Atoms and molecules

• Atom


  The smallest particle of an element
• Molecule


  A cluster of non-metal atoms that are chemically bonded together
• Molecules


  • The atoms in a molecule are joined by covalent bonds
  • Molecules have a specific formula, eg H2O or N2
• Types of molecules


  • Molecules of compounds (eg CH4)
  • Molecules of elements (eg O2)
• Ion


  An electrically charged particle, formed when an atom or a molecule loses or gains electrons
• Positively charged ion


  Formed when an atom or molecule loses an electron/electrons
• Negatively charged ion


  Formed when an atom or molecule gains an electron/electrons
• Charge on an ion


  Equal to the number of electrons lost or gained