Atom: 5 Things You Should Know

Question: Ancient Greek thinkers named the atom “atomos,” meaning “uncuttable.” Why did later scientists find the name was misleading?

Answer: Atoms were once thought to be the smallest, unbreakable bits of matter. In fact, every atom is built from even tinier particles: protons, neutrons, and electrons.

Question: In 1909, scientists fired tiny particles at thin gold foil, and most went straight through. Why didn’t the gold block them?

Answer: An atom is almost entirely empty space, with nearly all its mass packed into a tiny nucleus. If an atom were the size of a stadium, the nucleus would be about the size of a marble.

Question: Alchemists spent centuries trying to turn lead into gold and always failed. What makes one element different from another?

Answer: Every element is defined by its number of protons: gold has 79, and lead has 82. Changing an element means changing its nucleus, which no ordinary chemical reaction can do.

Question: Hydrogen and oxygen are both gases, yet together they form liquid water. How do their atoms join to make a new substance?

Answer: Atoms link up by sharing or swapping electrons, which creates chemical bonds. Those bonds let a few kinds of atoms build millions of different substances.

Question: Your body contains carbon, oxygen, and iron atoms that are billions of years old. What first created most of these atoms?

Answer: Hydrogen and helium formed after the Big Bang, but heavier atoms like carbon and iron were forged inside stars. When those stars exploded, they scattered the atoms that later became planets and people.