1)  Make the following problems:

 a)An atom has 19 protons;

What is the atomic number?

* 19

What is the symbol?

*Potassium- K

b)If the atomic mass is 65 and the atomic number 30

How many neutrons does the atom have ?

*35

c)If an atom has 68 neutrons and the atomic mass is 118

How many electrons does the atom have?

*50

2)Draw pauli triangle and make the electronic configuration.

A) hydrogen-Z- 1

*1s^2     period: 1  group: IA number of levels: 1

B)carbon-z-6

*1s^2,2s^2,2p^2   period:2   group:IVA  number of levels: 2

C)oxygen-z-8

*1s^2,2s^2,2p^4   period:2  group:VIA    number of levels:2

D)sodium-z-11

*1s^2,2s^2,2p^6,3s^1  period:3   gorup:IA  number of levels:3

E)chlorine-z-17

*1s^2,2s^2,2p^6,3s^2,3p^5  period:3    group:VIIA number of levels:3

3)Using daltons,thomsons,rutherfords,bohrs models explain the evolution of the atom.

        Atoms were discovered trhough time with the help of each scientist.Dalton stated that all matter is made up of atoms, he believed atoms were distingushed by their mass.J.JTomson discovered small particles inside the atom he noticed they were negatively charged, he called them electrons.Ernest Rutherford made an experiment with gold foild , this experiment was held to determine the charge of the subatomic particles, he discovered a particle with possitive charge, he called it proton.Chadwick using a similar experiment to rutherfords but with berylium instead of gold foil , he ended up discovering neutrons.Lately bohr discovered the energy levels and the nucleous of the atom.And lastly heisenberg demonstrated that both the motion and the exact position of an electron can never be known precisely at the same time.He proposed that electrons are found in regions called orbitals.

4)Draw the structure of an oxygen atom.

*