Subatomic particles

• Subatomic Particles


  • Protons
  • Neutrons
  • Electrons
• Atoms are very, very small and typically have an atomic radius of about 0.1mm or 1 x 10-10m
• Subatomic Particles


  • Proton
  • Neutron
  • Electron
• Relative Mass


  • Proton: 1
  • Neutron: 1
  • Electron: very small
• Relative Charge


  • Proton: +1
  • Neutron: 0
  • Electron: -1
• Almost all of the mass of an atom is in the nucleus
• The radius of the nucleus is less than 1/10,000 of the atomic radius of the atom, so most of an atom is empty space
• Atoms have no overall charge because they contain an equal number of protons and electrons
• All atoms of a particular element have the same number of protons
• Atoms of different elements have different numbers of protons
• Atomic number


  The number of protons in an atom
• Mass number


  The sum of the protons and neutrons in an atom
• In the modern periodic table, elements are arranged in order of increasing atomic number
• Calculating number of neutrons


  Number of neutrons = mass number - atomic number