Nuclear Physics

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History

1895 (Röntgen)

Systematic study of cathode rays

Rays absorbed by different materials

X-rays

1896 (Becquerel)

U salts fluoresce when exposed to sunlight

Do they emit other types of radiation?

Placed U salt over wrapped, protected photographic plate

image of salt observed on developed plate, even when not exposed to sunlight

U salt emits invisible radiation that was not induced by sunlight

Marie Curie

U rays - theory of radioactivity

search for other radioactive substances

new elements - Po Rd

Radioactive isotope isolation techniques

died in 1934 of aplastic anaemia due to radiation exposure

First woman to win a nobel prize (1903, physics with husband and Becquerel)

First person to win 2 nobel prizes (1911 - Chemistry)

Atomic structure review

atom - smallest particle that is characteristic of an element

Nucleus of protons (p) & neutrons (n) - nearly all of the mass of the atom

Electrons (e-) orbit the nucleus and occupy shells at fixed energy

p has positive charge, equal and opposite to negative charge of e-

n has no charge, about the same mass as a p (≈ mass of a hydrogen atom)

an atom of any given element always has the same number of p - proton number or atomic number of the element, Z

The mass number of p and n is called the mass number, A

An atom of any given element may have different number of n - isotope. usually refers to isotopes by name of element followed by its mass number - e.g. Hydrogen 1, Hydrogen 2, Uranium 235, etc...