Atomic Particles ParticleChargeMass (kg)Location Electron9.109 x 10 -31 Electron cloud Proton+11.673 x 10 -27 Nucleus Neutron01.675 x 10 -27 Nucleus
Atomic Number Atomic number (Z) of an element is the number of protons in the nucleus of each atom of that element. Identifies the element Element# of protonsAtomic # (Z) Carbon66 Phosphorus15 Gold79
Isotopes Isotopes are atoms of the same element having different masses due to varying numbers of neutrons. IsotopeProtonsElectronsNeutronsNucleus Hydrogen–1 (protium) 110 Hydrogen-2 (deuterium) 111 Hydrogen-3 (tritium) 112
Mass Number Mass number is the number of protons and neutrons in the nucleus of an isotope. Mass # = p + + n 0 Isotopep+p+ n0n0 e-e- Mass # Oxygen -10 -3342 - 3115 8818 Arsenic753375 Phosphorus153116
Calculating Average Atomic Mass expressed in atomic mass units (amu) –done because actual masses so small and hard to work with –based on carbon-12 assigned mass of exactly 12 amu weighted average of all naturally occurring isotopes.
change % abundances to decimals for each isotope Multiply abundance by atomic mass of isotope Add products to get average atomic mass for element Example Chlorine has two isotopes. The isotope with a mass of 34.969 amu has a relative abundance of 75.77%. The isotope with a mass of 36.966 amu has a relative abundance of24.33%. Calculate the atomic mass of chlorine. x 34.969 = 26.49 amu x 36.966 = 8.994 amufor 24.33% = 0.2433 for 75.77% = 0.7577 for Clatomic mass = 35.484 = 35.48 amu