Atomic Structure - IGCSE Edexcel Chemistry

Nucleus

Center of an atom

Electron

A subatomic particle that has a negative charge

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

atomic number

the number of protons in the nucleus of an atom

mass number

the sum of the number of neutrons and protons in an atomic nucleus

electron shell

An energy level representing the distance of an electron from the nucleus of an atom.

Atomic number = 11

This atom has 11 protons and 11 electrons

Mass number = 19, Atomic no. = 9

This atom has 9 protons, 9 electrons and 10 neutrons

Mass number = 12, atomic no. = 6

This atom has 6 protons, 6 electrons and 6 neutrons

Atomic no. = 13, Mass number = 27

This atom has 13 protons, 13 electrons and 14 neutrons

Atomic no. =3, Mass number = 7

This atom has 3 protons, 3 electrons and 4 neutrons

Isotopes

Atoms with the same number of protons but different numbers of neutrons

Relative mass of proton / neutron

1

Relative mass of electron

1/1840

Relative charge of proton

+1

Relative charge of neutron

0 (neutral)

Relative charge of electron

-1

Isotopic abundance

the percentage of a given isotope in a sample of an element

Atomic no. = 26, Mass no. = 56

26 protons, 26 electrons and 30 neutrons