What is atomic mass ? and …

Atomic Number

• The total number of protons in the nucleus of an atom gives us the atomic number of that atom.
• It is represented with the letter ‘Z.’
• All the atoms of a particular element have the same number of protons, and hence the same atomic number.
• Atoms of different elements have different atomic numbers.
• For example, all carbon atoms have the atomic number of 6, whereas all atoms of Oxygen have 8 protons in their nucleus.

Mass Number

• The number of protons and neutrons combined to give us the mass number of an atom.
• It is represented using the letter ‘A.’
• As both protons and neutrons are present in the nucleus of an atom, they are together called nucleons.
• For example, an atom of carbon has 6 protons and 6 neutrons. Thus, its mass number is 12.
• While the number of protons remains the same in all atoms of an element, the number of neutrons can vary. Thus, atoms of the same element can have different mass numbers, and these are called isotopes.