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Group (Chemistry)

Key Stage 3

Meaning

A Group is a column on the Periodic Table with elements with the same number of electrons on the Outer Shell.

About Groups

Helium, in Group 0 is an exception to this rule as it has 2 electrons in its Outer Shell.
The elements are arranged groups of similar chemical properties.
Elements have similar chemical properties when they have the same number of electrons in the Outer Shell.
PeriodicTableGroups.png

Trends within groups

The chemical properties of elements within a group are similar. However, the reactivity within a group changes as you move up or down the periods.

The physical properties of elements within a group are similar. However, the property changes gradually as you move down the group.

Key Stage 4

Meaning

A Group is a column on the Periodic Table with elements with the same number of electrons on the Outer Shell.

About Groups

Helium, in Group 0 is an exception to this rule as it has 2 electrons in its Outer Shell.
The elements were oringally arranged groups of similar chemical properties.
It was later discovered that elements have similar chemical properties when they have the same number of electrons in their Outer Shells.
PeriodicTableGroups.png

Trends within groups

The chemical properties of elements within a group are similar. However, the reactivity within a group changes as you move up or down the periods due to the number of Electron Shells.

Group 1: The Alkali Metal

Chemical Properties
Alkali Metals are all highly reactive and will oxidise quickly in the presence of Oxygen.
Alkali Metals all react strongly with water to produce metal hydroxides and Hydrogen gas.
Alkali Metals all produce strong alkalis.
Group1ElectronShells.png
In a chemical reaction the electron in the outer shell is lost.

The reactivity increases as you go down the group because:

Physical Properties
Alkali Metals have a low density compared to other metals.
Alkali Metals are all solid at room temperature but have a low melting point compared to other metals.
Alkali Metals are soft and can be easily cut.
Alkali Metals all appear shiny (before they oxidise).

Group 7: The Halogens

Chemical Properties
The reactivity of Halogens decreases as you go down the Periodic Table.
Halogens all react strongly as bleaching agents.
Halogens all produce acids when combined with Hydrogen.
Halogens are toxic to bacteria and are used in disinfectants.
Group7ElectronShells.png
In a chemical reaction an extra electron is added to the outer shell.

The reactivity decreases as you go down the group because:

Physical Properties

The physical properties of Halogens changes significantly as you go down the Periodic Table:

The density, melting point and boiling point all increase as you go down the Periodic Table.

Group 0: The Noble Gases

Chemical Properties
The Nobel Gases are all inert (unreactive) because they have a full outer shell.
Physical Properties
The Nobel Gases are all gases at room temperature.
The density and boiling point all increase as you go down the Periodic Table.

References

Edexcel

Groups (of the periodic table), page 173, GCSE Combined Science, Pearson Edexcel
Groups (of the periodic table), page 29, GCSE Chemistry, Pearson, Edexcel
Groups (of the periodic table); group 0 elements, pages 134-135, GCSE Chemistry, Pearson, Edexcel
Groups (of the periodic table); group 0 elements, pages 248-249, GCSE Combined Science, Pearson Edexcel
Groups (of the periodic table); group 1 elements, pages 128-129, GCSE Chemistry, Pearson, Edexcel
Groups (of the periodic table); group 1 elements, pages 242-243, GCSE Combined Science, Pearson Edexcel
Groups (of the periodic table); group 7 elements, pages 130-131, 132-133, GCSE Chemistry, Pearson, Edexcel
Groups (of the periodic table); group 7 elements, pages 244-245, 246-247, GCSE Combined Science, Pearson Edexcel
Groups (of the periodic table); valency, page 185, GCSE Combined Science, Pearson Edexcel
Groups (of the periodic table); valency, page 41, GCSE Chemistry, Pearson, Edexcel
Groups (periodic table), pages 81-83, 123, 124, 126, GCSE Combined Science; The Revision Guide, CGP, Edexcel
Groups, pages 18-20, 73, 74, 76, GCSE Chemistry; The Revision Guide, CGP, Edexcel

OCR

Groups (in the periodic table), pages 87-89, 121-125, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
Groups, pages 16-18, 51, 52, 54, Gateway GCSE Chemistry; The Revision Guide, CGP, OCR