always less than its atomic number, the sum of the number of protons and neutrons present in the nucleus, always more than the atomic weight, a fraction" /> always less than its atomic number, the sum of the number of protons and neutrons present in the nucleus, always more than the atomic weight, a fraction" /> always less than its atomic number, the sum of the number of protons and neutrons present in the nucleus, always more than the atomic weight, a fraction" />