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Electron configuration, metals and non-metals
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The position of an element in the Periodic Table tells you its electron configuration and whether it is a metal.
Electron configuration and position
Electrons fill shells: 2 in the first, then 8, then 8 (for the first 20 elements).
The group number = the number of electrons in the outer shell (for groups 1 to 7).
The period number = the number of occupied shells.
Calcium (atomic number 20) is in period 4, group 2: 2.8.8.2.
The group number = the number of electrons in the outer shell (for groups 1 to 7).
The period number = the number of occupied shells.
Calcium (atomic number 20) is in period 4, group 2: 2.8.8.2.
Same group, similar properties
Elements in the same group have the same number of outer electrons, so they react in similar ways.
Group 0 elements have a full outer shell, so they do not readily react.
Group 0 elements have a full outer shell, so they do not readily react.
Metal or non-metal?
An element has electron configuration 2.8.6. Which group and period is it in, and is it a metal?
- 6 outer electrons, so group 6.
- 3 occupied shells, so period 3.
- Group 6 is on the right of the table.
Answer: Group 6, period 3; a non-metal (sulfur).
Group number = outer electrons; period number = shells. Elements in a group have similar properties because they have the same number of outer electrons. Metals conduct and have basic oxides; non-metals do not conduct (except graphite) and have acidic oxides.
The interactive lesson includes the diagrams for this topic.
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