Chapter 2

Question 1

Covalent bonds

Answer 1

may be single, double, or triple bonds and can vary in orientation and share one or more electron pairs

Question 2

What is the molecular formula and approximate atomic weight of the following biological molecule?
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH

Answer 2

C14H28O2; 228 Da

Question 3

Oxygen (O) has an atomic number of 8. What is the approximate atomic mass of an oxygen atom in daltons?

Answer 3

16

Question 4

Which defines a compound?

Answer 4

A pure substance with a fixed ratio of two or more elements that are combined through bonds

Question 5

Which particles determine how an atom interacts with other atoms?

Answer 5

Electrons

Question 6

A(n) _______ is an atom that has gained or lost one or more electrons. A(n) _______ bond is created by a(n) _______ attraction between two _______ atoms.

Answer 6

ion; ionic; electrical; charged

Question 7

When a chemical reaction occurs, changes in the form of _______ occur, which represents the capacity of the reaction to do _______.

Answer 7

energy; work

Question 8

A cation has the opposite charge from a(n)

Answer 8

anion.

Question 9

A helium atom contains

Answer 9

two negatively charged electrons.

Question 10

The term hydrophobic is the opposite of

Answer 10

hydrophilic

Question 11

Biological organisms are made of

Answer 11

atoms, elements, water, other molecules, and ions.

Question 12

If 1 calorie of energy is needed to raise 1 g of water by 1°C, what is the amount of energy needed to raise 15 g of water by 3°C?

Answer 12

45 calories

Question 13

Water has _______ nonbonding electrons pair(s) and _______ bonding electron pair(s).

Answer 13

2,2

Question 14

What is the significance of Avogadro’s number?

Answer 14

It is the number of molecules in a mole

Question 15

How many electrons occupy the 2s orbital in an oxygen atom?

Answer 15

2

Question 16

What is not an example of a chemical bond or interaction?

Answer 16

Electronegativity

Question 17

Which six elements provide most of the mass of biological organisms?

Answer 17

C, O, N, H, P, S

Question 18

What is the maximum number of electrons contained in a single p orbital?

Answer 18

2

Question 19

Van der Waals interactions are most similar to

Answer 19

weak nonpolar interactions

Question 20

In the periodic table, when elements are in the same vertical column, they share a similar

Answer 20

number of valence electrons

Question 21

Buffers demonstrate which important chemical principle?

Answer 21

The law of mass action

Question 22

Another term for atomic weight is

Answer 22

relative atomic mass

Question 23

The electronegativity of an atom is a relative measure of the

Answer 23

affinity an atom has for electrons and its ability to capture additional electrons.

Question 24

Why does sodium chloride (NaCl) dissolve in water?

Answer 24

Water is a polar solvent

Question 25

The equation C4H10 + 7 O2 → 4 CO2 + 6 H2O + energy is incorrect because

Answer 25

two hydrogen atoms are missing from the reactants

Question 26

P orbitals are not

Answer 26

found in all atoms with atomic number 2 and higher.

Question 27

A molecule's three-dimensional shape varies by _______ without changing the bond angles or its stability.

Answer 27

rotating atoms around a covalent bond

Question 28

The _______ in an aqueous solution is water.

Answer 28

solvent

Question 29

______ capacity is a term used to describe the ability of a solution to prevent large changes in pH with the addition of a base or acid.

Answer 29

Buffering

Question 30

An aqueous solution with a mixture of a _______ acid and its corresponding _______ is called a(n) _______.

Answer 30

weak; base; buffer

Question 31

In which column/group in the periodic table would you expect to find elements with five valence electrons?

Answer 31

The group that starts with N

Question 32

Which atom, sodium or chloride, is more electronegative? Which will "steal" an electron from the other?

Answer 32

chloride; chloride

Question 33

In the periodic table, why are hydrogen, lithium, and sodium in the same column?

Answer 33

They have the same number of unpaired electrons

Question 34

If carbon dioxide has a molecular weight of approximately 44, then 0.25 moles of carbon dioxide has

Answer 34

a molecular weight of 11

Question 35

Which orbitals would you expect to be occupied in a fluorine atom?

Answer 35

1s, 2s, 2px, 2py, 2pz

Question 36

H3C - CH3

Answer 36

Nonpolar

Question 37

_______ is the heaviest isotope of the element whose atomic number is 1.

Answer 37

Tritium

Question 38

Living organisms obey the same laws of _______ and _______ as everything else on our planet.

Answer 38

chemistry; physics

Question 39

The Bohr model of an atom does not emphasize

Answer 39

the relationship between s orbitals and p orbitals

Question 40

Why does a water molecule have a tetrahedral shape?

Answer 40

Because oxygen bonds to two hydrogen atoms and oxygen contains two sets of unpaired electrons

Question 41

H3C - OH

Answer 41

Polar

Question 42

A double covalent bond involves how many electrons?

Answer 42

4

Question 43

An orbital determines the _______ and _______ of its corresponding electron shell.

Answer 43

energy level; orientation and geometry

Question 44

What best explains how atoms change partners when propane combusts?

Answer 44

Oxygen breaks a bond with oxygen and forms a bond with carbon or hydrogen.

Question 45

Hydrogen bonds are most similar to

Answer 45

polar interactions.