Atoms- the base unit of any element, smallest piece of an element that still has the qualities of the element

Electrons- negatively charged particle that orbits the nucleus of an atom

Protons- positively charged particle located in the nucleus of an atom

Ions- charged atoms

Cations- positively charged atoms/ions

• lost electrons (more protons than electrons meaning more positive charges)

Anions- negatively charged atoms/ions

• gained electrons (more electrons than protons meaning more negative charges)

Atoms can lose/gain electrons only in chemical reactions when it steals an electron from/an electron is stolen by another atom/ion

Neutrons- have a neutral charge and make up the nucleus with the protons

• all elements have neutrons except hydrogen since it only has one proton

• elements can vary in amounts of protons

• amount of neutrons effects the atoms atomic mass

Mass number: the amount of protons + neutrons in an atom

Isotopes: atoms of the same element that have different numbers of neutrons

• each has different atomic mass depending on the amount of neutrons

• does not affect how the element chemically reacts

Atomic mass: how much stuff in the atom measured in amu

• weighted average of the atomic mass of each isotope of that element

To find average atomic mass:

• relative atomic mass of 1 isotope x percent abundance = weighted score

do this for each isotope, then add the weighted scores to get the atomic mass

Example:

How to write isotopes:

element name - mass number

Element symbol:

• mass number

• atomic number

• element symbol

Carbon- 14 symbol: