Neutron

Key Stage 4

Meaning

The Neutron is a neutral particle found in the nucleus of an atom.

About Neutrons

Neutrons are a type of nucleon.

Neutrons have a relative atomic charge of 0 and a relative atomic mass of 1.

The number of neutrons in an atom can be found subtracting the Atomic Number from the Relative Atomic Mass.

Hydrogen	Helium	Lithium	Beryllium
This atom has an Atomic Number (Z) of 1 and a Relative Atomic Mass (A) of 1. Number of neutrons = A - Z Number of neutrons = 1 - 1 Number of neutrons = 0	This atom has an Atomic Number (Z) of 2 and a Relative Atomic Mass (A) of 4. Number of neutrons = A - Z Number of neutrons = 4 - 2 Number of neutrons = 2	This atom has an Atomic Number (Z) of 3 and a Relative Atomic Mass (A) of 7. Number of neutrons = A - Z Number of neutrons = 7 - 3 Number of neutrons = 4	This atom has an Atomic Number (Z) of 4 and a Relative Atomic Mass (A) of 9. Number of neutrons = A - Z Number of neutrons = 9 - 4 Number of neutrons = 5

Key Stage 5

Meaning

A neutron (n) is a baryon made from 1 up-quark and 2 down-quarks.

About Neutrons

A neutron is one of two baryons found in the atomic nucleus.

Neutrons have a charge of zero and a mass of 1.67x10^-27kg.

A neutron is only stable in the nucleus of an atom. However a free neutron has a mean lifeftime of around 15 minutes before it decays via the weak interaction into a proton and an electron.

Subatomic Particle	Quark-composition	Charge/e	Strangeness	Baryon Number	Lepton Number
Neutron	\(udd\)	\(q=0\)	\(S=0\)	\(b=+1\)	\(l=0\)
Antineutron	\(\bar{u}\bar{d}\bar{d}\)	\(q=0\)	\(S=0\)	\(b=-1\)	\(l=0\)