2 - Chemistry Covalent Bonding

What information does a molecular formula provide?

the number and kind of atoms present in a molecule

What is shown by the structural formula of a molecule or polyatomic ion?

the arrangement of bonded atoms

How do atoms achieve noble-gas electron configurations in single covalent bonds?

Two atoms share two electrons

Why do atoms share electrons in covalent bonds?

to attain a noble-gas electron configuration

Which of the following elements can form diatomic molecules held together by triple covalent bonds?

-carbon

-nitrogren

-oxygen

-fluorine

nitrogen

Which elements can form diatomic molecules joined by a single covalent bond?

hydrogen and the halogens only

What is the representative unit in a molecular compound?

a molecule

Which of the following diatomic molecules is joined by a double covalent bond?

-O2

-Cl2

-N2

-He2

O2

Which molecule has a single covalent bond?

-CO2

-Cl2

-CO

-N2

Cl2

Once formed, how are coordinate covalent bonds different from other covalent bonds?

there is no difference

When H+ forms a bond with H2O to form the hydronium ion H3O+, this bond is called a coordinate covalent bond because

both bonding electrons come from the oxygen atom

Which of the following bonds is the least reactive?

-C—C

-H—H

-O—H

-H—Cl

C—C

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?

0

In which of the following compounds is the octet expanded to include 12 electrons?

-H2S

-PCI3

-PCI5

-SF6

SF6

Which of the following bond types is normally the weakest?

-sigma bond formed by the overlap of two s orbitals

-sigma bond formed by the overlap of two p orbitals

-sigma bond formed by the overlap of one s and one p orbital

-pi bond formed by the overlap of two p orbitals

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?

pairs of valence electrons

The shape of the methane molecule (CH4) is

tetrahedral

What causes water molecules to have a bent shape, according to VSEPR theory?

repulsive forces between unshared pairs of electrons

Which of the following theories provides information concerning both molecular shape and molecular bonding?

-molecular orbital theory

-VSEPR theory

-orbital hybridization theory

-Bohr atomic theory

molecular orbital theory

Experimental evidence suggests that the H—C—H bond angles in ethene, C2H4, are

120 degrees

What type of hybrid orbital exists in the methane molecule?

sp³

What is the shape of a molecule with a triple bond?

linear

Which of the following atoms acquires the most negative charge in a covalent bond with hydrogen?

-C

-Na

-O

-S

O

Which of the following covalent bonds is the most polar?

-H—F

-H—C

-H—H

-H—N

H—F

When placed between oppositely charged metal plates, the region of a water molecule attracted to the negative plate is the

hydrogen region of the molecule

What is thought to cause the dispersion forces?

motion of electrons

Which of the forces of molecular attraction is the weakest?

dispersion forces

What causes dipole interactions?

attraction between polar molecules

What are the weakest attractions between molecules?

Van der Waals forces

What causes hydrogen bonding?

bonding of a covalently bonded hydrogen atom with an unshared electron pair

Why is hydrogen bonding only possible with hydrogen?

Hydrogen’s nucleus is electron deficient when it bonds with a highly electronegative atom.

Which type of solid has the highest melting point?

network solid

What is required in order to melt a network solid?

breaking covalent bonds

What is the total number of covalent bonds normally associated with a single carbon atom in a compound?

4

How many electrons are shared in a single covalent bond?

2

How many unshared pairs of electrons does the nitrogen atom in ammonia, NH3, possess?

1

How many electrons does carbon need to gain in order to obtain a noble-gas electron configuration?

4

How many covalent bonds are in a covalently bonded molecule containing 1 phosphorus atom and 3 chlorine atoms?

3

How many unshared pairs of electrons are in a molecule of hydrogen iodide?

3

What is the bond angle in a water molecule (in degrees)?

104.5 degrees

Which of the forces of molecular attraction is the weakest?

dispersion

Is the molecule pictured polar, nonpolar, partial, or neither?

nonpolar

Is the molecule pictured polar, nonpolar, partial, or neither?

polar

What are the seven elements found in nature as diatomic molecules?

Br2I2N2Cl2H2O2F2

What molecular shape is this molecule?

linear

What molecular shape is this molecule?

trigonal planar

What molecular shape is this molecule?

tetrahedral

What molecular shape is this molecule?

trigonal bipyramidal

What molecular shape is this molecule?

octahedral

What does VSEPR theory stand for

valence shell electron pair repulsion theory

Define a single covalent bond

only one pair of electrons is shared

Define a double covalent bond

two pairs of electrons are shared

Define a triple covalent pair

three pairs of electrons are shared

Define a coordinate covalent bond

When one atom shares more electrons than the other

What does lowercase delta signify in a covalent bond

That the atoms in the covalent bond acquire only partial charges, less than 1+ or 1-

The polar nature of a covalent bond may be represent by what in a diagram?

An arrow pointing to the more electronegative atom

How polar is a covalent bond with an electronegativity difference between 0 and 0.4 between atoms?

Non polar

How polar is a covalent bond with an electronegativity difference between 0.4 and 1 between atoms?

Moderately polar

How polar is a covalent bond with an electronegativity difference between 1 and 2 between atoms?

Very polar

How polar is a covalent bond with an electronegativity difference more than or equal to 2 between atoms?

Ionic