Chemistry Chapter 9

In a covalent molecular compound, the attraction between molecules tends to be strong.

False

The central atom in a molecule is the one with the highest electron affinity.

False

The electrons in a coordinate a covalent bond are donated by both bonded atoms.

False

The number of bonding pairs in a molecule is equal to the number of electrons .

False

To find the total number of electrons available for bonding in a positive ion, you should add the ion charge to the total number of valence electrons of the atoms present.

False

When carbon and oxygen bond, the molecule contains ten pairs of bonding electrons.

False

Which element has the highest electronegativity? What is the numerical value? What are the name and group number of the chemical family that has the highest overall electronegativities?

Florine, 3.98, halogen, group 7A

Which element has the lowest electronegativity? What is the numerical value? What are the name and group number of the chemical family that has the lowest overall electronegativities?

Francium, 0.7, Alkali metals, group 1A

What general trend in electronegativity do you note going down a group? Across a period?

Going down it gets lower, going right it gets higher.

A nonpolar covalent bond is one in which

electrons are shared equally.

The VSEPR model is based on the idea that

shared and unshared electron pairs repel each other as much as possible.

When carbon combines three p orbitals and its one s orbital, the orbitals that result are called _.

sp3

Unequal sharing of electrons between two bonded atoms always indicates

a polar covalent bond.

What factor other than electronegativity determine whether a molecule as a whole is polar or not?

Its geometry.

A molecule of ammonia, NH3, is

polar because there is an electronegativity difference and the molecule is trigonal pyramidal.

What is the electronegativity difference that usually is the dividing line between covalent and ionic bonds?

1.7

Fewer than 8 electrons around an atom (O3, BF3, NO, SF6)

BF3

All electrons in an atom are available for bonding.

False

What is the meaning of the term electronegativity?

Indicates the relative ability of an element's atoms to attract electrons in a chemical bond.

Odd number of valence electrons (O3, BF3, NO, SF6)

NO

What correctly describes the compound carbon tetra chloride, CCl4?

Nonpolar overall, with polar covalent bonds.

More than one valid Lewis structure (O3, BF3, NO, SF6)

O3

What correctly describes the compound water H2O?

Polar overall, with polar covalent bonds.

More than 8 electrons around central atom (O3, BF3, NO, SF6)

SF6

The symbol delta is placed next to what?

The less electronegative atom in a polar covalent bond.

A structural formula shows the arrangement of the atoms in a molecule.

True

In molecules, hydrogen is always a terminal atom.

True

In the sulfate ion (SO4 2-), 32 electrons are available for bonding.

True

Ionic compounds are usually soluble in polar substances.

True

Nitrate is an example of an ion that forms resonance structures.

True

Resonance occurs when more than one valid Lewis structure can be written for a molecule.

True

The carbon dioxide molecule contains two double bonds.

True

How are the electronegativity values used to determine the type of bond that exists between two atoms?

You're going to take the difference.

An example of an element that commonly undergoes hybridization is _.

carbon

The VSEPR model is used mainly to

determine molecular shape.

The formation of new orbitals from a combination or rearrangement of valence electrons is called _.

hybridization

The orbitals that are produced through hybridization are _ to one another.

identical

The shape of a molecule that has two covalent single bonds and no lone pairs on the central atom is

linear.

When electronegativities of two bonded atoms differ greatly, the bond is

ionic.

Molecules containing only polar covalent bonds

may or may not be polar.

An example of a molecule that has sp3 is _.

methane

The shape of a molecule whose central atom has four pairs of bonding electrons is

tetrahedral.

The shape of a molecule that has three single covalent bonds and one lone pair on the central atom is

trigonal pyramidal.

The bond angle is the angle between

two terminal atoms and the central atom.