| What is the radius of the an Atom & a Nucleus | Atom's radius = 1 × 10^-10 m
Radius of a Nucleus =1 × 10^-14 m |
| What are the Charges and Masses of the Subatomic Particles? | View Image: |
| What is the Atomic Number? | The number of protons in an atom (this defines what element an element is) |
| What is the Mass Number? | Protons + Neutrons |
| What are isotopes? | Atoms of the same element with a different number of neutrons (same atomic no. but different mass no.) |
| What does the electron determine? | An elements chemical properties |
| Whats the relative atomic mass? | average mass of the atoms of the isotopes, calculated from:
- the mass numbers of its isotopes
- the abundance(plentifulness) of these isotopes |
| What did John Dalton do? | JOHN DALTON:
1- Published his ideas in 1803
2- All matter was made of tiny spheres that cant be divided - atoms
JJ THOMSON:
1- Nearly 100 years later, discovered electrons
2- Plum pudding model: ball of + charge, - electrons embedded
ERNEST RUTHERFORD:
1- Positive charged alpha particles fired at thin gold foil
2- most went through: mostly empty space
3- few scattered in all directions: positively charged nucleus concentrated at atoms centre
NIELS BOHR:
1- Did calculations& experiments: electrons orbit the nucleus in shells at fixed distances
FURTHER EXPERIMENTS:
1- Protons: positive charge
JAMES CHADWICK:
1- 1932, found evidence for mass in nucleus with no charge - neutrons |
