An atom is the smallest part of an atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree which still retains the properties of that element. Atoms are made up of atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree basic particles, the atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree, neutron and the electron. Protons have a positive charge and are located in the atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree of the atom. atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree have no charge, and are also to be found in the nucleus. Electrons have a atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree charge and are found orbitting around the nucleus. Protons and neutrons have a mass of atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree atomic mass unit (a.m.u.). Electrons have a much smaller atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree. The number of atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree in an atom of an element is equal to the number of protons in the same atom. The atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree number of an element is equal to the number of atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree in an atom of that element. The atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree 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 subtracting the atomicatomic numberelectronselementmassmass numbernegativeNeutronsnucleusoneprotonprotonsthree from the mass number.