atomic structure and perodic table

• what is an isotope ?

  different forms of the same element that have the same number of protons but different number of neutrons
• what is a molecules ?

  2 or more atoms held together by chemical bonds
• what are compounds ?

  2 or more different elements held by chemical bonds
• what are mixtures ?

  two or more substances that are not chemically combined together
• who described atoms as ' solid spheres and different spheres make up different elements '

  john Dalton
• who came up with the plum pudding model ?

  JJ Thompson
• why did JJ Thompson say 'atoms weren't solid spheres ' ?

  his measurements of charge and mass showed negatively charged particles - electrons
• how did Ernest Rutherford conduct his experiment ?

  fired alpha particles at a thin sheet of gold
• what did Bohr nuclear model suggest ?

  that all electrons were contained within a shell
• electrons orbit the nucleus in fixed shells
• what are some features of metals ?

  -metallic

  bonds

  -malleable ( able to be hammered into shape without breaking )

  -conducts electricity

  -high melting /boiling point
• what are some features of non metals ? 


  -dull

  -brittle

  -low melting / boiling point
• what are group 1 metals called ?


  alkali metals
• features of alkali metals ( group 1 metals )


  -soft

  -low density

  -low melting point
• what happens to the reactivity of group 1 metals 


  as you go down the reactivity increases
• what are group 7 called ?


  halogens
• what are some feature of the group 7 elements ?


  -melting point and boiling point

  -reactivity decreases
• what are group 0 called 


  Nobel gases