Bonding

Question 1

Ionic lattice

Answer 1

Billions of oppositely charged ionic compounds packed together with strong electrostatic forces in a regular repeating lattice structure.

Question 2

Ionic compounds charge

Answer 2

Have no charge so the formula of ionic compounds contain the same number of positive and negative charges.

Question 3

What are polyatomic ions?

Answer 3

Ions that contain more than one atom e.g. sulphate ion( 1 sulphur atom bonded with 4 oxygen atoms).

Question 4

‘-ate’ or ‘-ite’

Answer 4

Shows the ion contains oxygen as well as another element.

Question 5

Melting and boiling points of ionic compounds

Answer 5

Require a lot of energy to overcome the strong electrostatic forces between the oppositely charged ions (and separate the ions) so the melting and boiling points are very high.

Question 6

For a substance to conduct electricity:

Answer 6

It must have charged particles.

These particles must be free to move.

Question 7

Can ionic compounds conduct electricity?

Answer 7

They only conduct electricity when molten or dissolved in water (aqueous solution/ electrolysis) because as a solid, their electrons aren’t delocalised (aren’t free to move) as the lattice is so tightly packed.

Question 8

What’s the negative ion called and what electrode is it attracted to?

Answer 8

Negative ion- anion

Attracted to positive electrode- anode

Question 9

What’s the positive ion called and what electrode is it attracted to?

Answer 9

Positive ion- cation

Attracted to negative electrode- cathode

Question 10

Molecular substances

Answer 10

Groups of atoms joined together by strong covalent bonds

Question 11

Atoms in molecules

Answer 11

Held together by strong electrostatic forces of attraction between positive nucleus and negative electrons.

Question 12

Forces of attraction between molecules

Answer 12

Very weak

Question 13

Valency of an element

Answer 13

Number of covalent bonds formed by atoms of different elements.

Question 14

Structure of molecules

Answer 14

Covalent, simple molecular structures e.g. water

Question 15

Melting and boiling points of molecular substances

Answer 15

Covalent bonds are strong forces of attraction but weak intermolecular forces. Low melting and boiling points because it doesn’t take much energy to overcome the weak intermolecular forces.

Question 16

Intermolecular forces

Answer 16

Hold molecules together (forces of attraction between molecules). Must be overcome when turning liquid to gas. (Water).

Question 17

Can simple molecules conduct electricity?

Answer 17

Simple molecules have no overall charge so can’t carry a current.
In covalent bonds electrons are shared between two atoms: Strong forces between negatively charged electrons and positively charged nucleus hold electrons in place so they can’t flow or carry a current.

Question 18

Polymers and monomers

Answer 18

Polymers are molecules made up of long chains of covalently bonded carbon atoms (polyethene).

Polymers are formed when lots of small molecules called monomers join together.

Question 19

Giant covalent structures properties

Answer 19

All atoms are bonded to each other by strong covalent bonds
Not soluble in water
Don’t conduct electricity because they don’t contain charged particles
Very high melting and boiling points

Question 20

Diamond

Answer 20

Carbon based giant covalent structure
Formed of a network of carbon atoms that each form four covalent bonds
High melting points
Strong covalent bonds hold atoms in a rigid lattice structure making diamond really hard- used to strengthen cutting tools
Doesn’t conduct electricity because there’s no free electrons or ions

Question 21

Graphite

Answer 21

Each carbon atom forms THREE covalent bonds-
Creating SHEETS of carbon atoms arranged in hexagons
NO COVALENT BONDS BETWEEN THE LAYERS so they’re only held together weakly and are free to MOVE OVER EACH OTHER-
So graphite is SOFT and SLIPPERY and is ideal as a LUBRICANT
HIGH melting point
3 of carbons 4 outer electrons are used in bonds so each carbon atom has ONE DELOCALISED electron.- so graphite can CONDUCT ELECTRICITY and is used to make ELECTRODES.

Question 22

Graphene

Answer 22

(type of FULLERENE) is ONE LAYER OF GRAPHITE
Sheet of carbon atoms joined together in hexagons
Sheet is ONE ATOM THICK making it a TWO- DIMENSIONAL compound

Question 23

Fullerenes

Answer 23

Molecules of carbon shaped like closed tubes or hollow balls
Mainly made up of carbon atoms arranged in hexagons but can also contain pentagons (rings of 5 carbons) or heptagons (rings of seven carbons)
Can be used to cage other molecules- this could be used to deliver a drug directly to cells in the body.
Huge surface area-
Could help make industrial catalysts by attaching individual catalyst molecules to the fullerenes

Question 24

Nanotubes

Answer 24

Fullerenes
Tiny cylinders of graphene so conduct electricity
High tensile strength (don’t break when stretched)-
So can be used to strengthen materials without adding much weight (sports equipment - tennis racket).

Question 25

Buckminsterfullerene

Answer 25

Molecular formula C60 Forms hollow sphere made up of 20 hexagons and 12 pentagons Stable molecule that forms soft brownish-black crystals

Question 26

Metallic bonding

Answer 26

Electrons in outer shell of metal atoms are delocalised Strong forces of electrostatic attraction between positive metal ions and shared negative electrons- These forces of attraction hold the atoms together in a regular Metallic bonding is very strong Compounds held together my metallic bonding - metallic elements and alloys

Question 27

Physical properties of metals

Answer 27

Electrostatic forces between metal ions and delocalised sea of electrons is very strong so need lots of energy to be broken- Very high melting and boiling points Shiny solids at room temp Not soluble in water More dense than non-metals as ions in metallic structure are packed close together Layers of atoms in pure metal can slide over each other making metals MALLEABLE- so can be hammered or rolled into flat sheets Delocalised electrons carry electrical current and thermal energy through the material- metals are good conductors of electricity and heat

Question 28

Difference between metals and non-metals

Answer 28

Physical properties: variety of different structures so have wide range of chemical and physical properties Dull looking, more brittle, lower boiling points, don’t often conduct electricity, lower density Chemical properties: Non metals tend to gain electrons to form full outer shells (right of periodic table) Metals lose electrons to gain full outer shell (left of periodic table)