Electron — Science definition
Defined in 2 courses:
- A negatively charged particle that moves around the nucleus in an electron cloud. (Physical Science: Matter, Forces & Energy)
- A negatively charged (−1) subatomic particle occupying the space around the nucleus, with a mass roughly 1/1836 that of a proton. (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
In use
Negatively charged electrons are described by a surrounding electron cloud.
Atomic Structure
Thomson studied cathode rays and discovered a particle far lighter than any atom — the electron**.
Atomic Models & Subatomic Particles
Questions using electron
Problem 1
Hints
Check that changing neutron count leaves both proton count and charge unchanged.
Answer and explanation
Mass number=13+14=27; there are 13 electrons because neutrality requires equal positive and negative charges.
Problem 2
Answer and explanation
1
Losing a negative electron leaves one more proton than electron, giving a charge of +1.
Problem 3
Hints
State what the supplied observations or conditions establish, and separate that from any assumption.
Answer and explanation
Quantum models describe orbital probability distributions rather than definite classical trajectories; simple drawings omit that distinction.
Problem 4
Answer and explanation
Charge=17−18=−1; atomic number 17 identifies chlorine, so Cl⁻. A shell diagram is an organizing model, not a literal path for an electron.
Response criteria
- State a scientifically accurate conclusion.
- Show the calculation or mechanism that supports it.
- Include units, conditions, or limits where relevant.
Taught alongside
- atom
- proton
- neutron
- nucleus
- atomic number
- mass number
- isotope
- ion
- model
- evidence
- system boundary
- assumption
- atomic number (Z)
- mass number (A)