03- Atomic structure

• structure of an atom

  proton

  • relative charge: +1
  • relative mass: 1
  • in the nucleus

  neutron

  • relative charge: neutral
  • relative mass: 1
  • in the nucleus

  electron

  • relative charge: -1
  • relative mass: 1/1840, negligable
  • around the nucleus, in the electron shell
• atomic/ proton number (Z) is the number of protons
• mass/ nucleon number (A) is the total number of protons and neutrons
• atom: smallest particle that can still have the chemical characteristics of an element, electrically neutral
• ion: particles formed when an atom or group gains or loses and electron, but the number of protons and neutrons remain the same

  cation: positive ion

  anion: negative ion
• isotopes: atoms of the same element that have the same proton number but different nucleon numbers
• electron shells:

  innermost shell - lowest energy

  outermost shell - highest energy

  outermost shell -> valence shell -> contains valence electrons

  for an atom to be electronically stable, the valence shell must be full

  electron configuration: 2.8.8