Ionic Bonding

Question 1

What is ionic bonding

Answer 1

The transfer of electrons from a metal atom to a non-metal atom to form positive metal ions and negative non-metal ions. This results in strong electrostatic forces between oppositely charged ions in a lattice

Question 2

Which model is used to show ionic bonding

Answer 2

Dot-and-cross diagrams

Question 3

What is a lattice

Answer 3

Regular 3D repeating arrangement of ions in a crystal

Question 4

Which ions produce the strongest electrostatic attractions

Answer 4

Ions with high charges and small ionic radii(those with a high charge density)

Question 5

Which ions produce the weakest electrostatic attractions

Answer 5

Those with low charges and big ionic radii(low charge density)

Question 6

Do compounds with stronger or weaker ionic bonds have a greater solubility in water

Answer 6

Compounds with weaker ionic bonds-weaker force of electrostatic attraction between ions means these are easier to break apart

Question 7

Properties of ionic compounds

Answer 7

-hard and brittle
-high melting and boiling temperatures
-soluble in water and other polar solvents,insoluble in non-polar solvents

Question 8

When do ionic compounds conduct electricity and why

Answer 8

When melted or dissolved in water because charged ions are then free to move, when solid their ions cannot move away from fixed positions in the giant lattice

Question 9

What is electrolysis

Answer 9

The decomposition of a compound by electricity

Question 10

What is an electrolyte

Answer 10

The compound which is being decomposed by electrolysis, described as being electrolysed

Question 11

Which ions move towards the cathode and what happens there

Answer 11

Cations(positive ions) move towards the cathode(negative electrode) where they gain electrons to form their element

Question 12

Which ions move towards the anode and what happens there

Answer 12

Anions(negative ions) move towards the anode(positive electrode) where they lose electrons to form their element

Question 13

What evidence is there for ionic bonding

Answer 13

Can look at electron density maps (show likelihood of finding electrons in a region). Show electrons are discrete(separate) as electron density falls to zero between ions and ions are arranged in regular patterns (lattice structure)

Question 14

What does isoelectronic mean

Answer 14

When atoms/ions have the same number of electrons and so same electronic configuration

Question 15

How does the size of radius change when atoms form positive ions

Answer 15

Ionic radius for positive atoms is smaller than atomic radius as electrons are lost from its outer shell

Question 16

How does size of radius change when atoms form negative ions

Answer 16

Ionic radius of negative ions is greater than atomic radius as electrons are added to its outer shell

Question 17

How does ionic radius change down a group

Answer 17

Ionic radius increases as there are more electron shells meaning more shielding which decreases the attraction between nucleus and outer electrons and the outer electrons are not pulled in as much and more electron shells so ion bigger

Question 18

How does ionic radius change across period

Answer 18

Ionic radius decreases in size as number of protons increases while shielding does not increase significantly as electrons are added to the same shell meaning electron shells are pulled closer

Question 19

Why are ionic compounds soluble in water

Answer 19

Water molecules are polar meaning they can attract both positive and negative ions and break down the structure

Question 20

Why are ionic compounds brittle

Answer 20

When struck the layers slide so get positive ions aligned with positive ions and negative ions aligned with negative ions which repel each other meaning the structure breaks apart

Question 21

Why does a smaller ionic radii increase melting point

Answer 21

Stronger electrostatic attractions between ions as they can be packed together more closely meaning more energy is required to overcome stronger forces

Question 22

Evidence for ions from coloured ionic compounds

Answer 22

Electrolysis of coloured ionic compound on wet filter paper, ions will move towards electrode with opposite charge showing evidence for charged particles