Gr.9 Science Unit 2: Atomic Theory & Elements

Neils Bohr Atom Model

-Displays up to 20 electrons

-Atoms are NUETRAL

-Number of protons and neutrons inside nucleus of model

What did Democritus (400 BCE) discover?

Discovered the atom which make up matter

What did J.J Thompson (1897) discover?

-Electrons, using the cathode ray tube.

-Discovered negative & positive charges are attracted

-Plum Pudding model

What did John Dalton (1807) discover?

Compounds are made of different elements in fixed ratios

What did James Chadwick (1932) discover?

-Discovered the neutron

-By bombarding berylium with alpha particles

-Atom is an empty sphere with dense central nuecleaus

What did Neils Bohr (1913) do?

-Figured out the electron's orbit around the nucleus

-e's have definite energy & can jump orbitals

-Further e is from nucleus = more energy

What did Ernest Rutherford discover?

-Nucleus and protons

-By bombarding gold foil with +charged atoms

mass of an atoms is based on the number of ________ & ________.

protons and neutrons because electrons mass is close to 0

Group 17 on periodic table

Halogens (most reactive non-metals)

Group 18 on periodic table

Noble Gases: -gases at room temperature, full valence shells, very stable

Two types of scientific notation

Standard scientific notations & nuclear notation

What are isotopes?

Different version of an element with a same atomic number but different number of neutrons

A = ?

P + N

#P = ?

#E

What is the scientific method?

1. Question

2. Hypothesis

3. Experiment

4. Observe & Record

5. Analyze

6. Share results