Nuclear model

• Atom is a part of matter.

  Matter is any physical substance that takes up space and has mass
• The atom is a central positively charged nucleus made up of protons and neutrons surrounded by electrons held by electrostatic forces.
• 99% of mass is in the nucleus
• Protons and neutrons are called nucleons
• Elementary particles is a particle whose substructure is unknown e.g. Electrons and quarks
• An isotope is an element with the same number of protons but different number of neutrons
• Gold has the most isotopes while only 1 is stable.
• Relative atomic mass (RAM) is the average of masses of all isotopes