C2 - Bonding, Structure And Properties Of Matter

Question 1

What are ions

Answer 1

They’re charged particles - single atoms or groups of atoms
When atoms lose or gain electrons they form ions
Loose electrons - positive ions
Gain electrons - negative ions

Question 2

Which groups are most likely to form ions

Answer 2

Groups 1,2,6,7 as they either need to gain or lose 1 or 2 electrons

E.g sodium atom loses 1 electron to form Na+ so it’s
Na -> Na+ + e-
Oxygen atom gains 2 electrons to form O2- so it’s
O + 2e- -> O2-

Question 3

What is ionic bonding

Answer 3

Transfer of electrons
When a non metal and metal react together, the metal atom loses electrons and the non metal gains them - these oppositely charged ions are attracted by electrostatic forces - ionic bond
Share electrons

Question 4

How to show ionic bonding

Answer 4

Dot and cross diagram - show arrangement of electrons in an atom or ion
One atom gives up an electron to the other atom so they both have a full outer shell
Dot and cross show how they’re formed, but not structure, size of ions or arrangement

Question 5

What are ionic compounds

Answer 5

Ionic compounds(have regular lattice structure) have a structure called a giant ionic lattice 
Ions Form closely packed regular lattice arrangement with very strong electrostatic forces of attraction between oppositely charged ions, In all directions of the lattice

Question 6

Different models for ionic compounds compounds

Answer 6

Ball and stick model - shows regular pattern of ionic crystal and shows how ions are arranged - not to scale - no gaps
Another model shows size and pattern of ionic crystal - only see outer
See notes for diagram

Question 7

Properties of ionic compounds

Answer 7

All have high melting/boiling points due to strong bonds between ions - lots of energy to overcome
When solid, ions are held in place - can’t conduct electricity
When melted, ions can flow and carry current
Dissolve easily in water - ions separate and flow

Question 8

How to find empirical Formular on an ionic compounds from diagram of compound

Answer 8

Dot and cross - count atoms of each element and write down for empirical Formular
3D Model - work out what ions are in the ionic compounds and balance charges of ions so overall charge of compound is 0

Question 9

What is covalent bonding

Answer 9

Sharing electrons (only outer shells) 
When non metals bond together, they share pairs of electrons to make covalent bonds

Question 10

Why are covalent bonds strong

Answer 10

Positive charged nuclei of bonded atoms are attracted to shared pair of electrons by electrostatic forces

Question 11

What does each single covalent bond provide

Answer 11

Provides one extra shared electron for each atom
Each atom involved makes enough covalent bonds to fill up its outer shell
Covalent bonding happens in compounds of non metals and non metal elements

Question 12

Different ways of drawing covalent bonds

Answer 12

Dot and cross - show bonding in covalent compounds. Electrons overlap and show which atom the electrons in a covalent bond comes from - no size or arrangement
Line model - displayed Formula and shows CB as a single line
Good for showing how atoms are connected in large molecules - no 3D structure or which atoms the electrons in the cb come from
3D Model - shows atom, CB and their structure - confusing for large molecules with lots of atoms. Doesn’t show where electrons in the cb came from

Question 13

What are simple molecular structures made up of

Answer 13

Made up of molecules containing few atoms joined with covalent bonds

Question 14

Common examples of simple molecular structures

Answer 14

Hydrogen H2- has 1 electron needs one more - form single cb
Chlorine Cl2- each Cl needs one more electron - two chlorine share one pair
Oxygen O2- needs 2 more electrons - share two pairs to form double cb
Nitrogen N2 - needs 3 more - 2 nitrogen share 3 pairs - triple bond
Methane CH4 - carbon has 4 - half - form 4 cb with hydrogen
Water H2O - oxygen shared pair with 2 hydrogen to form 2 single cb
Hydrogen chloride HCl - needs one more
See notes for diagrams

Question 15

Properties of simple molecular structures

Answer 15

Substances with covalent bonds normally have simple molecular structures
Atoms within molecules held together with very strong covalent bonds - forces of attraction are weak
Low melting/boiling as the forces of attraction are weak - particles easily separated
Most gases or liquid at room temperature
As molecules get bigger, their intermolecular forces increase - more energy to break
Don’t conduct electricity - no free electrons or ions

Question 16

What are polymers

Answer 16

Long chains of repeating units
Lots of small units linked together to form a long molecule
All atoms in a polymer are joined with covalent bonds

Question 17

How do you draw a polymer

Answer 17

Just draw the repeated section in brackets - bonds through brackets
See notes for diagram
‘n’ next to brackets represents how many repeats

Question 18

How to find molecular formula of a polymer

Write unit in bracket with n

Answer 18

For poly(Ethene) molecular formula is C2H4 
See notes for diagram

Question 19

Properties of a polymer

Answer 19

Intermolecular forces between polymer molecules are larger than the simple covalent molecules - more energy needed
Most polymers solid at room temperature
Intermolecular forces weaker than ionic or covalent bonds - lower boiling points

Question 20

How are atoms bonded in giant covalent structures

Answer 20

With strong covalent bonds

Question 21

What are giant covalent structures

Answer 21

They are macromolecules

Question 22

Properties of giant covalent structure

Answer 22

High melting/boiling points - lots of energy

Don’t contain charged particles - can’t conduct electricity, even when molten

Question 23

Examples of giant covalent structures (diamond, graphite, silicon dioxide)

Answer 23

Diamond - each carbon atom forms 4 cb in a very rigid giant covalent structure
Graphite - each carbon atom forms 3 cb to create w layer of hexagons
Each carbon atom has one delocalised (free) electron - can flow
Silicon dioxide - sometime scaled silica - what sand is made of - each grain of sand is one giant structure of silicon and oxygen

Question 24

What’s an allotrope

Answer 24

Different structural forms

Question 25

Properties of diamond

Answer 25

Diamond has a giant covalent structure made up of carbon stoke that form 4 cb- very hard
Strong cb take lots of energy to break - high melting point
Doesn’t conduct electricity - no free electrons or ions

Question 26

Properties of graphite

Answer 26

Each carbon atom forms 3 cb creating a sheet of carbon atom arranged as hexagons
No cb between layers - held weakly and free to move over - soft and slippery - lubricating material
High melting point - cb in lagers need lots of energy to break
Can conduct electricity due to delocalised electron

Question 27

What is Graphene and properties

Answer 27

Graphene is one layer of graphite
Still 3cb forming hexagons
CB make it strong. Very light - added to composite materials to improve strength without adding weight
Still conduct electricity due to delocalised electron

Question 28

What are fullerenes

Answer 28

Fullerenes form spheres and tubes
They’re molecules of carbons shaped like tubes or hollow balls
Carbon atoms arranged as hexagons, but can contain pentagons or heptagon

Question 29

Properties/uses of fullerenes

Answer 29

Used to cage other molecules - structure forms around other atom or molecule - deliver drug in body
Huge surface area - good industrial catalyst
Good lubricants
Fullerenes form nanotubes - tiny carbon cylinders - conduct electricity and thermal
High tensile strength (strength when stretched)
‘Nanotechnology’

Question 30

What does metallic bonding involve

Answer 30

Involves delocalised electrons

Metals consist of a giant structure

Question 31

What is metallic bonding

Answer 31

Strong electrostatic forces of attraction between positive metal ions and negative share electrons
Hold atoms together in a regular structure

Question 32

What substances are held together by metallic bonding

Answer 32

Metallic elements and alloys

Question 33

What produces all the metals properties

Answer 33

Delocalised electrons in the metallic bonds

Question 34

Properties of most metals

Answer 34

Electrostatic forces between metal atoms and delocalised sea of electrons are very strong - high melting/boiling point
Metals area good conductors of electricity and heat
Delocalised electron can carry current and thermal energy through whole structure
Metals are malleable - layers of atoms in metals can slide over each other

Question 35

What are alloys

Answer 35

Alloys are harder than pure metals as they’re a mixture of two or more metals of metal and another element (pure metals are too soft)

Question 36

What makes alloys harder

Answer 36

As the different elements are different sized atoms, an element mixed with a pure metal will distort layers meaning it’s harder to slide over each other
See notes for diagram

Question 37

Properties of solid

Answer 37

Strong forces of attraction between particles - held in fixed positions to form regular lattice structure - vibrate around fixed positions - definite shape

Question 38

Properties of liquid

Answer 38

Weak forces of attraction
Randomly arranged and free to move but close together
Definite volume but no definite shape
Constant movement in random directions

Question 39

Properties of gas

Answer 39

No forces of attraction
Free to move and far apart
Constantly moving at random directions quickly
No definite shape or volume
Hotter = faster and more pressure or expansion

Question 40

What’s aqueous

Answer 40

Dissolved in water

Question 41

Name the changes of state

Answer 41

Solid > gas sublimation 
Gas > solid decomposition 
Solid > liquid melting 
Liquid > solid freezing 
Gas > liquid condensing 
Liquid > gas boiling/evaporating