science quiz 3

Greek philosopher who talked about atomos

Democritus

Person who proposed atomic theory

John Dalton

Discovered electrons

JJ Thomson

Discovered the nucleus of an atom

Ernest Rutherford

Discovered neutrons

James Chadwick

Charge of protons electrons neutrons

Protons positive electrons negative neutrons neutral

Charge of alpha particles

Positive two

Discovered nucleus of an atom

Ernest Rutherford

Proposed plum pudding model of atom (What is the plum pudding model)

JJ Thomson, Model of a positively charged “pudding” and with negatively charged electrons “plums”

Charge of cathode rays

Negative

Performed gold foil experiment (What is the gold foil experiment)

Ernest Rutherford, Positively charged alpha particles fired at a thin piece of gold foil, if plum pudding was correct it would’ve passed through, instead 1/8,000 bounced back proving there is a nucleus

Charge of nucleus

Positive

Proposed law of conservation of mass

Antoine Lavoisier

Proposed law of constant composition

Joseph Louis Proust

Discovered static electricity

Benjamin Franklin

Discovered electricity

Micheal Faraday

Discovered radioactivity

Henry Becquerel

Discovered radium + polonium

Marie Curie and Pierre Curie

Discovered atomic number

Henry Moseley

Discovered mass of electron

Robert Millikan

Atomic number definition

Number of protons in an atom

Mass number definition

Sum of protons and neutrons in an atom

Isotope definition

Atoms of same element with different neutron counts

Law of constant composition

Compounds always contain same element ratios by mass

Rutherford gold foil conclusion

Atom is mostly empty space with a dense positive nucleus

Discovered protons

Goldstein & Thomson

Postulates of Dalton’s atomic theory

• All matter is made of tiny, indivisible particles called atoms.

• Atoms of the same element are identical in mass, size, and chemical properties.

• Atoms of different elements have different masses and properties.

• Atoms combine in fixed, simple whole-number ratios to form chemical compounds.

• Atoms cannot be created, destroyed, or subdivided in a chemical reaction; reactions only rearrange them.