Topic 2 - Bonding, Structure and Properties of Matter

Question 1

What is an ion?

Answer 1

Ions are charged particles - they can be single atoms e.g. Cl- or groups of atoms e.g. NO3-

Question 2

Why do ions gain/lose electrons ?

Answer 2

Ions gain or lose electrons in order to obtain a full valence shell like a noble gas (“stable electronic structure”). Atoms with a full valence shell are very stable

Question 3

What happens to metals when they form ions?

Answer 3

When metals form ions, they lose electrons from their valence shell to form positively charged ions

Question 4

What happens to non-metals when they form ions?

Answer 4

When non-metals form ions, they gain electrons in their valence shell to form negative ions

Question 5

What is ionic bonding?

Answer 5

When a metal and a non-metal react together, the metal atom loses electrons to form a positively charged ion and the non metal gains these electrons to form a negatively charged ion. The oppositely charged ions are strongly attracted to each other by electrostatic forces in a process known as ionic bonding

Question 6

What is the structure of an ionic compound?

Answer 6

Ionic compounds have a ‘giant lattice structure’

Question 7

Outline some of the main properties of ionic compounds

Answer 7

• They all have high melting points due to the many strong bonds between the ions. It takes a lot of energy to overcome this force of attraction
• When they are solid, the ions are held in place so the compounds cannot conduct electricity. In molten form however, the ions are free to move and are therefore free to carry electric current

Question 8

Can aqueous ionic compounds conduct electricity?

Answer 8

Some ionic compounds dissolve in water meaning that the ions in the water are all free to move and therefore can carry charge

Question 9

What type of bonding involves a shared pair of electrons?

Answer 9

Covalent bonding involves a shared pair of electrons

Question 10

Describe and explain the strength of covalent bonds

Answer 10

Covalent bonds are very strong as the charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces

Question 11

Where does covalent bonding occur mostly?

Answer 11

Covalent bonding occurs mostly in compounds of non-metals e.g. H2O and in non-metal elements e.g. Cl2

Question 12

How are the atoms in a polymer bonded together?

Answer 12

Atoms in a polymer are bonded together through strong, covalent bonds

Question 13

Describe the strength of inter-molecular forces between polymer molecules and simple covalent molecules

Answer 13

Inter-molecular forces between polymer molecules are larger than between simple covalent molecules - therefore more energy is needed to break them

Question 14

Can giant covalent structures conduct electricity?

Answer 14

Giant covalent structures do not contain charged particles so they don’t conduct electricity - even when molten. However, graphite is an exception to this

Question 15

Describe the boiling and melting points of giant covalent structures

Answer 15

Giant covalent structures have very high melting and boiling points as a lot of energy is needed to break the covalent bonds between the atoms

Question 16

Give three examples of giant covalent structures

Answer 16

• Diamond (carbon atoms only)
• Graphite (carbon atoms only)
• Silicon dioxide

Question 17

Can graphite conduct electricity? Why (not) ?

Answer 17

Each of the carbon atoms has one de-localised electron and is therefore able to carry charge and conduct electricity

Question 18

Describe and explain the physical properties of diamond (hardness)

Answer 18

Diamond has a giant covalent structure made up of carbon atoms that each form four covalent bonds. This means that diamond is very hard. This also means that diamond has a very high melting point

Question 19

Can diamond conduct electricity ? Why (not) ?

Answer 19

Diamond cannot conduct electricity because it has no free electrons or ions to carry charge

Question 20

Describe the shapes of fullerenes

Answer 20

Fullerenes have closed tube or spherical shapes

Question 21

What is an allotrope?

Answer 21

Allotropes are different structural forms of the same element in the same physical state