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anything that takes up space and has mass
made up of elements


a substance that cannot be broken down to other substances by chemical reactions, ei, oxygen


a substance consisting of two or more elements in a fixed ratio, ei, water

Compound Characteristics

characteristics different from those of its elements


the 92 elements are essential to life

90% of living matter

Carbon, hydrogen, oxygen, and nitrogen

Trace Elements

those required by an organism in minute quantities


the smallest unit of matter that still retains the properties of an element


No Charge


Positive Charged


Negative Charged

Forms the atomic nucleus

Neutrons and Protons

Cloud around the nucleus


Neutron and Proton Mass

Almost identical and are measured in Daltons

Atomic Number

The number of protons in its nucleus

Mass Number

The sum of protons plus neutrons in the nucleus

Atomic Mass & The atom's total mass

Can be approximated by the mass number


Two atoms of an element that differ in number of neutrons

Chemical behavior of an atom

Determined by the distribution of electrons in electron shells


Three-dimensional space where an electron is found 90% of the time

Valence Electrons

Those in the outermost shell, or valence shell


Elements with a full valence shell

Chemical bonds

Interactions usually result in atoms staying close together, held by attractions

Atoms with incomplete valence shells

Share or transfer valence electrons with certain other atoms.


1) A localized group of organisms that belong to the same species is called a

The potential energy of chemical bonds.

2) Organisms interact with their environments, exchanging matter and energy. For example, plant chloroplasts convert the energy of sunlight into

Light energy

3) The main source of energy for producers in an ecosystem is


4) Which of the following types of cells utilize deoxyribonucleic acid (DNA) as their genetic material but do not have their DNA encased within a nuclear envelope?


5) To understand the chemical basis of inheritance, we must understand the molecular structure of DNA. This is an example of the application of which concept to the study of biology?

Positive Feedback

6) Once labor begins in childbirth, contractions increase in intensity and frequency until delivery. The increasing labor contractions of childbirth are an example of which type of regulation?

Negative Feedback

7) When the body's blood glucose level rises, the pancreas secretes insulin and, as a result, the blood glucose level declines. When the blood glucose level is low, the pancreas secretes glucagon and, as a result, the blood glucose level rises. Such regulation of the blood glucose level is the result of


8) Which branch of biology is concerned with the naming and classifying of organisms?


9) Prokaryotic and eukaryotic cells generally have which of the following features in common?

Bacteria and Archaea

10) Prokaryotes are classified as belonging to two different domains. What are the domains?

) Limit the burning of fossil fuels and regulate our loss of forested areas.

11) Global warming, as demonstrated by observations such as melting of glaciers, increasing CO2 levels, and increasing average ambient temperatures, has already had many effects on living organisms. Which of the following might best offer a solution to this problem?


12) A water sample from a hot thermal vent contained a single-celled organism that had a cell wall but lacked a nucleus. What is its most likely classification?

Domain Eukarya, Kingdom Fungi

13) A filamentous organism has been isolated from decomposing organic matter. This organism has a cell wall but no chloroplasts. How would you classify this organism?

Near universality of the genetic code

14) Which of these provides evidence of the common ancestry of all life?

It requires genetic variation, results in descent with modification, and involves differential reproductive success.

15) Which of the following is (are) true of natural selection?


55) All the organisms on your campus make up

Understand the behavior of entire biological systems.

58) Systems biology is mainly an attempt to

Carbon, hydrogen, nitrogen, oxygen

1) About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter?


2) Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?

Virtually all organisms require the same elements in the same quantities.

3) Which of the following statements is false?

Both the relative abundances of the elements and the emergent properties of the compounds made from these elements

4) What factors are most important in determining which elements are most common in living matter?

Each element has a unique number of protons in its nucleus.

5) Why is each element unique and different from other elements in chemical properties?

both the number of protons and the chemical properties of the element

6) Knowing just the atomic mass of an element allows inferences about which of the following?

They have the same number of electron shells.

7) In what way are elements in the same column of the periodic table the same?

16 daltons

8) Oxygen has an atomic number of 8 and a mass number of 16. Thus, what is the atomic mass of an oxygen atom?

The nitrogen atom has a mass number of 14 and an atomic mass of approximately 14 daltons.

9) The nucleus of a nitrogen atom contains 7 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen?

Molybdenum atoms can have between 50 and 58 neutrons.

10) Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers of 92, 94, 95, 96, 97, 98, and 100. Therefore, which of the following can be true?

Some carbon atoms in nature have more neutrons.

11) Carbon-12 is the most common isotope of carbon, and has an atomic mass of 12 daltons. A mole of carbon in naturally occurring coal, however, weighs slightly more than 12 grams. Why?

The element may have multiple stable isotopes, and the isotopic composition may vary from sample to sample.

13) The precise weight of a mole of some pure elements like silicon (Si) can vary slightly from the standard atomic mass, or even from sample to sample. Why?


15) An atom has 6 electrons in its outer shell. How many unpaired electrons does it have?


16) The atomic number of nitrogen is 7. Nitrogen-15 is heavier than nitrogen-14 because the atomic nucleus of nitrogen-15 contains how many neutrons?

An electron may move to an electron shell farther away from the nucleus.

17) Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that

It has 8 electrons in its outer electron shell and it is inert.

18) The atomic number of neon is 10. Therefore, which of the following is most correct about an atom of neon?

15 protons and 15 electrons.

19) From its atomic number of 15, it is possible to predict that the phosphorus atom has

Be both chemically inert and gaseous at room temperature

20) Atoms whose outer electron shells contain 8 electrons tend to

must have the same number of protons + neutrons.

22) Two atoms appear to have the same mass number. These atoms


23) Fluorine has an atomic number of 9 and a mass number of 19. How many electrons are needed to complete the valence shell of a fluorine atom?


24) What is the maximum number of electrons in a single 2 p orbital of an atom?

It would form ions with a +2 charge.

27) An atom with atomic number 12 would have what type of chemical behavior in bonding with other elements?

protons and neutrons are shared by two atoms so as to satisfy the requirements of both atoms.

29) A covalent chemical bond is one in which


30) If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which of the molecules below would be formed?


31) What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen?

Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.

32) Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)?

Nonpolar Covalent Bond

33) When two atoms are equally electronegative, they will interact to form

Polar Covalent Bond

34) What results from an unequal sharing of electrons between atoms?

one of the atoms sharing electrons is much more electronegative than the other atom.

35) A covalent bond is likely to be polar when


36) Which of the following molecules contains the most polar covalent bond?

Covalent bonds and ionic bonds occupy opposite ends of a continuous spectrum, from nearly equal to completely unequal sharing of electrons.

37) In comparing covalent bonds and ionic bonds, which of the following would you expect?

Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between atoms.

38) What is the difference between covalent bonds and ionic bonds?

NH4, with a charge of +1

39) In ammonium chloride salt (NH4Cl) the anion is a single chloride ion, Cl. What is the cation of NH4Cl?


40) The atomic number of chlorine is 17. The atomic number of magnesium is 12. What is the formula for magnesium chloride?


41) How many electron pairs are shared between carbon atoms in a molecule that has the formula C2H4?

Covalent Bond

42) Which bond or interaction would be difficult to disrupt when compounds are put into water?

Hydrogen Bond

43) Which of the following explains most specifically the attraction of water molecules to one another?

electrons are not symmetrically distributed in a molecule.

44) Van der Waals interactions result when

van der Waals interactions

45) What bonding or interaction is most likely to occur among a broad array of molecules of various types (polar, nonpolar, hydrophilic, hydrophobic)?

Covalent Bond

46) Which of the following is not considered to be a weak molecular interaction?

H2O and CH4, but not O2

47) Which of the following would be regarded as compounds?


48) What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms?

Forward and reverse reactions continue with no effect on the concentrations of the reactants and products.

50) Which of the following correctly describes chemical equilibrium?

The rate of the forward reaction is equal to the rate of the reverse reaction.

51) Which of the following correctly describes any reaction that has reached chemical equilibrium?

a test tube of living cells

52) Which of these systems is least likely to be at chemical equilibrium?


53) Refer to the figure above (first three rows of the periodic table). If life arose on a planet where carbon is absent, which element might fill the role of carbon?


61) In the figure above, how many electrons does nitrogen have in its valence shell?


62) In the figure above, how many unpaired electrons does phosphorus have in its valence shell?


63) How many neutrons are present in the nucleus of a phosphorus-32 (32P) atom (see the figure above)?


64) How many electrons does an atom of sulfur have in its valence shell (see the figure above)?


65) Based on electron configuration, which of these elements in the figure above would exhibit a chemical behavior most like that of oxygen?

will form hydrogen bonds with water molecules.

66) The illustration above shows a representation of formic acid. A formic acid molecule

The element is required in very small amounts.

76) In the term trace element, the modifier trace means that

one more neutron.

77) Compared with 31P, the radioactive isotope 32P has

the existence of unpaired electrons in the valence shell.

78) The reactivity of an atom arises from

The atom has more electrons than protons.

79) Which statement is true of all atoms that are anions?

The rates of the forward and reverse reactions are equal.

80) Which of the following statements correctly describes any chemical reaction that has reached equilibrium?


82) The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound:

Polar Covalent Bond

1) In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

Hydrogen Bond

2) The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?

The electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom

3) The partial negative charge in a molecule of water occurs because

Will not form hydrogen bonds with each other.

4) Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S

Compounds that have polar covalent bonds.

5) Water molecules are able to form hydrogen bonds with

Kinetic energy in the drink decreases.

7) Which of the following takes place as an ice cube cools a drink?

Absorption and release of heat when hydrogen bonds break and form.

10) Liquid water's high specific heat is mainly a consequence of the

Hydrogen Bonds

11) Which type of bond must be broken for water to vaporize?

The release of heat by the formation of hydrogen bonds

12) Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon?

The water molecules with the most heat energy evaporate more readily

13) Why does evaporation of water from a surface cause cooling of the surface?

Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water.

14) Why does ice float in liquid water?

Nonpolar substances that repel water molecules.

15) Hydrophobic substances such as vegetable oil are

180 grams of glucose and 6.02 × 1023 molecules of glucose.

16) One mole (mol) of glucose (molecular mass = 180 daltons) is

(90/180) × 6.02 × 1023

17) How many molecules of glucose (C6H12O6 molecular mass = 180 daltons) would be present in 90 grams of glucose?

Ionizes completely in an aqueous solution.

25) A strong acid like HCl


26) Which of the following ionizes completely in solution and is considered to be a strong base (alkali)?

It is a strong acid that ionizes completely in water.

27) A 0.01 M solution of a substance has a pH of 2. What can you conclude about this substance?

acidic: will give H+ to weak acids, but accept H+ from strong acids

28) A given solution contains 0.0001(10-4) moles of hydrogen ions [H+] per liter. Which of the following best describes this solution?

pH 2

30) What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10-12 M?

pH 11

31) What is the pH of a 1 millimolar NaOH solution?

Gastric juice at pH 2

32) Which of the following solutions would require the greatest amount of base to be added to bring the solution to neutral pH?

10-8 M

33) What is the hydrogen ion [H+] concentration of a solution of pH 8?

concentration of H+ has increased tenfold (10X) and the concentration of OH- has decreased to one-tenth (1/10) what they were at pH 9.

34) If the pH of a solution is decreased from 9 to 8, it means that the

concentration of OH- is 100 times greater than what it was at pH 5.

35) If the pH of a solution is increased from pH 5 to pH 7, it means that the

They maintain a relatively constant pH when either acids or bases are added to them.

38) Which of the following statements is true about buffer solutions?

both donating H+ to a solution when bases are added, and accepting H+ when acids are added.

39) Buffers are substances that help resist shifts in pH by

the concentration of H+ ions in the water equals the concentration of OH- ions in the water.

45) If a solution has a pH of 7, this means that

positively charged.

53) Based on your knowledge of the polarity of water molecules, the solute molecule depicted here is most likely


54) How many grams would be equal to 1 mol of the compound shown in the figure above?
(carbon = 12, oxygen = 16, hydrogen = 1)

the absorption of heat by the breaking of hydrogen bonds

63) Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature?

hydrogen bonds between water molecules.

64) The bonds that are broken when water vaporizes are


65) Which of the following is a hydrophobic material?

Number of Molecules

66) We can be sure that a mole of table sugar and a mole of vitamin C are equal in their

10-4 M

67) Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?

10-10 M

68) Measurements show that the pH of a particular lake is 4.0. What is the hydroxide ion concentration of the lake?


54) Which drawing in the figure above depicts the electron configuration of an element with chemical properties most similar to Helium (2He)?


55) Which drawing in the figure above depicts the electron configuration of an atom that can form covalent bonds with two hydrogen atoms?


56) Which drawing in the figure above depicts the electron configuration of an atom capable of forming three covalent bonds with other atoms?


57) Which drawing in the figure above is of the electron configuration of a sodium 11Na+ ion?


58) Which drawing in the figure above depicts the most electronegative atom?


59) Which drawing in the figure above depicts an atom with a valence of 3?


60) Which drawing in the figure above depicts an atom with a valence of 2?

will form hydrogen bonds with water molecules.

66) The illustration above shows a representation of formic acid. A formic acid molecule


1) The element present in all organic molecules is

The chemical versatility of carbon atoms.

2) The complexity and variety of organic molecules is due to

living organisms can be understood in terms of the same physical and chemical laws that can be used to explain all natural phenomena.

3) The experimental approach taken in current biological investigations presumes that

differences in the types and relative amounts of organic molecules synthesized by each organism.

4) Differences among organisms are caused by


10) How many electron pairs does carbon share in order to complete its valence shell?


11) A carbon atom is most likely to form what kind of bond(s) with other atoms?

The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

14) Why are hydrocarbons insoluble in water?

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