3. Covalent Bonding

Question 1

What is the nature of a covalent bond?

Answer 1

It is a bond formed when atoms share (pairs or multiple pairs of) electrons.

Question 2

How many electrons are shared in a single, double and triple covalent bond?

Answer 2

single - 2
double - 4
triple - 6

Question 3

Why do atoms stay close together in a covalent bond?

Answer 3

Both positive nuclei (in the bond) are attracted to the negative electrons shared between then;
due to electrostatic forces;
therefore they indirectly are attracted to each other.

Question 4

Oxygen forms a double covalent bond. How many electrons are shared in the covalent bond?

Answer 4

4

Question 5

What is the name a of particle where two atoms are bonded covalently?

Answer 5

diatomic (molecule)

Question 6

Order the strength of the covalent bond in hydrogen, oxygen and nitrogen. Why is it this order?

Answer 6

Nitrogen, oxygen, hydrogen.

Nitrogen has a triple bond, oxygen double and hydrogen single

Question 7

Atoms need to be the same element in a diatomic molecule. True or False?

Answer 7

False - atoms can be different as long as there are two of them.

Question 8

How many covalent bonds will the following elements make: hydrogen, sulfur, bromine, nitrogen, carbon?

Answer 8

hydrogen - 1  
sulfur - 2
bromine - 1
nitrogen - 3
carbon - 4

Question 9

What are the thermal properties of simple molecular covalent substances?

Answer 9

Very low or low melting and boiling points

Question 10

Why do simple molecular covalent substances have low melting and boiling points?

Answer 10

There are strong covalent bonds within the molecule;

There are weak intermolecular forces between molecules; Little energy is required to break the intermolecular forces.

Question 11

What increases the melting and boiling points of simple molecular substances

Answer 11

Increasing the relative molecular mass.

Question 12

What are the thermal properties of giant covalent substances?

Answer 12

Very high melting and boiling points.

Question 13

Why do giant covalent substances have high melting and boiling points?

Answer 13

There are strong covalent bonds between all of the atoms; requiring a lot of energy to break.

Question 14

What are electrical conductivity properties of covalent substances?

Answer 14

Most do not conduct electricity (with the exception of graphite and graphene.)

Question 15

What are the properties of diamond and why?

Answer 15

Hard, high melting point;

There are strong covalent bonds between all of the atoms; requiring a lot of energy to break.

Question 16

What are the properties of graphite and why?

Answer 16

soft, conducts electricity
There are strong covalent bonds between the atoms in the layers of graphite; there are weak intermolecular forces between the layers; delocalised electrons are free move in the channels between the layers of graphite.

Question 17

What are the properties of C60 fullerenes?

Answer 17

Hard, high melting point, used as lubricants;

There are strong covalent bonds between all of the atoms; requiring a lot of energy to break; they are spheres.

Question 18

What are the uses of fullerenes?

Answer 18

Electronics
lubricants
drug delivery
catalysts