Atoms

• The ancient Greek philosopher Demokritos (460-370 BCE) thought that matter was made up of millions of tiny, uncuttable pieces of that same matter.
• what atomic model is this and who made it?

  A) plum pudding model

  B) JJ Thomson

  
• what experiment does this diagram suggest?

  A) alpha particle experiment

  
• Who discovered the nuclear atom, a small, positively-charged nucleus surrounded by empty space and then a layer of electrons to form the outside of the atom?

  Rutherford
• Who suggested that electrons orbit the nucleus in fixed shells?

  Neils Bohr
• Who discovered the neutron?

  James Chadwick
• Most alpha particles going through the gold foil tells us atoms are mostly empty space.
• What do A, Z and X stand for?

  A: mass number

  Z: atomic number

  X: symbol

  
• Atoms with different amount of neutrons but same number of protons are called isotopes.
• When an atom loses or gains electrons, this is atom is called an ion.