⚛️ Atoms and elements

An atom is the smallest piece something can be broken into while still being that same substance, a single tiny unit made of even smaller parts called protons, neutrons and electrons. Atoms are so small that a single grain of sand contains more atoms than there are grains of sand on an entire beach. Everything around you, your body, the air, this screen, is built entirely out of different combinations of atoms.

An element is a substance made of only one type of atom, like pure oxygen, pure gold, or pure carbon, and it cannot be broken down into anything simpler using ordinary chemical means. Scientists have found about a hundred and twenty different elements so far, and every single object in the universe is built by combining them in different ways. The periodic table is simply a chart that lists every known element and organises them by how they behave.

The periodic table arranges elements by how many protons their atoms have, and it groups elements with similar behaviour into the same columns, so scientists can predict how a new or unfamiliar element might act just by looking at where it sits. Elements in the same column often react in similar ways, for example all the elements in one particular column are shiny metals that react strongly with water. This clever organisation is exactly why the periodic table is considered one of science's most useful tools.

Electricity is really just electrons, tiny charged particles inside atoms, flowing in a steady stream through a material like a wire. Some materials, like copper wire, let electrons move through them easily, which is why they are used to carry electricity, while other materials hold their electrons tightly and barely let electricity pass at all. When you flip a switch, you are opening a path that lets electrons flow all the way around a circuit and back again.