Contents
Key Stage 3
Meaning
The Periodic Table is a chart listing all the known elements arranged in order of Atomic Number and in columns of elements with similar properties.
About The Periodic Table
- The modern Periodic Table was arranged by a scientist called Mendeleev. Others had tried to arrange all the elements before, but Mendeleev was the first to arrange by both Atomic Number and chemical properties.
- The columns of the Periodic Table are called Groups.
- The rows of the Periodic Table are called Periods.
Groups
- 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.
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.
- Group 1: The Alkali Metals all react strongly with water. The reactivity increases as you go down the group.
- Group 2: The Alkali Earth Metals all react strongly with steam and acids. The reactivity increases as you go down the group.
- Group 7: The Halogens all act as bleaching agents and kill bacteria. The reactivity decreases as you go down the group.
- Group 0: The Noble Gases are all inert (unreactive).
The physical properties of elements within a group are similar. However, the property changes gradually as you move down the group.
Periods
- The periods are arranged by the number of Electron Shells.
Trends within Periods
- The chemical and physical properties of elements change as you move along a period.
Period 2 Melting Points | Period 3 Melting Points |
There is a trend in the Melting Points as you move along the period. | A similar trend can be seen in the next period. |