electron
Name: Electron
Details:
The electron was discovered by British physicist [discovered by]J.J. Thomson*.Electrons are the lightest charged particles in existence. Their charge is negative. They group in clouds around the nucleus of an atom. They are stable because they cannot decay into smaller components.
They have four properties: charge, mass, spin and the alignment which they assume in a magnetic field. The nucleus of the lightest atom, hydrogen, is 1,836 times more massive than an electron.
The number and arrangement of electrons around a nucleus determine the atom’s properties. The electrons are situated at one of seven different energy levels around the atom. Each shell can only hold so many electrons (shell 1= 2; shell 2 = 8; shell 3 and above = 8). When a shell is full, any other electrons are found at higher levels.
Chemical properties of atoms depend on the number of electrons in the outer shell. If it is full, the atom does not exchange electrons with other atoms, and cannot change. If the outer shell is not full, the atom can take electrons from other atoms. This is the process by which atoms form molecules.
Astrophysicists believe that electrons emerged twenty minutes after theBig Bang, but no charges were possible because extreme temperatures made stable charges impossible; when plasma began to cool to the point where stability was possible, over 380,000 years (Big History p19), then photons (light became possible).
Since the electron is so small, shining light onto it (to examine it) alters its charge and in this way, the position and movement of an electron can never be calculated at the same time. This discovery gave rise to the [made possible] Uncertainty Principle*, whose ramifications are that in examining the universe, we alter it, and so can never see the universe as it might be if unexamined.
Oneliner: The electron lighten charged particle.
Bibliography:
- Encyclopedia Britannica.
- How Stuff Works, http://www. how stuff works.com.