New+Chapter+Two

Dmitri Mendeleev BIOL 160: General Biology
 * CHAPTER 2: Life’s Chemical Basis**

Definition Worksheet #2: Chapter 2 Define the following key terms. 1. Atom: Particals that are the building blocks of all substances. 2. Proton: Smaller particals of atoms which carry a posative charge (p+). 3. Neutron: Carries no charge. 4. Electron: Carries a negative charge (e-) 5. Atomic Number: Number of protons. Determins the element. 6. Atomic Mass: Total number of protons and neutrons in their nucleus. 7. Isotope: Same number of protons but different numbers of nuerons. 8. Ion: Different numbers of electrons and protons. 9. Cation 10. Anion 11. Molecule: Forms when two or more atoms of the same or different elements join in chemical bonds. 12. Chemical Bond: An attractive force that arises between two atoms when their electrons interact. 13. Ionic Bond: Is a strong mutual attraction of two oppositely charged ions. 14. Electronegativity: Measure of an atoms ability to pull electrons from other atoms. 15. Polar Covalent Bond: Do not share electrons evenly. 16. Non-polar Covale nt Bond: The atoms participating in the bond are sharing electrons evenly. 17. Hydrogen Bond: A weak attraction between a highly eledrogen atom taking part in a seperate polar covalent bond. 18. Solution 19. Solute: Dissolved substanses. 20. Solvent: A substance, usually a liquid, that can dissolve other substances. 21. Acid: Donate hydrogin ions as they dissolve in water. 22. Base: Accepts hydrogin ions. 23. Buffer: A set of chemicals often a weak acid or base and its salt that can keep the pH of a solution stable. 24. Salt

Characteristics of atoms
 * __CHAPTER 2__****: Basic Introduction to Chemistry**
 * Subatomic particle || Charge || Location || Mass ||
 * Proton || + || nucleus ||  ||
 * Neutron || N/A || nucleus ||  ||
 * Electron || - || around nucleus ||  ||

Recent discoveries have increased the number of naturally occurring elements from 92 to 94.

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).
 * Subatomic particle || Proton || Neutron || Electron ||
 * Proton || repulsion ||  ||   ||
 * Neutron ||  || neutral ||   ||
 * Electron || attraction ||  ||   ||

What is an element?


 * Atomic Number= # of protons ||

The periodic table of elements has elements placed in a repeating pattern based on their //chemical properties// and how they react with other
 * 1.** **Periodic Table**

mass of protons + neutrons || elements. (Appendix 4 in the back of the book shows a periodic table.)
 * Atomic Mass=


 * Principle || Definition || C || N || O || P || Fl || Na ||
 * Atomic Number || # of protons || 6 || 7 || 8 || 15 || 114 || 11 ||
 * Atomic Mass || # of protons & nuetrons || 12 || 14 || 16 || 30 || 289 || 23 ||
 * # of electrons ||  || 6 || 7 || 8 || 15 || 115 || 12 ||
 * # of protons ||  || 6 || 7 || 8 || 15 || 114 || 11 ||

2. What makes Carbon different than Hydrogen?

3. What is an isotope? Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei.

A. The element carbon has 3 main different isotopes: 12C has a mass of 12, due to __6__ protons and __6__ neutrons 13C has a mass of 13, due to __6__ protons and __7__ neutrons 14C has a mass of 14, due to __7__ protons and __7__ neutrons . 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). 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.
 * //Element// || //Symbol// || //Atomic Number// || //Atomic Mass// || //Number of Protons// || //Number of Neutrons// || //Number of Electrons// ||
 * Nitrogen-14 || N || 7 || 14 || 7 || 7 || 7 ||
 * Chlorine-35 || Cl || 17 || 35 || 17 || 18 || 17 ||
 * Oxygen-16 || O || 8 || 16 || 8 || 8 || 8 ||
 * Sodium-23 || Na || 11 || 11 || 11 || 0 || 11 ||
 * Sulfur-35 || S || 16 || 35 || 16 || 19 || 16 ||
 * Oxygen-17 || 0 || 8 || 17 || 8 || 9 || 8 ||

6. Complete the following matching activity.
 * A. || Radioisotope used to reveal the pathway or destination of a substance ||
 * B. || Subatomic particles with a negative charge ||
 * C. || Positively charged subatomic particles within the nucleus ||
 * D. || Subatomic particles within the nucleus carrying no charge ||
 * E. || Atoms of a given element that differ in the number of neutrons ||
 * F. || The number of protons in an atom ||
 * G. || Form of an element that emits radiation ||
 * H. || The number of protons and neutrons in the nucleus of one atom ||
 * I. || Pure substances, each consisting only of atoms with the same number of protons ||
 * J. || Smallest units of an element that retain the properties of a given element. Particles that are the building blocks of all substances. ||

atoms J protons C neutrons D electrons B atomic number F atomic mass H elements I isotope E radioisotopes G tracer A

7. Chemical Bonds Which subatomic particle participates in bonding between atoms? Electrons How do you figure out how many electrons there are in an atom? To find out how many electrons an atom has you must refer to the periodic table of elements. Find the element you are looking for then find that elements atomic number. The atomic number is the same as the number of protons that particular atom has. The atomic number also equals the number of electrons in a given atom of a given element.

B. Each horizontal row on the periodic table represents an energy level around the nucleus of an atom. __1.The first level is closest to the nucleus and can hold only 2___ __electrons due__ 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. __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).__ 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. __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.__

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**. 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) 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. The ability of an atom to “pull or take” electrons from another atom to become more stable is called ELECTRONEGATIVITY. 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? __P = 3__ __, Cl = 1__ __, O = 2__ __, N = 3__ __, S = 2__ __, C = 4__ __, Br = 1__
 * 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.

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? __Na = 1____, Al = 3__ __, Ca = 2__ __, K = 1__ __, C = 2__ __, Mg = 2__ __,__

G. Neutral atoms that “take” or “give away” electrons no longer remain neutral; they . There are two main types: become either negatively or positively charged particles called **ions**. There are two main types: 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. 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. (a force between two atoms that holds them together). **Chemical Bond** _ **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__. 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. 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. 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. 9. There are several important chemical bonds seen in biological molecules. A.IONIC BONDS: oppositely charged ions held close by attraction, electrons transferred (one loses, one gains) between atoms
 * Element Location || Giver? Taker? || What type of ion formed? || Positive or negatively charged ion? ||
 * Left side of per table || **Giver** || **Cation** || **Positive** ||
 * Right side of per. table || **Taker** || **Anion** || **Negative** ||

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: 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. 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. B. COVALENT BONDS: 1. What is a covalent bond?
 * A covalent bond is a chemical bond in which two atoms share a pair of electrons.**

2. Atoms with (similar, differing) electronegativities form covalent bonds.

Covalent Bond ||
 * Covalent Bond || # of electrons shared? || Example || Structural Formula || Strength ||
 * Single || 2 ||  || H-H || Strong ||
 * Double || 4 ||  || O=O || Stronger ||
 * Triple || 6 ||  || N_ _ _H || Stronger yet! ||
 * Between two identical atoms || 2 || H2 ||  || NONPOLAR Covalent Bond ||
 * Between two different atoms || 4 || H2O ||  || POLAR

More electrons in Oxygen, so that part of the molecule is more negatively charged; fewer electrons near Hydrogens, so that part of the molecule is less negatively charged ||
 * POLAR COVALENT BOND

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. 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:


 * Water (H2O) || # of e-s in outer shell || What combo would form an outer shell with 8 e-s? || Draw molecule ||
 * Hydrogen ||  ||   ||^   ||
 * Oxygen ||  ||   ||^   ||
 * Carbon Dioxide (CO2) || # of e-s in outer shell || What combo would form an outer shell with 8 e-s? || Draw molecule ||
 * Carbon ||  ||   ||^   ||
 * Oxygen ||  ||   ||^   ||

C. HYDROGEN BONDS: 1. What is a hydrogen bond? A weak attraction that has formed between a covalently bonded hydrogen atom and an electronegative atom in a different molecule or in a different part of the same molecule.

2. Are hydrogen bonds weak or strong attractions? weak

7. Water’s Life-Giving Properties This illustration shows how hydrogen bonds collectively stabilize water molecules. How does this affect the unique physical properties of water?

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.

b. Which part of a water molecule is slightly negative?

c. Which is partially positive?

d. How does this affect interaction with other nearby molecules of water? Or other types of molecules?

e.Why does water have such a high surface tension?

f. What is a solvent? **A solvent is a substance, usually a liquid, that can dissolve another substance**.

g. Why is water such a good solvent?

Positive ions attract the negative part of part of water (the atom), **Oxygen Atoms** atoms). h. Water’s Temperature-Stabilizing Effects: What is temperature? **Temperature is a measure of molecular motion. All molecules vibrate non-stop, and as they absorb heat they move faster. Temperature measures the energy produced in this molecular motion.**

Why is it hard to change the temperature of water? i. Water’s Cohesion: What is cohesion? **Cohesion is the tendency for molecules to stick together under tension; a property of liquid water. Cohesion allows molecules to resist seperating from one another.**

How does the cohesion of water molecules help transport water up inside of the tissues of plants? **The extensive hydrogen bonds in water molecules exert a continuous pull on other water molecules which allow columns of liquid water to rise from the roots to the leaves of plants.**

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). 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**//.// 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**//.// 1. Strong acids ionize completely releasing their hydrogen ions easily. One example is Hydrochloric acid (HCl) found in the stomach. __**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. 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 __to__. 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 __0 to **14**__. 1. Solutions with a value of “0” are very __**Acidic**___, meaning there is a high concentration of hydrogen ions in solution. 2. Solutions with a value of “14” are very __**Basic**__ (alkaline), 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. 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: A solution with a pH = 2 is 10 times more acidic than a solution of pH = 3. A solution with a pH = 5 is 100 times less acidic than a solution of pH = 3. A solution with a pH = 10 is 100 times more basic than a solution of pH = 8. A solution with a pH = 6 is 1000 times less basic than a solution of pH = 9. __D. **Salt**___ __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.__ _ 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. 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. Buffers can only work for so long, then the pH will shift rapidly.

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].

1. Tomato juice _ __2. Human blood **7.3 -7.5**__ **_** 3. Vinegar __**3 (A)_**__ 4. Pure Water __**7 (N)**__

5. Coffee __**5 (A)_**__ 6. Ammonia __**11 (B)**__ 7. Seawater __**8 (B)**__ 8. Typical rainwater __**5 (A)**__ 9. Oven/Drain cleaner __**13.5 (B)**__ 10. Antacid Pills __**9.5 (B)**__ 11. Urine __**5.5 (A)**__ __12. Gastric juice__ **_1 (A)**

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

Chapter review: Answer the following essay questions.

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?

b. If a hydrogen atom has one electron in its outer shellof electrons, how many covalent bonds is it likely to form with other atoms? Why?

c. What do you think the chemical formula for hydrogen sulfide would be? Hint: Look at the location of sulfur compared to oxygen on the periodic table.

15. In your own words, explain the main difference between a polar covalent bond and a nonpolar covalent bond.

16. If a water molecule is neutral (has no net charge), then why does it attract polar molecules and repel nonpolar ones.

17. Explain why sweating helps cool the body when it is overheated?

1. A substance that cannot be broken down into simpler substances by ordinary chemical means is known as a(n) a. molecule b. ion c. element d. compound e. isotope
 * //Sample Test Questions for chapter 2 and Lab #6://**

covalent bonds with other atoms. a. 2 b. 3 c. 4 d. 6 e. 8

3. A phosphorus atom has an atomic mass (mass number) of 31 and an atomic number of 15. How many PROTONS are there in a neutral phosphorus atom? a. 15 b. 16 c. 31 d. 46 e. none of the above __4. A__ __is a subatomic particle that carries a__ __charge.__ a. proton……negative b. electron…..negative c. neutron…..negative d. proton…..neutral e. electron……neutral

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

6. When hydrogen atoms lose one electon to become an ion, their net electrical charge is a. +1 b. -1 c. remains neutral d. impossible to know from just this information provided BIOL 160: Module 1 - 28 -

the concentration of Hydrogen ions 7. A solution at pH of 4 contains the concentration of Hydrogen ions as the same amount of a solution with a pH of 2. a. 2 times more b. 2 times less c. 20 times more d. 20 times less e. 100 times less

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. a. cohesion b. temperature c. water sickness d. surface tension e. none of the above bonds. a. ionic b. polar covalent c. hydrogen d. non-polar covalent

10. Within water molecules, the hydrogen atoms are bonded to the oxygen atom by __bonds, whereas the hydrogen atoms form__ _ __bonds with__ bonds, whereas the hydrogen atoms form _ bonds with neighboring water molecules. a. hydrogen…..ionic b. ionic……hydrogen c. polar covalent…….ionic d. polar covalent……hydrogen e. hydrogen…….polar covalent

11. A //solvent// is a. the dissolving agent of a solution b. generally the liquid portion of a solution c. usually water in living organisms d. generally the portion of a solution found in smaller amount e. A, B and C are all correct

12. If a sample has a mass of 0.08 grams, what is this mass measured in milligrams? a. 0.00008 b. 0.008 c. 0.08 d. 8.0 e. 80