Details of the three Sub-atomic (fundamental) Particles Particle Position Relative Mass Relative Charge Proton Nucleus 1 +1 Neutron Nucleus 1 0 Electron Orbitals 1/1840 -1 An atom of Lithium (Li) can be represented as follows: 7 3 Li Atomic Number Atomic Symbol Mass Number The atomic number, Z, is the number of protons in the nucleus. The mass number ,A, is the total number of protons and neutrons in the atom. Number of neutrons = A – Z Isotopes Isotopes are atoms with the same number of protons, but different numbers of neutrons. Isotopes have similar chemical properties because they have the same electronic structure. They may have slightly varying physical properties because they have different masses.
126.96.36.199 Fundamental particles
Appreciate that knowledge and understanding of atomic structure has evolved over time. Protons, neutrons and electrons: relative charge and relative mass. An atom consists of a nucleus containing protons and neutrons surrounded by electrons.
188.8.131.52 Mass number and isotopes
Mass number (A) and atomic (proton) number (Z). Students should be able to: • determine the number of fundamental particles in atoms and ions using mass number, atomic number and charge • explain the existence of isotopes.