Ionic/ Covalent bonding

Question 1

What are ionic compounds?

Answer 1

• Ionic compounds are oppositelt- charged ions held together by strong electrostatic forces of attraction in a lattice.

Question 2

What is the formula of ammonium, carbonate, sulphate, hydroxide and nitrate ions?

Answer 2

-NH₄⁺
- CO₃²⁻
- SO₄²⁻
- OH⁻
- NO₃⁻

Question 3

What type of structure do ionic compounds form?

Answer 3

• Giant/ lattice ionic structure.

Question 4

When can ionic compounds conduct electricity/ why?

Answer 4

• When molten/ dissolved in solution.
• Because the ions are free to move around and carry the charge.

Question 5

Why do ionic compounds have high melting points?

Answer 5

• There are many strong electrostatic forces of attraction (throughout the structure) between oppositely-charged ions.
• These strong electrostatic forces require a lot of energy to break.

Question 6

Why can most ionic compounds dissolve in water?

Answer 6

• As water molecules are polar they can attract positive and negative ions (ie. split the ions apart in solution) to break the structure.

Question 7

Why are ionic compounds brittle?

Answer 7

• When the compound is hit, the layers shift so that like ions are vertically opposite one another.
• The like ions will repel one another, so, the ionic compound can easily break apart due to this repulsion.

Question 8

What 4 main properties do ionic compounds have?

Answer 8

1.) High melting point.
2.) Brittle.
3.) Conduct electricity (when molten/ dissolved in solution.)
4.) Dissolve in water.

Question 9

How should you draw dot and cross diagrams for ionic bonding?

Answer 9

• Metal ion (losing electrons): draw the next full outer shell only with its electrons (not all the inner shells.)
• Non- metal ion (gaining electrons): only draw the outermost shell (where electron is being gained.)

Question 10

What is a covalent bond?

Answer 10

• Covalent bond: shared pair of outer electrons.

Question 11

With what force are atoms with covalent bonds held together?

Answer 11

• Atoms with covalent bonds are held together by the electrostatic attraction between the shared pair of electrons and the positive nuclei.

Question 12

What are dative/ co-ordinate covalent bonds?

Answer 12

• This is where one atom donates a pair of electrons to another atom/ ion to form a bond.

Question 13

What are the pair of electrons donated in dative covalent bonding called?

Answer 13

• Called a lone pair.

Question 14

Give an example of dative covalent bonding.

Answer 14

NH₃ has lone pair of electrons. Donates this lone pair to H+ ion to form a dative covalent bond.

(diagram of this on chemistry file on laptop.)

Question 15

How are dative covalent bonds represented?

Answer 15

• Represented with an arrow: showing direction electrons have been donated in (ie. showing which atom donated the electrons.)

Question 16

Why do simple covalent molecules have low melting points?

Answer 16

• Weak intermolecular forces between molecules require little amount of energy to break.

Question 17

Why can’t simple covalent molecules concuct electricity?

Answer 17

• No charged ions/ delocalised electrons to carry the charge.

Question 18

What does a dative covalent bond contain?

Answer 18

• Contains a shared pair of electrons with both electrons supplied by one atom.