atoms and periodic table

• atom?

  the smallest part of an element
• structure of an atom?

  • has a nucleus in the centre - contains protons and neutrons
  • surrounded by shells of electrons
• proton mass and charge?

  mass = 1

  charge = +1
• neutron mass and charge?

  mass = 1

  charge = 0
• electron mass and charge?

  mass = 0.0005

  charge = -1
• number of protons = number of electrons
• mass number (big number) = total number of protons and neutrons in the nucleus
• atomic number (small number) = total number of protons in the nucleus
• isotopes?

  atoms of same element with same number of protons and different number of neutrons
• relative formula mass calculations?

  • use 'dead frog'
  • (mass number x percentage) of each isotope added together / 100
• group 8 gases - noble gases = have a full outer shell so do not readily react
• periodic table organised by atomic number
• a group is a vertical column of similar elements
• a period is a horizontal row of elements
• are metal oxides bases or acidic?

  basic
• non-metal oxides are acidic
• the group tells us that elements have the same number of electrons in the outer shell
• the period tells us an element has the same number of electron shells
• why do elements in the same group have similar chemical properties?

  elements have same number of outer shell electrons