physics - atoms

physics - atoms

1. the nucleus of an atom is tiny compared to the whole this meaning an atom is mostly empty space

2. protons- found in the nucleus mass of 1 and have a + charge

   • neutron - found in nucleus mass of 1 and a neutral charge
   • electron- found in shell of atom mass of almost 0 and a - charge

3. atoms have no overall charge

   • because the number of protons = number of electrons

4. if a electron is lost or gained the atom becomes charged and is called a ion

5. atomic number = number of protons

   • mass number = number of protons and neutrons

6. a isotopes are atoms with the same number of protons but different number of neutrons

7. scientists used the plum pudding model because they thought the atom was a whole object and bits were the electrons this was proved wrong when they discovered radiation went straight though an atom