FLASH - GCSE Chemistry 5.2.1 - Chem. Bonds, Ionic, covalent & Metallic

Question 1

What is ionic bonding?

Answer 1

Ionic bonding is the electrostatic attraction between positive and negative ions.

It is a relatively strong attraction.

Question 2

How are ionic compounds
held together?

Answer 2

● They are held together in a giant lattice.
● It’s a regular structure that extends in all directions in a
substance.
● Electrostatic attraction between positive and negative ions holds
the structure together.

Question 3

State properties of ionic
substances

Answer 3

● High melting and boiling point (strong electrostatic forces between oppositely charged ions)
● Do not conduct electricity when solid (ions in fixed positions).
● Conduct when molten or dissolved in water - ions are free to move.

Question 4

Give 5 examples of positive ions and
5 examples of negative ions.

What is important when working out
a formula of an ionic compound?

Answer 4

E.g. Positive: Na⁺, Mg²⁺, Al³⁺, Ca²⁺, Rb⁺,

E.g. Negative: Cl⁻, Br⁻, SO₄ ²⁻,
NO₃⁻, OH⁻ (chloride, bromide, sulfate, nitrate, hydroxide).

Ionic compounds are electrically neutral, i.e. positive and negative charges balance each other.

Question 5

How are ionic compounds
formed? Explain in terms of
MgO case.

Answer 5

Reaction of a metal with a non-metal.

Electron transfer occurs - metal gives away its outer shell electrons to non-metal.

Mg is in Group II, so has 2 available outer shell electrons.
O is in Group VI, so can accept 2 electrons to get a full outer shell
configuration.
Mg becomes Mg²⁺ and O becomes O²⁻ (oxide).

Question 6

What is a covalent bond?

Answer 6

Covalent bond is a shared pair of electrons between two atoms.

Question 7

Describe the structure and
properties of simple molecular
covalent substances

Answer 7

• Do not conduct electricity (no ions)
• Small molecules
• Weak intermolecular forces, therefore:
• Low melting and boiling points

Question 8

How do intermolecular forces
change as the mass/size of the
molecule increases?

Answer 8

They increase. That causes melting/boiling points to increase as well (more energy needed to overcome these forces).

Question 9

What are polymers? What are
thermosoftening polymers?

Answer 9

Polymers are very large molecules (>100s, 1000s of atoms) with atoms linked by covalent bonds.

Thermosoftening polymers - special type of polymers; they melt/soften when heated. There are no bonds between polymer chains. Strong intermolecular forces ensure that the structure is solid at room temperature. These forces are overcome with heating - polymer melts.

Question 10

What are giant covalent
substances? Give examples

Answer 10

• Solids, atoms covalently bonded together in a giant lattice.
• High melting/boiling points – strong covalent bonds.
• Mostly don’t conduct electricity (no delocalised e−)
• Diamond, graphite, silicon dioxide.

Question 11

Describe and explain the
properties of allotropes of carbon.

Answer 11

Question 12

What is metallic bonding?

Answer 12

Forces of attraction between delocalised electrons and nuclei of metal ions.

Question 13

What are alloys? Why are
they harder than pure
metals?

Answer 13

Alloys:-
* mixtures of metal with other elements, usually metals-
* different sizes of atoms distorts the layers, so they can’t slide over each other, therefore alloys are harder than pure metals

Question 14

Describe properties of
metals

Answer 14

• High melting/boiling points (strong forces of attraction)
• Good conductors of heat and electricity (delocalised electrons)
• Malleable, soft (layers of atoms can slide over each other whilst maintaining the attraction forces)