Chapter 4: The Structure of the Atom

Dalton's atomic theory

states that all matter is composed of atoms

calculating % abundance of each isotope

A(x) + B(1-x) = atomic mass

gold foil experiment

Rutherford shot alpha particles at an atom, expecting none of them to be deflected. However, a few rebounded almost directly backwards.

Democritus (billiard ball theory)

atoms are the smallest building blocks in the universe

Rutherford (classical solar system)

atoms have a positively charged nucleus around which electrons orbited

isotopes

atoms with the same number of protons but different numbers of neutrons

Shrödinger model

electrons can be found in various orbitals; model describes the probability of finding an electron in any one orbital

Bohr model

electrons orbit nucleus in clearly defined energy levels

Thomson (plum pudding)

electrons were negatively charged particles scattered throughout a cloud of positive charge

atomic mass unit

equal to 1/12 the mass of a carbon-12 atom

gamma ray

high-energy radiation that has no charge and no mass

de Broglie (wave-particle model)

particles (electrons, protons, etc.) have properties of both waves and particles

radioactive decay

process (not requiring energy) by which unstable nuclei lose energy

radioactivity

process whereby some substances spontaneously emit radiation

alpha radiation

radiation deflected towards the negatively charged plate; has a charge of 2+

beta radiation

radiation deflected towards the positively charged plate

cathode ray

ray of radiation traveling from the cathode to the anode

nuclear reaction

reaction involving change in atom's nucleus

nuclear equation

shows atomic number and mass number

nucleus

the center-most part of an atom where the protons and neutrons are contained

radiation

the rays and particles emitted by radioactive material

atom

the smallest particle of an element that retains the properties of that element

atomic mass

the weighted average mass of an element's isotopes

symbolic notation

upper left - mass number; lower left - atomic number

relationship between % abundance of two isotopes

x + y = 1