Unit 2 Chem atomic structure, radioactivity

atomic #

number of protons

isotope

Atoms of the same element that have different numbers of neutrons

average atomic mass

the number of protons and neutrons in an atom of an element

mass number

number of protons and neutrons for an individual isotope

alpha particle

a helium nucleus emitted by some radioactive substances, originally regarded as a ray.

4/2 He

isotopic notation of an alpha particle

negative beta particle

An electron with no mass and a proton number of -1. Occurs when there's too many neutrons, so the neutron turns into a proton

0/-1 e

isotopic notation of negative beta particle

gamma radiation

electromagnetic / light radiation

transmutation

when one element turns into another

radioactive half life

the time it takes for a radioisotope to decay to half its sample size

John Dalton

This man created the first atomic theory and the law of definite proportions

JJ Thomson

This man discovered the electron and that atoms have parts. He also discovered that atoms are divisible and used a CRT to generate the plum pudding model

Rutherford

This man developed the nuclear model, discovered the nucleus and alpha particles, performed the gold foil experiment

Niels Bohr

This man discovered that electrons move around the nucleus in orbits called electron shells.