Topic 2 - bonding, structure and properties of matter

Question 1

Ions

Answer 1

Charged particles

When atoms lose or gain electrons to form ions they are just trying to get a full outer shell to be stable

When electrons are lost the become positive ions

When electrons are gained they become negative ions

The number of electrons gained or lost is the same as the charge on the ion

Question 2

Diagrams which show how ionic bonds are formed

Answer 2

Dot and cross diagram

Question 3

Ionic compounds structure

Answer 3

• giant ionic lattice

- very strong electrostatic forces of attraction between oppositely charged ions as they are closely packed

Question 4

Ionic compounds properties

Answer 4

• all have high mp and bp due to the many strong bonds between the ions. Takes lots of energy to overcome this attraction
• when they’re solid the ions are held in place, so the compounds cant conduct electricity
• when ionic compounds melt, the ions are free to move and they’ll carry electric current
• dissolve easily in water. The ions separate and are all free to move in the solution so they’ll carry an electric current

Question 5

Ionic bonding is between

Answer 5

A non metal and a metal

Question 6

Covalent bonding is between

Answer 6

Two non metals

Question 7

Why covalent bonds are very strong

Answer 7

The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces

Question 8

Different ways of drawing covalent bonds

Answer 8

Dot and cross diagrams

Displayed formula

Question 9

Polymers

Answer 9

Lots of small units are linked together to form a long molecule that has repeating sections.

All atoms ina polymer are joined by strong covalent bonds

Question 10

Intermolecular forces of polymers

Answer 10

Larger than between simple covalent molecules, so more energy is needed to break them.

Still weaker than ionic or covalent, so generally have lower boiling points than ionic of giant molecular compounds

Question 11

Giant covalent structures

Answer 11

All atoms are bonded to each other by strong covalent bonds

Have very high melting and boiling points as lots of energy is needed to break the covalent bonds between the atoms

Don’t contain charged particles, so don’t conduct electricity

Question 12

Diamond

Answer 12

Giant covalent structure

Made up of carbon atoms that each form four covalent bonds-making diamond very hard

Strong covalent bonds take a lot of energy to break giving it a very high mp

Doesn’t conduct electricity as it has no free electrons or ions

Question 13

Graphite

Answer 13

Each carbon atom only forms three covalent bonds creating sheets of carbon atoms arranged in hexagons

Aren’t any covalent bonds between the layers - they’re only held together weakly so they’re free to move over each other - making it soft and slippery (ideal for a lubricant)

Has a high mp- covalent bonds in they layers need lots of energy to break

Only 3/4 of carbons outer electrons are used in bonds, so each carbon atom has one delocalised electron- so graphite conducts electricity and heat

Question 14

Graphene

Answer 14

A sheet of carbon atoms joined together in hexagons

Sheet is one atom thick making it a 2D compound

Network of covalent bonds makes it very strong

It is very light and can be added to composite materials to improve their strength without adding much weight

Contains delocalised electrons so can conduct electricity through the whole structure- potential to be used in electronics

Question 15

Fullerenes

Answer 15

Molecules of carbon shaped like closed tubes or hollow balls

Mainly made up of carbon atoms in hexagons

Can be used to ‘cage’ other molecules. The structure forms around another atom or molecule which is then trapped inside which could help to deliver a drug into the body

Huge surface area - could help make great industrial catalysts

Make good lubricants

Question 16

Metallic bonding is between

Answer 16

Two metals

Question 17

Why metallic bonding is very strong

Answer 17

Strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons hold the atoms together in a regular structure

Question 18

Why most metals are solid at room temperature

Answer 18

The electrostatic forces between the metal atoms and the delocalised sea of electrons are very strong, so need lots of energy to be broken - giving most compounds with metallic bonding high mp and bp

Question 19

Why metals are good conductors

Answer 19

The delocalised electrons carry electrical current and thermal energy through the whole structure so metals are good conductors of heat and electricity

Question 20

Why metals are malleable

Answer 20

The layers of atoms in a metal can slide over each other easily

Question 21

Why alloys are harder than pure metals

Answer 21

Different elements have different sized atoms which means the layers cant slide over each other as easily unlike pure metals

Question 22

Solids

Answer 22

1) strong forces of attraction between particles, which holds them close together in fixed positions to form a very regular lattice arrangement
2) particles don’t move from their positions,so all solids keep a definite shape and volume and don’t flow like liquids
3) particles vibrate about their positions - the hotter the solid is the more it vibrates (causing it to expand slightly)

Question 23

Liquids

Answer 23

1) weak force of attraction between the particles
2) they’re randomly arranged and free to move past each other but they tend to stick closely together
3) have a definite volume but don’t keep a definite shape and will flow to fill the bottom of a container
4) particles constantly move with random motion
5) hotter the liquid gets, the faster they move, causing liquids to expand slightly when heated

Question 24

Gases

Answer 24

1) Very weak forces of attraction between particles
2) free to move and are far apart and travel in straight lines
3) don’t keep a definite volume or shape and will always fill any container
4) particles move constantly with random motion - the hotter the gas gets the faster they move
5) gases either expand when heated or their pressure increases

Question 25

Nano particles

Answer 25

Have large surface area:volume ratio - help to make catalysts

Some conduct electricity so can be used in tiny electric circuits