Atomic number

The number of protons in an atom’s nucleus

Mass number

The number of protons and neutrons in an atom’s nucleus

Atom

An electrically neutral particle because it has an equal number of protons and electrons

Ion

An atom that has become charged positively or negatively because it has gained or lost electrons

Neutral atom

An atom with an equal number of protons and electrons

Ion charge

The charge an atom has after gaining or losing electrons

Cation

A positively charged ion that has lost electrons

Anion

A negatively charged ion that has gained electrons

Cations

Positively charged ions that tend to be metals

Anions

Negatively charged ions that tend to be non-metals

Sodium ion

Na+; a sodium atom that has lost one electron and has a 1+ charge

Fluoride ion

F-; a fluorine atom that has gained one electron and has a 1- charge

Ionic charge

The net positive or negative charge of an ion

Electron loss

When an atom loses electrons, it becomes a positively charged cation

Electron gain

When an atom gains electrons, it becomes a negatively charged anion

Noble gases

Elements in group 18 that are stable because their outer orbits are full

Stable ion

An ion with a full outer orbit

Ion symbol

A chemical symbol with a superscript showing the ion’s charge

Calcium ion

Ca2+; a calcium atom that has lost two electrons

Aluminum ion

Al3+; an aluminum atom that has lost three electrons

Sulfide ion

S2-; a sulfur atom that has gained two electrons

Proton

A positively charged particle found in an atom’s nucleus

Neutron

A particle found in an atom’s nucleus that contributes to the mass number

Electron

A negatively charged particle surrounding the nucleus

Lithium atom

An atom with 3 protons, 4 neutrons, and 3 electrons in the example from the lesson

Cation naming

Cations use the same name as the atom, such as lithium ion, sodium ion, and potassium ion

Anion naming

Anion names are formed by adding -ide to the stem of the element name

Oxide ion

The negative ion name formed from oxygen

Fluoride ion

The negative ion name formed from fluorine

Sulfide ion

The negative ion name formed from sulfur

Chloride ion

The negative ion name formed from chlorine

Multivalent element

An element whose atoms can form more than one type of ion

Roman numeral

A numeral in the name of a multivalent ion that indicates its ionic charge

Iron (II) ion

Fe2+

Iron (III) ion

Fe3+

Copper ions

Copper can form ions with either a 1+ charge or a 2+ charge

Calcium ion naming

Calcium forms only one type of ion, so the ion has the same name as the element

Outer orbit

The outer electron orbit; a full outer orbit makes an atom or ion stable

Atomic number of lithium

Lithium has an atomic number of 3 because it has 3 protons

Sodium electron change

Sodium atoms lose one electron when they react with other atoms

Fluorine electron change

Fluorine atoms gain one electron when they react with other atoms

Aluminum electron change

Aluminum atoms lose three electrons when they react with other atoms

Sulfur electron change

Sulfur atoms gain two electrons when they react with other atoms

Mass number calculation

The mass number is found by adding the number of protons and neutrons

Ion charge calculation

The net charge depends on the number of positive protons compared with negative electrons