chem. 4 & 5

Protons

Positively charged, determine atoms identity

Neutron

Neutral particles, helps hold nucleus together

Electrons

Negatively charged, responsible for properties

J.J. Thomson

Discovered the electron in 1897 through cathode ray tube experiments

Ernest Rutherford

Discovered the atomic nucleus through gold foil experiment in 1911

What makes elements and isotopes different from each other?

By having different a number of neutrons

protons and neutrons make what?

Mass number

Isotopes

Atoms with the same number of protons but differing numbers of neutrons

Neil’s Bohr

Propose that electrons were found orbiting in specific paths around the nucleus

Energy levels

The orbital paths electrons were found in

Quantum

The amount of energy required to move an electron from one energy level to another

Electron configuration

The ways in which electrons are arranged around the nucleus of an atom

Aufbau Principal

States that electrons occupy orbitals of lowest energy first

Pauli exclusion principle

An atomic orbital may describe, at most two electrons, two electrons occupying the same orbital must spin in opposite directions.

Hunds rule

Every orbital in a sub-shell is singly occupied with one electron before any one orbital is doubly occupied.

Frequency

The number of waves that pass a given point per unit time, represented by the letter v, measured wps or hertz

Amplitude

Waves height from zero to crest

Crest

Peak of a wave

Trough

Lowest part of a wave

The photoelectric effect

The ejection of electrons when light shine on a metal

Ground state

When an electron is in its lowest energy level

Excited state

When a molecule gains extra energy, causing one of its electrons to jump to a higher, less stable energy level

Louis De Brogile

Theorized that all matter can exhibit wavelike frequencies

Heisenberg uncertainty principle

States that it is impossible to know both the position and the velocity of a particle at the same time

Democritus

Developed the first atomic theory

As wavelength increases frequency…

Decreases

As wavelength decreases frequency…

Increases