Structure of the Nuclear Atom

Atoms aren't the smallest particles after all! Scientists discovered they can be broken down into even smaller subatomic particles. In 1897, English physicist J.J. Thomson identified electrons—negatively charged particles that are extremely light (it takes about 1,800 electrons to equal the mass of one proton).

The atom's center, or nucleus, contains positively charged protons discovered by Eugen Goldstein. Later, James Chadwick confirmed the existence of neutrons, which have no electrical charge but similar mass to protons. These particles are even made of smaller components called quarks!

Early atomic models evolved dramatically with new discoveries. Thomson first proposed the "plum pudding model" with electrons embedded in a positive sphere. This was later disproven by Ernest Rutherford's famous gold foil experiment, where alpha particles shot at gold mostly passed through but occasionally bounced back, proving that atoms are mostly empty space with a dense nucleus.

💡 Fun Fact: Robert Millikan calculated the precise charge of electrons using an ingenious experiment with oil droplets suspended between charged plates, measuring how voltage changes affected their movement.