Ionic Bonding

Question 1

What does the perfect ionic model state?

Answer 1

Ionic compounds are composed of perfectly spherical cations and anions arranged in a lattice.

Question 2

What is ionic bonding?

Answer 2

Many strong electrostatic forces of attraction formed between oppositely charged ions (all the cations and anions) in a lattice.

Question 3

What is the relationship between electrostatic forces of attraction and ionic bonding?

Answer 3

The stronger the attraction, the stronger the ionic bonding.

Question 4

How would non-metals on their own be identified as?

How would you say these?
F⁻
Se²⁻
P³⁻
N³⁻
Br⁻
S²⁻
As³⁻

Answer 4

you add the suffix ‘-ide’ at then end of the substance name.

F⁻ > fluoride
Se²⁻ > selenide
P³⁻ > phosphide
N³⁻ > nitride
Br⁻ > bromide
S²⁻ > sulfide
As³⁻ > arsenide

Question 5

What is a polyatomic ion? Give an example.

Answer 5

When an ion is made up of one or more atom.

MnO₄⁻ > manganate ion

Question 6

What does empirical mean?

Answer 6

‘Experimental’

Question 7

Describe why an ionic compound can or cannot carry charge in either solid, liquid or gas state.

Answer 7

Solid =
Ions are not free to move - cannot carry charge - can’t conduct electricity.

Liquid =
Ions are free to move - can carry charge - can conduct electricity.

Gas =
Ions are separated and exist as ion pairs - cannot carry charge - cannot conduct electricity.

Question 8

What does the term ‘isoelectronic’ mean? Give examples.

Answer 8

When ions have an equal number of electrons.

E.G… these ions all have 10 electrons in total.
Na⁺
Mg²⁺
Al³⁺
N³⁻
O²⁻
F⁻

‘Iso’ is Greek for ‘equal’.

Question 9

For isoelectronic ions, how can we identify the smallest ion?

Answer 9

The larger the nuclear charge, the smaller the ion.

Question 10

Which ionic compound do we expect to have a higher melting point and why?

NaCl or KCl?

Answer 10

NaCl

because sodium has the same charge as potassium, but is smaller in size so there is a stronger electrostatic force of attraction and thus stronger ionic bonding, requiring more energy to overcome.

Question 11

Draw a diagram to show the structure of an ionic compound.

Answer 11

Ionic lattice = (Need AT LEAST 9 ions)

Oppositely charged ions in a 9x9 structure.
Anions are bigger than cations.
Include 1+,2+ / 1-, 2- charges in the circles.
Label which circles are the metal / non-metal.

Question 12

Draw a diagram to show the structure of a metallic substance.

Answer 12

Metallic lattice = (Need AT LEAST 9 ions)

9x9 positive ions next to each other.
Include 1+ / 2+ / 3+ in the circles.
For each ion, show the delocalised electrons around it.

E.G.
Mg2+ has 2 delocalised electron per ion. So in a 9x9 I would draw 18 electrons.

Question 13

List everything about ionic bonding you can remember.

Answer 13

Metal & non-metal - forms cations/anions.

ALL ionic compounds form a GIANT IONIC CRYSTAL LATTICE structure.
MANY STRONG electrostatic forces of attraction.
Electrons are TRANSFERRED.

Question 14

What are the properties of ionic compounds?

Answer 14

High melting / boiling point
Brittle
Soluble in water

Can conduct electricity when molten or aqueous
Cannot conduct electricity when solid.

Question 15

Why do ionic compounds have high melting and boiling points? [2 marks]

Answer 15

There are MANY STRONG electrostatic forces of attraction BETWEEN oppositely charged ions in the IONIC LATTICE - needs a lot of energy to overcome these attractions.

Question 16

Why are ionic compounds brittle? [2 marks]

Answer 16

When a horizontal FORCE is applied to lattice, the LAYERS of ions move and SLIDE over each other.

Ions of same charge are next to each other, so they REPEL each other and the crystal breaks up.

Question 17

Why can ionic compounds conduct electricity when molten or in solution? [2 marks]

Answer 17

Ions are free to MOVE THROUGH the substance, meaning ions are able to carry CHARGE and conduct electricity.

Question 18

Why are ions arranged in an ionic lattice structure?

Answer 18

To optimise the number of electrostatic forces of attraction.

Question 19

How are cations formed?

Answer 19

When a metal loses an electron.

Question 20

How are anions formed?

Answer 20

When a non-metal gains an electron.

Question 21

Which cation is the only non-metal?

Answer 21

Ammonium (NH₄⁺)

Question 22

What is a compound ion? Give examples.

Answer 22

An ion made up of a group of atoms.

E.G.
Ammonium
Sulfate
Nitrate
Carbonate
Hydroxide

Question 23

What does ‘monoatomic’ mean?

Answer 23

Consisting of only 1 atom.

Question 24

What is the definition of a ‘crystal’?

Answer 24

The ordered arrangement of ions in a material.

Ionic compounds are crystals.

Question 25

How can an ionic lattice be broken up?

Answer 25

Physical stress - (lattice bonds broken by force).

Dissolving - (into water).

Heating - (atoms vibrated apart).

Question 26

When discussing MP/BP ALWAYS mention…

Answer 26

1# Attractions / bonding.
2# Structure (lattice).
3# Energy to overcome forces.

Question 27

Explain, in terms of electrons, how Na₂S is formed from its atoms. [2 marks]

Answer 27

1 electron from each Na atom is transferred to the S atom.
The S atom accept 2 electrons from both Na.

Question 28

What is an ion?

Answer 28

When an tom loses or gains one or more electrons and becomes positively/negatively charged.

Question 29

What is a positively charged ion and negatively charged ion called?

Answer 29

Positively charged ion = cation

Negatively charged ion = anion

Question 30

What is a molecular ion? Give an example.

Answer 30

When 2 or more ions are bonded by a covalent bond.

E.G.

SO₄²⁻