Unit 1 - Structure Of the Atom

Atom

Smallest particle of an element

Atomic Number

the number of protons in the nucleus of an atom

Nucleus

center of an atom made of protons and neutrons

Atomic Mass

the number of protons and neutrons in an atom

Isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

Ion

An atom or group of atoms that has a positive or negative charge.

Electron

a negatively charged subatomic particle

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Energy Level/ Electron Cloud

the region surrounding an atom's nucleus where one or more electrons are most likely to be found

Mass Number

the total number of protons and neutrons in the nucleus of an atom

Electron Dot Diagram

a model that represents valence electrons in an atom as dots around the element's chemical symbol

Valence Electron

an electron that is found in the outermost shell of an atom and that determines the atom's chemical properties

Metalloids

elements with properties that fall between those of metals and nonmetals

Metals

Elements that are good conductors of electric current and heat.

Nonmetals

Elements that are poor conductors of heat and electric current

The Periodic Table is organized by

atomic number (number of protons)