Chapter 2: The Chemical Context of Life & Chapter 3: Water and Fitness of the Environment

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What is the mass number of an ion with 105 electrons, 159 neutrons, and a +1 charge?

265

The innermost electron shell of an atom can hold up to _____ electrons.

2

Which of these relationships is true of an uncharged atom?

The number of protons is equal to the number of electrons.

What determines the types of chemical reactions that an atom participates in?

the number of electrons in the outermost electron shell

What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?

6

Which of these refers to atoms with the same atomic number but different atomic masses?

These atoms are isotopes.

Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have?

10

An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have?

5

A(n) _____ refers to two or more atoms held together by covalent bonds.

molecule

What name is given to the bond between water molecules?

hydrogen

Atoms with the same number of protons but with different electrical charges _____.

are different ions

In salt, what is the nature of the bond between sodium and chlorine?

ionic

An ionic bond involves _____.

an attraction between ions of opposite charge

A covalent chemical bond is one in which

outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms.

A substance that cannot be broken down into other substances by ordinary chemical procedures is a(n) _____. (Concept 2.1)

element

Which of the following is a trace element required by most living organisms? (Concept 2.1)

magnesium

Which of the following subatomic particles always has a positive charge? (Concept 2.2)

proton

Changing the number of _____ would change an atom into an atom of a different element. (Concept 2.2)

protons in an atom

The atoms of different phosphorus isotopes _____. (Concept 2.2)

have different numbers of neutrons

How an atom chemically behaves when it comes into contact with other atoms is determined by its _____. (Concept 2.2)

electron configuration

Which of the following holds atoms together in a biological molecule? (Concept 2.3)
Hydrogen bonding.
Nonpolar covalent bonding.
Polar covalent bonding
Van der Waals interactions
All of the above.

All of the above

An ionic bond is formed when _____. (Concept 2.3)

one atom transfers an electron to another atom

Hydrogen bonding is most often seen _____. (Concept 2.3)

when hydrogen is covalently bonded to an electronegative atom

Chemical equilibrium is reached when _______ (Concept 2.4)

The forward and reverse reactions occur at the same rate so that the concentrations of reactants and products remain the same.

Each water molecule is joined to _____ other water molecules by ____ bonds.

four ... hydrogen

The unequal sharing of electrons within a water molecule makes the water molecule _____.

polar

The tendency of an atom to pull electrons toward itself is referred to as its _____.

electronegativity

Why isn't this insect drowning?

Surface tension

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

polar covalent bonds

In a neutral solution the concentration of _____.

hydrogen ions is equal to the concentration of hydroxide ions

Which of these is the correct equation for the dissociation of water?

H2O + H2O <==> H3O+ + OH-

What is the charge on a hydronium ion?

1+

What is the charge on a hydroxide ion?

1-

About _____ molecules in a glass of water are dissociated.

1 in 500,000,000

Which of the following ionizes completely in solution and is considered to be a strong acid?

HCl

Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as _____. (Concept 3.1)

hydrogen bonds

Many of water's emergent properties, such as its cohesion, its high specific heat, and its high heat of vaporization, result from the fact that water molecules _____. (Concept 3.2)

are electrically attracted to each other.

The amount of energy that must be absorbed or lost to raise or lower the temperature of 1 g of liquid water by °C _____. (Concept 3.2)

is 1 calorie

Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's _________. (Concept 3.2)

High Specific Heat

Sodas typically contain sugar, flavorings, coloring agents, and carbon dioxide dissolved in water. The best term to describe this mixture would be _____. (Concept 3.2)

an aqueous solution

If the molecular mass of a carbon atom is 12, the mass of a hydrogen atom is 1, and the mass of an oxygen atom is 16 daltons, how many molecules does one mole of sugar (C12H22O11) contain? (Concept 3.2)

6.02 x 1023

An acid is a substance that _____. (Concept 3.3)

increases the hydrogen ion concentration of an aqueous solution

A pH of 6 is how many times more acidic than a pH of 9? (Concept 3.3)

1,000

Select the statement that best describes a buffer. (Concept 3.3)

A buffer accepts hydrogen ions when they are in excess and donates hydrogen ions when they have been depleted.

Most acid precipitation results from the combination of ____ with water in the atmosphere, forming strong acids that fall with rain or snow. (Concept 3.3)

sulfur oxides and nitrogen oxides

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