Chapter 2 - The Structure of The Atom and The Periodic Table

Atom

the basic structural unit of an element

Nucleus

small, dense, positively charged region in the center of the atom containing prontons and neutrons

Protons

positively charged particles

Neutrons

uncharged particles

Electrons

negatively charged particles located outside the nucleus of an atom

Atomic Number

the number of protons in the atom

Mass Number

the sum of the number of protons and neutrons

Isotopes

atoms of the same element having different masses

Atomic Mass

the weighted average of the masses of all the isotopes

Rutherford's Atom

tiny, dense, positively charged nucleus of protons surrounded by electrons

Spectroscopy

study of information obtained from absorption or emission of light by atoms

electromagnetic radiation

- travels in waves from a source
- speed of 3.0 x 10^8 m/s

Emission Spectrum

light emitted when a substance is excited by an energy source

Quantization

electrons exist in fixed energy levels surrounding the nucleus

Excited State

promotion of electrons occurs as it absorbs energy

Relaxation

energy is released as the electron travels back to lower levels