Ion — Science definition
Defined in 3 courses:
- An atom or group of atoms with net electric charge because positive and negative charges do not balance. (Physical Science: Matter, Forces & Energy)
- An atom that has gained or lost electrons, giving it a net negative or positive charge. (Physical Science: Chemistry)
- An atom (or group of atoms) that carries an electric charge because it has lost or gained electrons. (Physical Science: Chemistry)
Where it is taught
- Atomic Structure — Properties of Matter, Physical Science: Matter, Forces & Energy, Grade 8
- Atomic Models & Subatomic Particles — Atoms, Electrons & Periodicity, Physical Science: Chemistry, Grade 11
- Ionic Bonding — Bonding, Formulas & Molecular Structure, Physical Science: Chemistry, Grade 11
In use
If it gains an electron it becomes a negative ion; gaining an electron does not change its element.
Atomic Structure
When an atom gains or loses electrons it becomes an ion with a net charge, but its proton count — its identity — never changes.
Atomic Models & Subatomic Particles
In ionic compounds, ionic bonding is electrostatic attraction throughout a lattice; electron transfer helps account for ion formation but is not itself the lattice bond.
Ionic Bonding
Questions using ion
Problem 1
Answer and explanation
18
A 2− ion has gained 2 electrons: electrons = protons + 2 = 16 + 2 = 18.
Problem 2
Hints
Electrons affect ion charge; protons identify the element.
Answer and explanation
Magnesium, charge 2+; positive charges exceed negative by two.
Problem 3
Answer and explanation
Z=17, A=35, chlorine with charge −1: ³⁵Cl⁻. Changing neutron number while keeping 17 protons makes another chlorine isotope. Changing only electron number changes its ionization state.
Z=17, A=35, chlorine with charge −1: ³⁵Cl⁻. Changing neutron number while keeping 17 protons makes another chlorine isotope. Changing only electron number changes its ionization state.
Response criteria
- Use the stated measurements or conditions, with correct units.
- Connect the result to the chemical mechanism or evidence relationship.
- Identify the assumption, model limit or further evidence requested.
Problem 4
Answer and explanation
Z=17, A=35, chlorine with charge −1: ³⁵Cl⁻. Changing neutron number while keeping 17 protons makes another chlorine isotope. Changing only electron number changes its ionization state.
Z=17, A=35, chlorine with charge −1: ³⁵Cl⁻. Changing neutron number while keeping 17 protons makes another chlorine isotope. Changing only electron number changes its ionization state.
Response criteria
- Use the stated measurements or conditions, with correct units.
- Connect the result to the chemical mechanism or evidence relationship.
- Identify the assumption, model limit or further evidence requested.
Taught alongside
- atom
- proton
- neutron
- electron
- nucleus
- atomic number
- mass number
- isotope
- model
- evidence
- system boundary
- assumption
- atomic number (Z)
- mass number (A)