Chemistry Revision

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ATOMS AND ELEMENTS

Atoms are tiny particles.

The nucleus contains protons and neutrons.

Protons - Positive Charge

Neutrons - Neutral Charge

Electrons - Negative Charge

If a substance only contains one type of atom its called an element.

Different elements have atoms with differents numbers of protons.

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THE PERIODIC TABLE

This symbol is magnesium

The atomic number is 12 because there are 12 protons in an atom of magnesium.

The mass number is 24 because there are 24 protons and neutrons in total in an atom of magnesium.

You can find out the neutron numbver by subtracting the atomic number by the mass number.

All of the elements in a group have the same number of electrons in their outer shell.

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