2.1 Structure and Bonding

Question 1

Are the melting points of giant covalent substances very high or very low?

Answer 1

Very high as it takes a lot of energy to break the strong covalent bonds in the lattice.

Question 2

Does diamond conduct electricity?

Answer 2

No, as it has no free electrons since each carbon atom forms 4 bonds.

Question 3

Whats the difference between ionic and covalent bonding?

Answer 3

Ionic bonding is the transfer of electrons wheras covalent is the sharing of electrons.

Question 4

Give three examples of giant molecular substances

Answer 4

Silicon dioxide ( sand), diamond, graphite

Question 5

Why does graphite conduct electricity?

Answer 5

Yes, because it has delocalised electrons between the layers of carbon atoms. Each carbon atom only forms 3 bonds.

Question 6

True or false? Graphite is softer than diamond.

Answer 6

True, this is because graphite has layers of carbon atoms that can slide over each other easily

Question 7

Which type of substances bond covalently?

Answer 7

Non-metals

Question 8

Give three examples of simple covalent molecules?

Answer 8

Water, carbon dioxide and methane

Question 9

What happens when a metal and non- metal ironically bond?

Answer 9

When positive and negative ions attract to each other and bind together

Question 10

What is each ion surrounded by?

Answer 10

Oppositely charged ions

Question 11

What are the ions held in place by?

Answer 11

Electrostatic attractions forming an ionic crystal lattice

Question 12

When do atoms turn into ions?

Answer 12

When they lose or gain an electron

Question 13

How do you show ionic bonding?

Answer 13

Dot and cross diagram

Question 14

What is the overall charge of an ionic compound

Answer 14

0

Question 15

What is the formula of sodium ion?

Answer 15

Na+

Question 16

What is formula of a chlorine ion?

Answer 16

Cl-

Question 17

Are the melting points of ionic substances very high or very low?

Answer 17

High

Question 18

What happens when a metal and non- metal ionically bond?

Answer 18

The metal transfers electrons to the non-metal and becomes positively charged. The non-metal becomes negatively charged.

Question 19

What are the typical properties of ionic substances?

Answer 19

They have high melting and boiling points and conduct electricity when molten or in aqueous solution.

Question 20

Why do ionic compounds have high melting and boiling points?

Answer 20

They have strong electrostatic attractions between oppositely charged ions. These take a lot of energy to overcome.

Question 21

Why do they not conduct electricity when solid?

Answer 21

The ions are not free to move.

Question 22

Why do simple covalent molecules have low melting and boiling points?

Answer 22

The forces of attraction between molecules (intermolecular forces) are weak so do not require much energy to overcome them.

Question 23

What is the common arrangement for giant covalent structures?

Answer 23

They are commonly arranged into giant regular lattices: extremely strong structures, their strength caused by the many bonds inside these structures.