Unit 5: Atomic Structure

IPC

Atom

Smallest particle of an element which retains the properties of that element.

Proton

Subatomic particle located in the nucleus of an atom that has a positive charge.

Neutron

Subatomic particle located in the nucleus of an atom that has a neutral charge.

Electron

Subatomic particle located in the electron cloud surrounding the nucleus that has a negative charge.

Quarks

Particles that make up protons and neutrons.

Valence electrons

Electrons in the outermost energy level of the electron cloud.

Atomic number

Number of protons in an atom; identifies the element; periodic table is arranged by this number.

Mass number

Number of protons & neutrons in an atom.

Isotopes

Atoms of the same element with different numbers of neutrons.

Average atomic mass

Weighted average of all the isotopes of a particular element; number shown on periodic table; it is closest to the mass number of the most common isotope for the element.

Groups

Vertical columns on the periodic table that indicate the number of valence electrons an atom has.

Periods

Horizontal rows on the periodic table that indicate the number of energy levels an atom has in its electron cloud.