Discovering Atoms early in life

Wednesday, June 28, 2017

Sub-atomic Particles

Atoms are made of smaller particles, called protons, electrons and neutrons.  Protons are positively charged and electrons are negatively charged.  Neutral, like the name suggests, are neutral, or carry no charge at all.  This video shows how scientists discovered protons, electrons and neutrons, and why their electric charges are important to how atoms are made.

Sub-atomic particlesThe negatively charged particles were called electrons.The positively charged particles were called protons.The neutral particles were called neutrons.

The man who discovered atoms experimentally in 1802, John Dalton, thought that they were tiny solid spheres like billiard balls, and that they were the smallest particles in the universe.But in 1896, a French scientist, Henri Becquerel, discovered even smaller positively charged particles shooting out of uranium atoms.   Then in 1897, another scientist, J.J. Thompson, was able to "pull" yet smaller negatively charged particles from atoms in a metal plate connected to a high voltage inside a glass tube.   They were named "electrons".   A plasma ball shakes electrons from a gas inside the globe.  The electrons move through the gas and escape to the outside of the globe.  If you hold a normal fluorescent bulb just outside the globe, the electrons will collide with the white fluorescent coating inside the bulb and make it glow.  You are "seeing electrons".Later again in 1932, James Chadwick discovered a third particle inside atoms that carried no charge.    Scientists soon realized that atoms had even smaller particles, called sub-atomic particles, inside them.