Electron shells

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Electron shells

More reactive metals are to the right of the periodic table. The metals are also more reactive as you go down a group. e.g. Fr is more reactive than Li.

For non metals group 0 is unreactive (inert gases). Further up and further right the more reactive the non metal.

9

Be 9 - 4 = 5 neutrons

4

Electrons are arranged in shells around the nucleus. A maximum number of electrons are allowed n each shell and the shells must be filled up from the inner shells first. The first shell only has 2 electrons but the other shells can have a maximum of 8 electrons in each shell. To find out how many electrons are in an element you look at the atomic number.

e.g. 32

S (2,8,6) (2 electrons in the first shell, 8 electrons in the second shell and 6 electrons in the third shell)

16

Examples:

C =

6

Mg =

12

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