Chemistry: Chapter 8 Covalent Bonding

a depiction of the arrangement of atoms in molecules and polyatomic ions

a covalent bond in which only one pair of electrons is shared

a covalent bond in which two pairs of electrons are shared

a covalent bond in which the shared electron pair comes from only one of the atoms

a covalent bond between two atoms of significantly different electronegativities

a type of bond that is very important in determining the properties of water and of important biological molecules such as proteins and DNA

energy needed to break a single bond between two covalently bonded atoms

symmetrical bond along the axis between the two nuclei

molecular orbital that can be occupied by two electrons of a covalent bond

109.5

shapes adjust so valence-electron pairs are as far apart as possible

attraction between polar molecules

crystal in which all the atoms are covalently bonded to each other

What information does a molecular formula provide?
a. the number and kind of atoms that are bonded by the transfer of electrons
b. the simplest whole-number ratio of atoms that are bonded by the transfer of electrons
c. information about a molecule’s structure
d. the number and kind of atoms present in a molecule

What is shown by the structural formula of a molecule or polyatomic ion?
a. the arrangement of bonded atoms
b. the number of ionic bonds
c. the number of metallic bonds
d. the shapes of molecular orbitals

The molecular formula for the compound hydrogen cyanide is HCN. What information does the molecular formula provide about hydrogen cyanide?
a. The formula HCN indicates that a molecule of hydrogen cyanide contains one hydrogen atom, one carbon atom, and one nitrogen atom.
b. The formula HCN shows that hydrogen cyanide could contain 2 atoms of each element; hydrogen, carbon and nitrogen, as long as there is a one to one ratio.
c. The formula HCN shows that hydrogen cyanide has a single covalent bond between the hydrogen and carbon atoms and a triple covalent bond between the carbon and nitrogen atoms.
d. The formula HCN shows that hydrogen cyanide has a single ionic bond between the hydrogen and carbon atoms and a triple ionic bond between the carbon and nitrogen atoms.

How do atoms achieve noble-gas electron configurations in single covalent bonds?
a. One atom completely loses two electrons to the other atom in the bond.
b. Two atoms share two pairs of electrons.
c. Two atoms share two electrons.
d. Two atoms share one electron.

Why do atoms share electrons in covalent bonds?
a. to become ions and attract each other
b. to attain a noble-gas electron configuration
c. to become more polar
d. to increase their atomic numbers

Which of the following elements can form diatomic molecules held together by triple covalent bonds?
a. carbon
b. oxygen
c. fluorine
d. nitrogen

Which noble gas has the same electron configuration as the oxygen in a water molecule?
a. helium
b. neon
c. argon
d. xenon

Which elements can form diatomic molecules joined by a single covalent bond?
a. hydrogen only
b. halogens only
c. halogens and members of the oxygen group only
d. hydrogen and the halogens only

What is the representative unit in a molecular compound?
a. a molecule
b. an ion
c. a formula unit
d. shared electrons

Which of the following electron configurations gives the correct arrangement of the four valence electrons of the carbon atom in the molecule methane (CH )?
a. 2s² 2p²
b. 2s¹ 2p¹ 3s¹
c. 2s¹ 2p² 3s¹
d. 2s¹ 2p ³

Which of the following diatomic molecules is joined by a double covalent bond?
a. 0²
b. Cl²
c. N²
d. He²

Which molecule has a single covalent bond?
a. CO²
b. Cl²
c. CO²
d. N²

The chemical formula of an ionic compound shows
a. how many atoms of each element a molecule contains.
b. the lowest whole-number ratio between ions in the ionic compound.
c. which molecules the ionic compound contains.
d. how the atoms bond.

Once formed, how are coordinate covalent bonds different from other covalent bonds?
a. They are stronger.
b. They are more ionic in character.
c. They are weaker.
d. There is no difference.

When H forms a bond with H O to form the hydronium ion H O , this bond is called a coordinate covalent bond because
a. both bonding electrons come from the oxygen atom.
b. it forms an especially strong bond.
c. the electrons are equally shared.
d. the oxygen no longer has eight valence electrons.

Which of the following bonds is the least reactive?
a. C—C
b. H—H
c. O—H
d. H—Cl

How many valid electron dot formulas—having the same number of electron pairs for a molecule or ion—can be written when a resonance structure occurs?
a. 0
b. 1 only
c. 2 only
d. 2 or more

In which of the following compounds is the octet expanded to include 12 electrons?
a. H S
b. PCl
c. PCl
d. SF

A resonance structure, like the one above, represents
a. a difference in energy.
b. electron pairs resonating back and forth between the extremes of the two structures.
c. a difference in bond length, one shorter than the other.
d. a hybrid of the extremes represented by the resonance forms.

Molecular orbital theory is based upon which of the following models of the atom?
a. classical mechanical model
b. Bohr model
c. quantum mechanical model
d. Democritus’s model

A bond that is not symmetrical along the axis between two atomic nuclei is a(n) ____.
a. alpha bond
b. sigma bond
c. pi bond
d. beta bond

A pair of molecular orbitals is formed by the
a. splitting of a single atomic orbital.
b. reproduction of a single atomic orbital.
c. overlap of two atomic orbitals from the same atom.
d. overlap of two atomic orbitals from different atoms.

The side-by-side overlap of p orbitals produces what kind of bond?
a. alpha bond
b. beta bond
c. pi bond
d. sigma bond

Where are the electrons most probably located in a molecular bonding orbital?
a. anywhere in the orbital
b. between the two atomic nuclei
c. in stationary positions between the two atomic nuclei
d. in circular orbits around each nucleus

Sigma bonds are formed as a result of the overlapping of which type(s) of atomic orbital(s)?
a. s only
b. p only
c. d only
d. s and p

Which of the following bond types is normally the weakest?
a. sigma bond formed by the overlap of two s orbitals
b. sigma bond formed by the overlap of two p orbitals
c. sigma bond formed by the overlap of one s and one p orbital
d. pi bond formed by the overlap of two p orbitals

According to VSEPR theory, molecules adjust their shapes to keep which of the following as far apart as possible?
a. pairs of valence electrons
b. inner shell electrons
c. mobile electrons
d. the electrons closest to the nuclei

The shape of the methane molecule is ____.
a. tetrahedral
b. square
c. four-cornered
d. planar

What causes water molecules to have a bent shape, according to VSEPR theory?
a. repulsive forces between unshared pairs of electrons
b. interaction between the fixed orbitals of the unshared pairs of oxygen
c. ionic attraction and repulsion
d. the unusual location of the free electrons

Which of the following theories provides information concerning both molecular shape and molecular bonding?
a. molecular orbital theory
b. VSEPR theory
c. orbital hybridization theory
d. Bohr atomic theory

Experimental evidence suggests that the H—C—H bond angles in ethene, C H , are ____.
a. 90
b. 109.5
c. 120
d. 180

What type of hybrid orbital exists in the methane molecule?
a. sp
b. sp²
c. sp³
d. sp³ d²

What is the shape of a molecule with a triple bond?
a. tetrahedral
b. pyramidal
c. bent
d. linear

What type of hybridization occurs in the orbitals of a carbon atom participating in a triple bond with another carbon atom?
a. sp³
b. pd
c. sp
d. sp²

How many pi bonds are formed when sp hybridization occurs in ethene, C H ?
a. 0
b. 1
c. 2
d. 3

Which of the following atoms acquires the most negative charge in a covalent bond with hydrogen?
a. C
b. Na
c. O
d. S

A bond formed between a silicon atom and an oxygen atom is likely to be ____.
a. ionic
b. coordinate covalent
c. polar covalent
d. nonpolar covalent

Which of the following covalent bonds is the most polar?
a. H—F
b. H—C
c. H—H
d. H—N

When placed between oppositely charged metal plates, the region of a water molecule attracted to the negative plate is the ____.
a. hydrogen region of the molecule
b. geometric center of the molecule
c. H—O—H plane of the molecule
d. oxygen region of the molecule

What is thought to cause the dispersion forces?
a. attraction between ions
b. motion of electrons
c. sharing of electron pairs
d. differences in electronegativity

Which of the forces of molecular attraction is the weakest?
a. dipole interaction
b. dispersion
c. hydrogen bond
d. single covalent bond

What causes dipole interactions?
a. sharing of electron pairs
b. attraction between polar molecules
c. bonding of a covalently bonded hydrogen to an unshared electron pair
d. attraction between ions

What are the weakest attractions between molecules?
a. ionic forces
b. Van der Waals forces
c. covalent forces
d. hydrogen forces

What causes hydrogen bonding?
a. attraction between ions
b. motion of electrons
c. sharing of electron pairs
d. bonding of a covalently bonded hydrogen atom with an unshared electron pair

Why is hydrogen bonding only possible with hydrogen?
a. Hydrogen’s nucleus is electron deficient when it bonds with an electronegative atom.
b. Hydrogen is the only atom that is the same size as an oxygen atom.
c. Hydrogen is the most electronegative element.
d. Hydrogen tends to form covalent bonds.

Which type of solid has the highest melting point?
a. ionic solid
b. network solid
c. metal
d. nonmetallic solid

What is required in order to melt a network solid?
a. breaking Van der Waals bonds
b. breaking ionic bonds
c. breaking hydrogen bonds
d. breaking covalent bonds