Chemistry Topic 4

Question 1

What allows ionic bonds to form?

Answer 1

Elements having a large difference in electronegativity

Question 1

Define ionic bond

Answer 1

The electrostatic forces of attraction between oppositely-charged ions

Question 2

How are ionic compounds arranged?

Answer 2

A 3D crystalline structure called an ionic lattice

Question 3

What is a coordinate number?

Answer 3

The number of ions that surround a given ion in an ionic lattice

Question 4

What is lattice enthalpy and what does it depend upon?

Answer 4

Lattice enthalpy is the strength of the force between ions in an ionic compound, and it depends upon the size of the ion and the charge

Question 5

What is charge density?

Answer 5

The charge per unit volume of an ionic compound

Question 6

Why do ionic compounds tend to have high melting and boiling points?

Answer 6

Because the electrostatic forces of attraction between ions is very strong and requires high amounts of energy to break

Question 7

What two factors determine the melting point of an ionic compound?

Answer 7

Ionic radius and the charge on the ion

Question 8

As ionic radius increases, melting point _______

Answer 8

Decreases!

Question 9

As the charge on the ion increases, melting point ______

Answer 9

Increases!

Question 10

Do ionic compounds tend to have high or low volatility, and why?

Answer 10

Low voltality because they have strong electrostatic forces of attraction

This means they do not readily escape to the vapor phase

Question 11

What does electrical conductivity depend upon?

Answer 11

The fact that ions are able to carry a charge (freely moving charged particles)

Question 12

Are ionic compounds usually brittle?

Answer 12

Yes! This means the crystals typically shatter when force is applies

Question 13

What causes the crystal lattice to split when force is applied?

Answer 13

When force is applied, ions of the same charge get moved next to each other, so the repulsive forces exerted by the ions cause the lattice to split

Question 14

If the difference in electronegativity increases, then ionic character ________

Answer 14

Increases!

Question 15

What is bond length and what unit is it expressed in?

Answer 15

Bond length is the measure of the distance between two covalently bonded nuclei, and it is expressed in picometers (pm)

Question 16

What is bond strength and what unit is it expressed in?

Answer 16

Bond strength is a measure of the energy required to break a covalent bond, and it is expressed in KJ/mol

Question 17

Bond length and bond strength have what kind of relationship?

Answer 17

An inverse relationship

Question 18

As you go from single to double to triple bonds, bond length (increases/decreases), and bond strength (increases/decreases)

Answer 18

Decreases; increases

Question 19

Which bonds are stronger, shorter or longer bonds, and why?

Answer 19

Shorter bonds are stronger than weaker bonds because as bond length increases, the distance of the shared pair of electrons from the nucleus increases, which reduces the bond strength

Question 20

What two values classify covalent bonds?

Answer 20

Bond length and bond strength

Question 21

In a covalent bond, which side is always the slightly negative side?

Answer 21

The side with the atom that has a higher electronegativity because the electrons are being pulled in closer

Question 22

What elements can exceed the octet rule?

Answer 22

Elements that are in period 3 or higher because they have d sublevels to hold “extra” electrons

Question 23

When multiple atoms can exceed the octet rule, where should we place the extra lone pairs?

Answer 23

On the central atom

Question 24

What does VSEPR stand for?

Answer 24

Valence Shell Electron Pair Repulsion

Question 25

What is VSEPR

Not what it stands for, what it is

Answer 25

The shape of a molecule is due to repulsions between pairs of electrons outside the shell of the central atom

Question 26

Molecules take shape to ____ repulsions

Answer 26

Minimize!