What is the atomic mass of silver?

According to Dalton’s atomic theory, an atom is the smallest unit or building block of matter. Later discoveries showed atoms contain subatomic particles: electrons, protons, and neutrons.

Subatomic Particles & Arrangement

• Electrons (negative) occupy orbitals around the nucleus.
• Protons (positive) and neutrons (neutral) reside in the dense, central nucleus.
• In a neutral atom, number of protons = number of electrons.

Atomic Number and Atomic Mass

Atomic number Z = number of protons.

Atomic mass is essentially the total mass of protons and neutrons in the nucleus (electron mass is negligible). Each proton or neutron ≈ 1 amu.

Atomic mass ≈ (Number of protons + Number of neutrons) × 1 amu

Example: Calcium

• Atomic number of Calcium (Z): 20 → 20 protons.
• Number of neutrons (common isotope): 20.
• Total nucleons = 20 + 20 = 40.

Hence, the atomic mass of calcium ≈ 40 amu.