;">a. proton......negative <span style="color: #800080; font-family: Arial,Helvetica,sans-serif;">b. electron......negative <span style="font-family: Arial,Helvetica,sans-serif;">c. neutron....negative <span style="font-family: Arial,Helvetica,sans-serif;">d. proton....neutral <span style="font-family: Arial,Helvetica,sans-serif;">e. electron.....neutral

5. Isotopes of an element differ intheir number of: a. electrons b. bonds formed by the atom c. protons d. neutrons e. nuclei

6. When hydrogen atoms lose one electron to become an ion, their net electrical charge is a. +1 b. -1 c. reamins neutral d. impossible to know from just this information provided

<span style="font-family: Arial,Helvetica,sans-serif;">7. A solution at pH of 4 contains the contentration of Hydrogen ions as the same amount of a solution with a pH of 2. <span style="color: #800080; font-family: Arial,Helvetica,sans-serif;">a. 2 times more <span style="font-family: Arial,Helvetica,sans-serif;">b. 2 times less <span style="font-family: Arial,Helvetica,sans-serif;">c. 20 times more <span style="font-family: Arial,Helvetica,sans-serif;">d. 20 times less <span style="font-family: Arial,Helvetica,sans-serif;">e. 100 times less

<span style="font-family: Arial,Helvetica,sans-serif;">8. This property of water makes it possible for columns of liquid water to rise from roots to leaves inside narrow pipelines of vascular tissues inside a plant. <span style="color: #800080; font-family: Arial,Helvetica,sans-serif;">a. cohesion <span style="font-family: Arial,Helvetica,sans-serif;">b. temperature <span style="font-family: Arial,Helvetica,sans-serif;">c. water sickness <span style="font-family: Arial,Helvetica,sans-serif;">d. surface tension <span style="font-family: Arial,Helvetica,sans-serif;">e. none of the above

<span style="font-family: Arial,Helvetica,sans-serif;">9. Bonds that form when atoms transfer one or more electrons are called bonds. <span style="font-family: Arial,Helvetica,sans-serif;">a. ionic <span style="font-family: Arial,Helvetica,sans-serif;">b. polar covalent <span style="font-family: Arial,Helvetica,sans-serif;">c. hydrogen <span style="color: #800080; font-family: Arial,Helvetica,sans-serif;">d. non-polar covalent

The rest of these questions are not in our workbook. <span style="font-family: Arial,Helvetica,sans-serif;">10. Within water molecules, the hydrogen atoms are bonded to the oxygen atom by <span style="font-family: Arial,Helvetica,sans-serif;">bonds, whereas the hydrogen atoms form _ bonds with <span style="font-family: Arial,Helvetica,sans-serif;">neighboring water molecules. <span style="font-family: Arial,Helvetica,sans-serif;">a. hydrogen…..ionic <span style="font-family: Arial,Helvetica,sans-serif;">b. ionic……hydrogen <span style="font-family: Arial,Helvetica,sans-serif;">c. polar covalent…….ionic <span style="font-family: Arial,Helvetica,sans-serif;">d. polar covalent……hydrogen <span style="font-family: Arial,Helvetica,sans-serif;">e. hydrogen…….polar covalent

<span style="font-family: Arial,Helvetica,sans-serif;">11. A solvent is <span style="font-family: Arial,Helvetica,sans-serif;">a. the dissolving agent of a solution <span style="font-family: Arial,Helvetica,sans-serif;">b. generally the liquid portion of a solution <span style="font-family: Arial,Helvetica,sans-serif;">c. usually water in living organisms <span style="font-family: Arial,Helvetica,sans-serif;">d. generally the portion of a solution found in smaller amount <span style="font-family: Arial,Helvetica,sans-serif;">e. A, B and C are all correct

<span style="font-family: Arial,Helvetica,sans-serif;">12. If a sample has a mass of 0.08 grams, what is this mass measured in milligrams? <span style="font-family: Arial,Helvetica,sans-serif;">a. 0.00008 <span style="font-family: Arial,Helvetica,sans-serif;">b. 0.008 <span style="font-family: Arial,Helvetica,sans-serif;">c. 0.08 <span style="font-family: Arial,Helvetica,sans-serif;">d. 8.0