Atoms Into Ions

Question 1

What happens when you mix two substances together?

Answer 1

They can form a mixture without either substance changing eg sand or copper
Or there can be a chemical reaction when the atoms of two or more elements react chemically they make a compound. It is difficult to return compounds to their original elements.
Compounds can also react together to form other compounds

Question 2

What are the noble gases?

Answer 2

Group 0 elements
Unreactive inert because they all have full outer shells of electrons
All atoms are neutral because they have the same number of protons and electrons

Question 3

What happens with other elements?

Answer 3

They all react because they are trying to achieve a full outer shell of electrons and gain noble gas structure

Question 4

How do elements react?

Answer 4

They gain, lose or share electrons
Eg lithium - atomic number 3, mass number 7
It has two shells of electrons with 2 on the first and then 1 on the second
It wants to lose 1 or gain 7 to have a full outer shell

Question 5

What is an ion?

Answer 5

The atoms that lose or gain electrons to have electronic structure of a noble gas have become charged particles called ions

Question 6

What is the pattern with metals and non metals?

Answer 6

Non-metals always gain electrons to become negative ions
Metals always lose electrons to become positive ions
The maximum is 2 on the inner shell, 8 on the two outer shells and then 18 on the last outer shell

Question 7

Why are metals and non metals attracted to each other?

Answer 7

They are opposites so they have electrostatic attraction
Metals become positive ions
Non-metals become negative ions
They often transfer electrons or share electrons with each other

Question 8

What is ionic bonding?

Answer 8

When atoms transfer electrons

Question 9

What happens in a covalent bond?

Answer 9

Atoms share electrons

Question 10

What is an ionic charge compound?
How is it written?
What are the rules of ionic formulae?
What is the overall charge?

Answer 10

1. An ionic compound is made up of a metal and a non-metal
2. The metal is written first
3. Each compound is made up of ions with charges but the formulae never shows the charges
4. Overall charge must be zero

Question 11

When do we use Roman numerals?

Answer 11

Transition metals can make a variety of positive ions
Eg copper can be Cu+ or Cu-
So copper (i) oxide comprises Cu+ and O2- so the formula is Cu2O
Copper (ii) oxide comprises Cu2+ and O2- formula CuO

Question 12

What are the features of ionic compounds?
How are they arranged?
Solubility, conductivity, melting and boiling points?

Answer 12

1. Ions are arranged in a giant lattice
2. Ionic bonds act in all directions making them very strong. This means they have high melting and boiling points because a lot of energy is needed to weaken or break the many strong ionic bonds between the positive and negative ions
3. Soluble in water - adding water breaks bonds in lattice
4. Conduct electricity - ionic solids contain charged ions but they are fixed so don’t conduct electricity. Instead if melted or dissolved in water the ions are mobile and carry charge eg molten zinc chloride

Question 13

What is covalent bonding?

Answer 13

Covalent bonding occurs between non metals - can be same non metal
Can’t both gain/lose electrons - SHARE NOT TRANSFER
Only draw the outer shell - Only outer shell changes
hydrogen shares 1, oxygen shares 2, nitrogen shares 3

Question 14

Explain covalent bonding in compounds?

Answer 14

Simple molecules eg methane CH4
Carbon has 4 electrons in outer shell so 4 hydrogen atoms to make it complete
Ammonia NH3 - nitrogen has 5 in outer shell so 3 hydrogen atoms to make it complete

Question 15

What are the properties of simple covalent molecules?

Answer 15

1. Most are liquid or gas at room temperature
2. Low melting and boiling point because of weak intermolecular forces
3. Insoluble in water
4. There are no charged ions so they don’t conduct electricity

Question 16

Why can’t 2 chlorine atoms form an ionic bond together?

Answer 16

Both non metal
2 chlorine both need to gain electrons so they don’t attract because they are not opposites and both need same amount of electrons
Can only work if covalent - share one outer electron so both have 8

Question 17

Give examples of giant covalent structures?

Answer 17

Diamond - carbon atom uses all 4 outer electrons to make 4 covalent bonds
Graphite - carbon atom only uses 3 outer electrons to make 3 covalent bonds
Silica (SiO2) -
All atoms bonded in giant lattice
Join in hexagons and firm layers
In between layers are weak intermolecular forces
In graphite the spare electron is delocalised
Bonds are very strong so high melting and boiling point

Question 18

What are the properties of giant covalent structures (graphite)?

Answer 18

Slippery - layers can slide past each other, weak intermolecular forces between layers
Conduct electricity across layers because delocalised electron can move and carry charge but can’t move to next layer

Question 19

What are allotropes?

What are the allotropes of carbon?

Answer 19

Different forms of the same element in the same state
Diamond
Graphite
Buckminsterfullerene
Graphene

Question 20

Features of diamond

Answer 20

Giant covalent bond
C4
Very high mpt and bpt
Difficult to break strong covalent bond
Insulator - no Delocalised electrons
Very hard and strong

Question 21

Features of graphite

Answer 21

Giant covalent bond
C3
Very high mpt and bpt
Difficult to break strong covalent bond
Conductor because delocalised electrons carry charge through structure
Soft and brittle
Slippery because there are no covalent bonds between layers only weak intermolecular forces and the layers can slide over each other

Question 22

Features of buckminsterfullerene

Answer 22

Simple molecular structure
C60 - 3
Not so high mpt and bpt
Easier to overcome relatively weak intermolecular forces between molecules - no covalent bonds broken
Insulator - delocalised electrons but can’t move from one molecule to another
Soft and brittle

Question 23

Features of graphene

Answer 23

Giant covalent bond 
C3 
Very high mpt and bpt
Difficult to break strong covalent bonds
Conductor as delocalised electrons carry charge through structure 
Very strong

Question 24

What are the features of ionic compounds?

Answer 24

High mpt and bpt
Does not conduct when solid
Conducts when molten/Liquid
And more

Question 25

Why is sea water a better conductor of electricity than fresh water

Answer 25

Sea water has charged ions in it
Fresh water doesn’t
You need ions to carry charge