A negatively charged subatomic particle with a mass about 1/1836 of a proton, discovered by J.J. Thomson.
Practise Atomic Structure & Periodicity All Atomic Structure & Periodicity topics
The electron is a negatively charged subatomic particle with charge -1.602 x 10^-19 C and mass 9.109 x 10^-31 kg, about 1/1836 of a proton's mass. J.J. Thomson identified it in 1897 by measuring the deflection of cathode rays in electric and magnetic fields, which gave its charge-to-mass ratio. Electrons occupy orbitals around the nucleus, and their arrangement determines bonding, colour, conductivity and reactivity. Because electrons are light and mobile, they carry electric current in metals and move readily during chemical reactions. Their behaviour is described by quantum mechanics rather than by classical orbits.
Key ideas: The electron has charge -1.602 x 10^-19 C, mass 9.109 x 10^-31 kg (about 1/1836 of a proton), and charge to mass ratio 1.76 x 10^11 C per kg (Thomson). Its arrangement determines bonding and reactivity. Electrons are also described as waves with spin 1/2, and they are the carriers of electric current in metals.
Common mistakes and connections: Students think electrons orbit the nucleus like planets and that they are tiny balls with definite paths. Also, the electron mass is negligible in atomic mass calculations but not zero. Link this to cathode rays, quantum numbers and electron configuration.
Relative to the electron, the proton and neutron are about 1836 times heavier, so almost all of an atom's mass is in its nucleus. The interactive lesson shows this as a live animation or chart.
In a copper wire, free conduction electrons drift under an applied voltage and carry the electric current.
A negatively charged subatomic particle with a mass about 1/1836 of a proton, discovered by J.J. Thomson.
Electron is a beginner topic in Atomic Structure & Periodicity. It needs no earlier chemistry lessons and is a good starting point.
Study these earlier topics in Atomic Structure & Periodicity first: Law of Definite Proportions, Law of Multiple Proportions, Dalton's Atomic Theory.
The next topics in Atomic Structure & Periodicity are Proton and Neutron.
Yes. The interactive lesson includes a self-check question on Electron, and the Atomic Structure & Periodicity quiz draws on every topic in this area.
Electron is topic 13 of 115 in Atomic Structure & Periodicity.