2.15 Understand these displacement reactions as redox reactions.

When a more reactive halogen displaces a less reactive halogen, it's called a redox reaction. This is because an element has gained something and the other has lost something:

OIL RIG:
Oxidisation
Is
Loss (of electrons)
Reduction
Is
Gain (of electrons)

2.14 Describe experiments to demonstrate that a more reactive halogen will displace a less reactive halogen from a solution of one of its salts

A more reactive halogen will displace a less reactive one in a solution of its salt but only if the salt is dissolved in water or a gas.

Eg. if chlorine (Cl) is added to a solution of sodium bromide, it will form a solution of sodium chloride instead, and bromine will become a 'waste' product.

The balanced equation would be:

Cl₂ + 2NaBr → 2NaCl + Br₂

2.13 Describe the relative reactivities of the elements in Group 7

The further down the group you go, the less reactive the substance (note that astatine is radioactive and very rare....)

2.12 Explain, in terms of dissociation, why hydrogen chloride is acidic in water but not in methylbenzene

See also 2.11

Basically, the ions dissociate (split up) into Cl^- and H⁺ , making it acidic because of the H⁺ ions. This only happens in water.

In methylbenzene, the ions do not dissociate, and so hydrogen chloride does NOT become acidic ^_^

2.11 Understand the difference between hydrogen chloride gas and hydrochloric acid

Hydrogen chloride gas is HCl_(g)
When dissolved in water, it becomes HCl_(aq) because the ions become detached: they dissociate, leaving separate H⁺ and Cl^- ions. H⁺ is acidic, which is what makes it an acid :)

2.10 Make predictions about the properties of other halogens in this group

As you go down the group:

• Reactivity decreases
• Color darkens
• Melting/boiling point increases
• Particles become closer together (i.e. fluorine is a gas but astatine is a solid)

Figure 1: Fluorine at room temperature, in a bottle (it is a highly toxic gas after all!)

2.9 Recall the colours and physical states of the elements at room temperature

Fluorine (F)

• Gas
• Yellow

Chlorine (Cl)

• Gas
• Yellow-green

Bromine (Br)

• Liquid
• Brownish red

Iodine (I)

• Solid
• Purple

Astatine (At)

• Solid
• Black

2.8 Explain the relative reactivities of the elements in Group 1 in terms of distance between the outer electrons and the nucleus.

Group 1 elements only have 1 electron in their outer shell. Electrons are held to the atom by the forces of attraction between the nucleus (which has protons, so a positive charge) and the electrons themselves (which have a negative charge). If there are more shells, the last electron (which will be lost if the metal reacts with anything)  is further away from the nucleus, so the forces of attraction between the nucleus and the electron are weaker. The more shells, the further away, and it's more reactive.

As you go down the group, they become more reactive because there is an increase in the number of shells :)

(Does this make sense or am I talking gibberish?)

2.7 Describe the relative reactivities of the elements in Group 1

As you go down the group, the metals become more reactive.

2.6 Describe the reactions of these elements with water and understand that the reactions provide a basis for their recognition as a family of elements

By "these elements", they mean group 1 metals.

Lithium (Li), Sodium (Na) and Potassium (K) all react vigorously with water. The rest further down the group...well...it's probably not safe to experiment with those in a lab (or anywhere, really...)

Lithium

• Floats
• Fizzes
• Solid eventually disappears
• Produces some heat but doesn't melt

Sodium

• Floats
• Heat given off, causing it to melt into a ball
• Gradually disappears
• Sometimes a white trail of sodium hydroxide can be seen, but it usually ends up dissolved in the water
• Moves around (due to hydrogen given off)
• If it gets stuck on the side of the container, it will burn with an orange flame.

Potassium

• Burns with a lilac flame
• Reacts similarly to sodium but quicker
• Gives off heat, causing it to melt into a ball

As you go down the group, the reactions become more vigorous. There's plenty of videos on YouTube :) (even of the super reactive ones...they're pretty impressive)

2.5 Understand that the noble gases (Group 0) are a family of inert gases and explain their lack of reactivity in terms of their electronic configurations.

They're lazy. (Just kidding!)

Elements in group 0 (Aka group 8) don't react because their outer shells are already full. This means they don't need to react with any other elements - they're already stable!

2.4 Understand why elements in the same group of the Periodic Table have similar chemical properties

Elements in the same column have the same number of electrons in their outer shells. This means they react and bond similarly. This is because they need to lose or gain the same number of electrons to become stable and have full outer shells :)

2.3 Explain the classification of elements as metals or non-metals on the basis of their electrical conductivity and the acid-base character of their oxides

• Metals are conductors that form metal oxides that are alkaline
• (Most) non-metals are ones that don't conduct and form non-metal oxides that are acidic.

2.2 Recall the positions of metals and non-metals in the Periodic Table

See that red line?
Left = metals
Right = non metals
It's as simple as that!

The group of elements between group 1 and group 3 are called the transition metals. They don't tend to follow normal patterns and don't have a group number.

2.1 Understand the terms group and period

The group is the column (These are labelled by numbers, i.e. groups 1-8, also known as groups 1-0)
The period is the row. 

Figure 1: (I)GCSE periodic table

1.15 Deduce the number of outer electrons in a main group element from its position in the Periodic Table.

See 1.14, but basically the group number is the number of electrons in the outer shell.

1.14 Deduce the electronic configurations of the first 20 elements from their positions in the Periodic Table

The group number is the number of electrons in the outer shell. The atomic number is the number of protons, which is equal to the number of electrons (the charges need to balance each other out to make the atom neutral). It’s helpful to know that the first shell holds 2 electrons, the second holds eight, and the third holds eight as well. You can start filling up shell 4 if necessary but you don’t need to know how many this shell holds. So for example, Oxygen has an atomic number of 6 (and it’s in group 6) so its electronic configuration is…

2, 4

1.13 Understand that the Periodic Table is an arrangement of elements in order of atomic number

The periodic table lists all the elements that have ever been discovered, in order of atomic number. A row is called a period and a column is called a group.