material science chapter 2

atomic weight

average (weighted) of the atomic masses of an atom's naturally occurring isotopes.

atomic mass unit (amu)

unit for indicating atomic weight

=1/12 mass of 12C

Mole

unit for indicating atomic weight

= 6.022 x 10^23 (Avogadro’s number) atoms/mol

Quantum mechanics

set of principles and laws that govern systems of atomic and subatomic entities

Bohr atomic model

- electrons are assumed to

revolve around the atomic

nucleus in discrete orbital

- electron orbits were at a

fixed distance from the

nucleus and had a definite

energy

Wave mechanical model

- Electrons have wavelike and particulate properties.

- This means that electrons are in orbitals defined by a probability.

- Each orbital at discrete energy level is determined by quantum numbers.