Chemistry Atomic Theory & The Periodic Table

atom

The smallest unit of an element that still has the properties of that element

proton

The positive subatomic particle in the nucleus of an atom

neutron

The neutral subatomic particle in the nucleus of an atom

electron

The negative subatomic particle in the electron cloud of an atom

valence electrons

Electrons in the outermost energy level of the electron cloud

quarks

Make up protons and neutrons and their attraction holds the nucleus together

Plum pudding model

the atom is positively charged with negatively charged particles embedded throughout

Nuclear model

the center of the atom (nucleus) is positive and the negative part surrounds it

Bohr model

e^- travel in fixed orbits around the nucleus

Electron cloud model

e^- are in shells in the cloud but do NOT travel in fixed orbits

atomic number

Number of protons in an atom of the element; used to identify an element

mass number

Number of protons and neutrons in the nucleus of an atom

groups

Aka families; the vertical columns on the periodic table

periods

The horizontal rows on the periodic table

isotopes

Atoms of the same element with different numbers of neutrons

average atomic mass

Weighted average of all of the different versions of an element; measured in amu

ion

a charged atom