Year 9 MYE Atoms + Ions

Element

Made of only one type of atom

Atomic number

Number of Protons in an atom

Mass number

Number of Protons and Neutrons in an atom

Valence shell

The outermost shell of an atom

Valence electron

Electrons found in the outermost shell of an atom

Nucleus

Central part of an atom that contains the protons and neutrons

Electrons

Negatively charged subatomic particles

Proton

Positively charged subatomic particles

Neutron

Neutral subatomic particles

Ion

An atom that has gained or lost electrons to become charged

Charge of electron

Negative charge

Charge of proton

Positive charge

Charge of neutron

No charge

Mass of proton

1

Mass of neutron

1

Mass of electron

None

Why do atoms react to form Ions?

To become stable

How many electrons can each shell hold?

2 in the first shell, 8 in the second shell, 8 in the third shell