Elements

• Main groups of elements

  • Metals (metallic properties) 98/118
  • Nonmetals (no metallic properties) 19/118
  • Metalloids (both properties) 0/118
• 98 of 118 elements occur in nature
• 20 elements were produced in a lab
• Chemical symbol

  1 or 2 letters, first is capitalised
• Copper


  Cuprum
• Iron


  Ferrum
• Potassium


  Kalium
• Lead


  Plumbum
• Gold


  Aurum
• Silver


  Argentum
• Mercury


  Hydrorgyrom
• Atomic number

  Always the smallest number
• Isotopes


  Elements with the same number of protons but a different number of neutrons
• Relative atomic mass (Ar or RAM)


  An average atomic mass value based on the abundance of each isotope
• Calculating relative atomic mass

  1. Multiply masses by abundance

  2. Add them together

  3. Divide by 100
• Relative atomic mass (RAM) is the average mass value based on the abundance of each isotope. The atomic number of silver is 47.
• Helium has an atomic mass of four because its nucleus consists of two neutrons and two protons.
• Pure substances are made of one type of atom. This is also known as a homogeneous material.