no electrons have mass, about 1/1800 that of a proton or neutron.
The number of protons
21 protons, 21 electrons and 23 neutrons
ThalliumSymbol: TlAtomic Number: 81Atomic Mass: 204.3833 amuNumber of Protons & Electrons: 81Number of Neutrons: 123
No protons and neutrons
You add up the mass of the protons, neutrons, and electrons. Protons and Neutrons having an atomic mass of 1, and electrons having an atomic mass of roughly 1/1800.
Electrons have no relevant mass, and protons and neutrons both have the mass of 1u. If Calcium has the number 20, it has 20 protons (and electrons). It's mass is about 40u. Core Mass - Protons = Neutrons 40u - 20u = 20u, this means Calcium has 20 electrons, 20 protons and 20 neutrons.
Electrons have a smaller mass than both protons and neutrons. Both protons and neutrons are over 1800 times as massive as electrons.
# of protons = # of electrons # of protons/ electrons + # of neutrons = atomic mass
Mass of an atom = mass of protons + mass of neutrons
For a stable atom, no. of protons= no. of electrons no of neutrons= Atomic Mass- no. of protons
The number of protons
Americium has 95 protons and electrons. Number of neutrons: atomic mass of an isotope - number of protons
For a stable atom, no. of protons= no. of electrons no of neutrons= Atomic Mass- no. of protons
protons plus neutrons
Americium has 95 protons and electrons. Number of neutrons: Atomic Mass of an isotope - number of protons
Silicon 28 (28Si) has 14 protons, neutrons and electrons.
Because the mass of electron is negligible when compared to the mass of protons or neutrons.