An atom is the smallest part of an element which still retains the of that element.
Atoms are made up of three basic particles, the proton, neutron and the .
Protons have a positive charge and are located in the of the atom.
have no charge, and are also to be found in the nucleus.
Electrons have a charge and are found orbiting around the nucleus.
Protons and neutrons have a mass of atomic mass unit (a.m.u.).
Electrons have a much mass than a proton or neutron.
The number of electrons in an atom of an element is equal to the number of in the same atom.
The number of an element is equal to the number of protons in an atom of that element.
The number of an atom is equal to the sum of the number of protons and neutrons in that atom.
The number of neutrons is calculated by the atomic number from the mass number.