Ionic And Covalent Bonding

Question 1

Covalent bonds are formed…

Answer 1

… between non metal atoms, which combine together by sharing electrons. Covalent compounds have no free electrons and no ions so they don’t conduct electricity.

Question 2

Properties of ionic compounds….

Answer 2

High melting and boiling points - ionic bonds are very strong and a lot of energy is needed to break them, so ionic compounds have high melting points and boiling points.

Conductive when liquid - ions are charged particles, but ionic compounds can only conduct electricity if their ions are free to move. So ionic compounds do not conduct electricity when they are solid, but they do conduct electricity when they are dissolved in water or when they are melted.

Question 3

Ionic bonds are…

Answer 3

… the electrostatic forces of attraction between oppositely-charged ions.

Question 4

Covalent compounds volatility…

Answer 4

Very volatile (Simple molecules)

Non-volatile (Giant molecules)

Question 5

Covalent bonds conducting electricity?

Answer 5

Cannot conduct electricity in any state (no free mobile ions)
Except graphite.

Question 6

Covalent bonds form between ____________atoms. Each bond consists of a shared ________ of electrons, and is very strong. Covalently bonded substances fall into two main types:

Answer 6

• non-metal-
• pair-

Simple molecules
Giant covalent structures

Question 7

Simple molecules ?

Answer 7

These contain only a few atoms held together by strong covalent bonds. An example is carbon dioxide (CO2), the molecules of which contain one atom of carbon bonded with two atoms of oxygen.

Question 8

Properties of simple molecular substances?

Answer 8

Low melting and boiling points - This is because the weak intermolecular forces break down easily.

Non-conductive - Substances with a simple molecular structure do not conduct electricity. This is because they do not have any free electrons or an overall electric charge.

Question 9

Giant covalent compounds?

Answer 9

Giant covalent structures contain a lot of non-metal atoms, each joined to adjacent atoms by covalent bonds.
The atoms are usually arranged into giant regular lattices - extremely strong structures because of the many bonds involved.

Question 10

Properties of giant covalent compounds

Answer 10

Very high melting points - Substances with giant covalent structures have very high melting points, because a lot of strong covalent bonds must be broken. Graphite, for example, has a melting point of more than 3,600ºC.

Variable conductivity - Diamond does not conduct electricity. Graphite contains free electrons, so it does conduct electricity. Silicon is semi-conductive - that is, midway between non-conductive and conductive.

Question 11

Graphite?

Answer 11

Graphite is a form of carbon in which the carbon atoms form layers. These layers can slide over each other, so graphite is much softer than diamond. It is used in pencils, and as a lubricant. Each carbon atom in a layer is joined to only three other carbon atoms. Graphite conducts electricity.

Question 12

Diamond?

Answer 12

Diamond is a form of carbon in which each carbon atom is joined to four other carbon atoms, forming a giant covalent structure. As a result, diamond is very hard and has a high melting point. It does not conduct electricity.

Because it’s hard it’s used in cutting and drilling tools.

Because is sparkles when cut, due to its regular structure, it is used for jewellery.