atomic str topic 4

• Atom


  Basic structure
• Atom


  • Radius around 1 * 10 ^ of - 10 m
  • Contains a central region called the nucleus
  • Radius of the nucleus is less than 1,000th the radius of the atom
  • Almost all of the mass of the atom is concentrated in the nucleus
• Nucleus


  Contains protons (positive charge) and neutrons (no charge)
• Electrons


  • Surround the nucleus
  • Have a negative charge
  • Found in energy levels at different distances from the nucleus
• Energy levels further from the nucleus

  At a higher energy
• Electron arrangement changes


  1. Absorb electromagnetic radiation (e.g. light) - electron moves to higher energy level

  2. Emit electromagnetic radiation - electron returns to lower energy level