Chapter 2

Polar attractions are ... (a) forces between atoms with partial charges. (b) weaker than covalent bonds. (c) important because they are numerous. (a) and (b) are true. (c) is false. (a), (b), and (c) are correct.

(a), (b), and (c) are correct.

This atom can form up to _____ single covalent bond(s). 0 4 3 2 1

4

What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms? 2 4 3 6 8

6

A positive ion with two units of charge has 10 neutrons and 8 protons. The ion also has ... 12 electrons. 6 electrons. 10 electrons. 8 electrons. 16 electrons.

6 electrons.

What happens when two atoms form a chemical bond? Two atoms fuse together to form a chemical bond. A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells. A chemical bond forms when two atoms transfer or share protons to achieve a stable nucleus.

A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells.

Which statement is part of the explanation for water's high cohesion? (a) Oxygen has four valence orbitals. (b) Oxygen is much more electronegative than hydrogen. (c) Water can hydrogen-bond with other kinds of molecules. All of the above. Both (a) and (b).

Both (a) and (b).

What is the difference between covalent bonds and ionic bonds? Covalent bonds are formed between atoms to form molecules; ionic bonds are formed between atoms to form compounds. Covalent bonds involve the sharing of pairs of electrons between atoms; ionic bonds involve the sharing of single electrons between atoms. Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between atoms. Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between atoms. Covalent bonds involve the transfer of electrons between atoms; ionic bonds involve the sharing of electrons between atoms.

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

Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)? The nitrogen atom has a full positive charge; each hydrogen atom has a full positive charge. There are covalent bonds between the hydrogen atoms and polar bonds between each hydrogen atom and the nitrogen atom. Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge. The nitrogen atom has a partial positive charge; each hydrogen atom has a partial negative charge. Each hydrogen atom has a partial negative charge; the nitrogen atom has a full positive charge.

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

If you want a molecule that is highly polar, look for one that contains: H-N S-H C-S O-N C-H

H-N

Which of the following would be regarded as compounds? O2 and CH4 H2O and O2 H2O, O2, and CH4 CH4 and O2, but not H2O H2O and CH4, but not O2

H2O and CH4, but not O2

Why does ice float in liquid water? The crystalline lattice of ice causes it to be denser than liquid water. Ice always has air bubbles that keep it afloat. The ionic bonds between the molecules in ice prevent the ice from sinking. Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water. The high surface tension of liquid water keeps the ice on top.

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

Which answer correctly ranks the atoms in terms of decreasing electronegativity (the highest electronegativity first)? C, H, O, N O, N, H, C O, N, C, H N, O, H, C N, O, C, H

O, N, C, H

Use your knowledge of electronegativity to pick out the most polar bond in the list below. O-N O-C C-H N-H O-H

O-H

Which answer helps to explain how many hydrogen bonds a water molecule can form? Oxygen's valence shell has four orbitals. The oxygen atom has six protons. Water can ionize, making hydronium and hydroxide ions. Oxygen makes two covalent bonds. The angle between H-O bonds in water is 180.

Oxygen's valence shell has four orbitals.

Why isn't this insect drowning? The insect is flying just above the water surface. The insect is very light. Surface tension. The insect is swimming. It is difficult to change the temperature of water.

Surface tension.

True or false: Ions may form by transferring an atomic nucleus (with or without electrons) to another molecule. True False

True

Dr. Haxton says the O-O bond is polar and the C-C bond is nonpolar. A good student would say ... Wrong again, Ralph. Both bonds are nonpolar. No, both bonds are highly polar. Yes. O attracts electrons more strongly than C. Right! O is electronegative, so O2 is polar. No way. C is more electronegative than O.

Wrong again, Ralph. Both bonds are nonpolar.

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? a hydrogen bond a covalent bond an ionic bond a van der Waals interaction a hydrophilic bond

a hydrogen bond

What results from an unequal sharing of electrons between atoms? a polar covalent bond a hydrophobic interaction radioactive decay an ionic bond a nonpolar covalent bond

a polar covalent bond

An ionic bond involves _____. the unequal sharing of an electron pair water avoidance no atoms other than sodium and chlorine an attraction between ions of opposite charge the sharing of a single pair of electrons

an attraction between ions of opposite charge

Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that the atom would become a positively charged ion, or cation, and become a radioactive isotope. the atom may become a radioactive isotope. the atom would become a negatively charged ion, or anion. an electron may move to an electron shell farther away from the nucleus. an electron may move to an electron shell closer to the nucleus.

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

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 _____. are very small are attracted to each other by partial negative and positive charges on the oxygen and hydrogen atoms, respectively tend to repel each other are extremely large are in constant motion

are attracted to each other by partial negative and positive charges on the oxygen and hydrogen atoms, respectively

Atoms with the same number of protons but with different electrical charges _____. are different ions have different atomic numbers are different isotopes have different numbers of neutrons have different atomic masses

are different ions

Dr. Haxton told his class that a water molecule can make 4 hydrogen bonds, all of them in the same plane as the three atoms. What would a good student reply? (a) Wrong! Each atom makes one hydrogen bond, for a total of 3. (b) Right! Hydrogen bonds form at both ends of each covalent bond. (c) Wrong! Two hydrogen bonds are not in the plane of the atoms. None of the above. The student would say both (a) and (c).

c) Wrong! Two hydrogen bonds are not in the plane of the atoms.

Hydrogen bonds ... share electrons between the two bonded atoms. are covalent bonds. can form between H and N. occur within a water molecule. All of the above.

can form between H and N.

About 25 of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96% of living matter? carbon, oxygen, phosphorus, hydrogen carbon, hydrogen, nitrogen, oxygen carbon, sodium, hydrogen, nitrogen oxygen, hydrogen, calcium, nitrogen carbon, oxygen, nitrogen, calcium

carbon, hydrogen, nitrogen, oxygen

Water molecules are able to form hydrogen bonds with any compound that is not soluble in water. compounds that have polar covalent bonds. oxygen gas (O2) molecules. oils. chloride ions.

compounds that have polar covalent bonds.

What type of bond is joining the two hydrogen atoms? hydrophilic ionic hydrogen covalent hydrophobic

covalent

Which bond or interaction would be difficult to disrupt when compounds are put into water? hydrogen bond van der Waals interaction covalent bond ionic bond either covalent bond or ionic bond

covalent bond

A(n) _____ bond joins these two oxygen atoms. single covalent quadruple covalent ionic hydrogen double covalent

double covalent

A phrase that applies to covalent bonding and not other kinds of bonds is ... charge attraction. paired electrons. electron-sharing. great strength. All of the above.

electron-sharing.

The tendency of an atom to pull electrons toward itself is referred to as its _____. ionic potential covalency polarity electronegativity tonicity

electronegativity

Van der Waals interactions result when hybrid orbitals overlap. two polar covalent bonds react. electrons are not symmetrically distributed in a molecule. a hydrogen atom loses an electron. molecules held by ionic bonds react with water.

electrons are not symmetrically distributed in a molecule.

A substance that cannot be broken down into other substances by ordinary chemical procedures is a(n) _____. compound element molecule proton isotope

element

Each water molecule is joined to _____ other water molecules by ____ bonds. four ... hydrogen three ... ionic four ... polar covalent two ... polar covalent two ... hydrogen

four ... hydrogen

The atoms of different phosphorus isotopes _____. have different numbers of electrons have different atomic numbers react differently with other atoms have different numbers of protons have different numbers of neutrons

have different numbers of neutrons

Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's _____. cohesion buffering activity ability to form colloids high specific heat lower density in the solid phase

high specific heat

The brackets are indicating a(n) _____ bond. ionic hydrogen hydrophobic polar covalent single (nonpolar) covalent

hydrogen

What name is given to the bond between water molecules? hydrogen hydrophobic single (nonpolar) covalent polar covalent ionic

hydrogen

Which of the following explains most specifically the attraction of water molecules to one another? hydrogen bond ionic bond hydrophobic interaction polar covalent bond nonpolar covalent bond

hydrogen bond

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 _____. hydrogen bonds Van der Waals interactions ionic bonds polar covalent bonds nonpolar covalent bonds

hydrogen bonds

Despite its cohesion, water can flow because ... hydrogen bonds are too weak to affect movements. hydrogen bonds break and re-form rapidly. many water molecules have no hydrogen bonds. hydrogen ions can move between molecules. None of the above.

hydrogen bonds break and re-form rapidly.

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? phosphorus sodium nitrogen calcium iodine

iodine

In salt, what is the nature of the bond between sodium and chlorine? hydrophobic ionic nonpolar covalent polar covalent hydrogen

ionic

A(n) _____ refers to two or more atoms held together by covalent bonds. molecule shell community isotope ion

molecule

A carbon atom and a hydrogen atom form what type of bond in a molecule? ionic bond nonpolar covalent bond polar covalent bond hydrogen bond Van der Waals interaction

nonpolar covalent bond

When two atoms are equally electronegative, they will interact to form polar covalent bonds. ionic bonds. hydrogen bonds. nonpolar covalent bonds. van der Waals interactions.

nonpolar covalent bonds.

An ionic bond is formed when _____. both atoms are electrically neutral both atoms are nonpolar one atom transfers an electron to another atom both atoms are equally attractive to electrons atoms are subjected to radioactive isotopes

one atom transfers an electron to another atom

A covalent bond is likely to be polar when the two atoms sharing electrons are equally electronegative. one of the atoms has absorbed more energy than the other atom. the two atoms sharing electrons are different elements. oxygen is one of the two atoms sharing electrons. one of the atoms sharing electrons is much more electronegative than the other atom.

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

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. outer-shell electrons of one atom are transferred to fill the inner electron shell of another atom. an electron occupies a hybrid orbital located between the nuclei of two atoms. protons and neutrons are shared by two atoms so as to satisfy the requirements of both atoms. electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged.

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

The unequal sharing of electrons within a water molecule makes the water molecule _____. change easily from a liquid to gaseous form have a low surface tension polar hydrophobic ionic

polar

In this molecule, what type of bond is found between the oxygen and hydrogens? polar covalent nonpolar covalent hydrophobic hydrophilic ionic

polar covalent

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by polar covalent bonds. van der Waals interactions. hydrogen bonds. nonpolar covalent bonds. ionic bonds.

polar covalent bonds.

Which of the following subatomic particles always has a positive charge? neutron element atom electron proton

proton

Changing the number of _____ would change an atom into an atom of a different element. electrons circling the nucleus of an atom bonds formed by an atom protons in an atom particles in the nucleus of an atom neutrons in an atom

protons in an atom

Compared to covalent bonds, ionic bonds ... are more stable in water. have less bond energy. are more abundant in biological molelcules. are stronger. rely much less on electron-sharing.

rely much less on electron-sharing.

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? the release of heat by the formation of hydrogen bonds the absorption of heat by the breaking of hydrogen bonds water's high surface tension water's ability to dissolve molecules in the air water's change in density when it condenses

the absorption of heat by the breaking of hydrogen bonds

The partial negative charge in a molecule of water occurs because the oxygen atom acquires an additional electron. the oxygen atom has two pairs of electrons in its valence shell that are not neutralized by hydrogen atoms. the oxygen atom forms hybrid orbitals that distribute electrons unequally around the oxygen nucleus. the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atoms nucleus than around the hydrogen atoms nucleus. one of the hydrogen atoms donates an electron to the oxygen atom.

the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atoms nucleus than around the hydrogen atoms nucleus.

The type of bonding and the numbers of covalent bonds an atom can form with other atoms is determined by _____. the number of unpaired electrons in the valence shell the number of neutrons the size of the atom; smaller atoms are chemically more reactive the nucleus the number of protons

the number of unpaired electrons in the valence shell

One difference between carbon-12 (C) and carbon-14 (C) is that carbon-14 has two more protons than carbon-12. two more electrons than carbon-12. two more electrons and two more neutrons than carbon-12. two more neutrons than carbon-12. two more protons and two more neutrons than carbon-12.

two more neutrons than carbon-12.

Which property of water allows a water strider to walk on water? the formation of covalent bonds between water molecules water's high surface tension adhesion of water molecules to other kinds of molecules

water's high surface tension

Hydrogen bonding is most often seen _____. when the bonds within the molecule are nonpolar covalent bonds in molecules whose three-dimensional shape is tetrahedral when hydrogen is covalently bonded to an electronegative atom if the molecule consists of three or fewer atoms when multiple carbon atoms are present

when hydrogen is covalently bonded to an electronegative atom