Dalton vs Rutherford vs Thompson

Who was John Dalton

Scientist who discovered the atomic theory

5 atomic rules

1) Atoms cannot be created or destroyed

2) Elements are made up of atoms

3) Elements are made up of the same atoms

4) Different atoms create different elements

5) Certain atoms can combine

Law of conservation of mass

Matter cannot be created or destroyed

EX:

CH₄ + 2O₂ → CO₂ + 2H₂O

If the left side started with 80 grams, the right side will end with 80 grams

Law of Constant Composition

Compounds always have the same elements in the same mass ratio.

EX: H₂O always has two hydrogens and one oxygen, and will always be proportional in mass (hydrogen to water is 1:8 no matter the type of water)

Law of multiple proportions

The same elements can make different compounds, but the mass ratios are simple whole numbers

EX: H₂O has 2 hydrogen atoms and 1 oxygen atom

and H₂O₂ has 2 hydrogen and oxygen atoms

Same atoms but different numbers and proportions.

cathode ray tube experiment

Glass tube filled with little air

• Two metal sides (cathode=negative and anode=positive) on each side of glass tube

• When battery is switched on, invisible ray is shot from the cathode to the anode

• The cathode ray was made up of small negative charged particles (electrons) as they went to the positive side (anode)

RESULT: HE DISCOVERED ELECTRONS

Who discovered the electron and how

JJ Thompson- cathode ray tube experiment

Gold foil experiment

led to the discovery of the nucleus (positive charged). alpha particles (positive) were reflected off of gold paper (positive charged b/c of nucleus). if the gold atoms were negatively charged, they would go through.

• nucleus=positive

• atoms=mostly open space

Who discovered the postive nucleus

Rutherford

What experiment proved the nucleus is positve charged?

Gold foil experiment

Protons

Positive charged

amu: 1.007

Neutron

Neutral charged (for stability)

amu: 1.008 (slightly greater than proton)

How to calculate atomic mass

neutrons + protons

What does Z represent?

proton #

What are isotopes?

An atom with the same amount of protons but a different amount of neutrons

Sulfuric acid

H₂SO₄

Nitric acid

HNO₃

Hydrochloric acid

HCl