Chemistry Model 3: Discoveries in Radioactivity

Draw and label Rutherford's Model of the Atom

(Nucleus is positive, outside dots are negative)

What are the 2 ways model three differed from model 2

1.) Rutherford's model was mostly empty space 2.) Rutherford's model had a tiny dense positive nucleus

what 2 things were wrong with the new model

1.) according to physics, the negative charged electrons should be pulled into the positive nucleus 2.) the protons alone did not account for the know masses of atoms. There must be another particle in the nucleus

What 2 new things were learned about the atom as a result of the gold foil experiment

1.) an atom is mostly empty space instead of a solid sphere SINCE most of the alpha particles passed straight through 2.) an atom must have a tiny densely packed POSITIVE inner core called the nucleus SINCE 1/8000 of the positive alpha particles were repelled backward

How was radioactivity accidentally discovered?

Becquerel was studying the effect of sunlight on strange rocks that gave off energy. One day it could not be done. He knew the release of energy by the uranium sample happened without sunlight.

Who accidentally discovered radioactivity and 'about' when?

Becquerel; 1896

Who did the study that led to the discovery of the 3 forms of radioactivity?

Ernest Rutherford around 1899

Who did very important work in finding the 'source' or cause of radioactivity and discovered radioactive elements

Marie Curie attributed the release of radioactivity to changes taken place in atoms. She also discovered 2 radioactive elements and won 2 Nobel Prizes in Physics

What two scientists actually performed the Alpha Particle Scattering Experiment and when?

Marsden and Geiger: 1909-1911

As a result of the gold foil experiment a new model of the atom came out. Who came up with it?

Rutherford

what is one of the names of the third model of the atom

Rutherford's nuclear model

gamma (table) (Symbol, charge, size, energy, penetrating ability)

Symbol: Y charge: neutral size: no mass energy: high penetrating ability: best

What surprising thing happened during the Gold Foil Experiment

about 1/8000 alpha particles were deflected backwards which would be like a cannon ball bouncing off tissue paper

what is the electric force

force of attraction or repulsion between charged objects, electrons held are held by attraction of protons in the nucleus

what is the nuclear force

huge force that holds the protons and neutrons together in the nucleus

What did Moseley find out about protons

proton's determine the chemical behavior and properties of the atom

What new particle was introduced to the atom in this new model?

protons

describe this new particle: (protons)

protons are a positive particle found in the nucleus

Beta (table) (Symbol, charge, size, energy, penetrating ability)

symbol: B ^0 e -1 charge: - size: small energy: medium penetrating ability: better

Alpha (table) (Symbol, charge, size, energy, penetrating ability)

symbol: a ^4 He 2 charge: 2+ size: big energy: low penetrating ability: poor

What is radioactivity

the spontaneous release of energy in the form of particles and ray