Atoms, elements and chemical symbols
The alphabet of matterThe alphabet of matter
Twenty-six letters spell every word in English. About 118 elements build every kind of matter in the universe, from your sneakers to the stars.
• An atom is like a single letter: the smallest piece of an element.
• An element is like one letter of the alphabet: every atom in it is the same kind.
• A chemical symbol is the element's short name on the periodic table.
Worked example: what elements do the symbols O, Na and Fe stand for?
Step 1: A chemical symbol is one or two letters. The first letter is always a capital, and a second letter is always lowercase.
Step 2: Find O on the periodic table: it is oxygen. Many symbols come from the element's English name, like H for hydrogen and C for carbon.
Step 3: Na is sodium and Fe is iron. Their symbols come from old Latin names: natrium for sodium and ferrum for iron.
Step 4: The number on each tile is the atomic number. It gives each element its own place in order on the table.
Every element has exactly one symbol, and every symbol means exactly one element.
Key words
- Atom: the smallest piece of an element that is still that element.
- Element: a pure substance made of only one kind of atom, like gold or oxygen.
- Chemical symbol: the one or two letters that stand for an element, like O or Na.
- Periodic table: the chart that lists every element in order by atomic number.
Big mistake to avoid
Ignoring capital letters. Co, with a lowercase o, is cobalt, one element. CO, with two capitals, is carbon monoxide: a carbon atom joined to an oxygen atom. A capital letter always starts a new element.
Cool science secret
Only about 90 of the elements are found in nature. The rest were made by scientists in labs, and some of them last less than a second before breaking apart.
Try it yourself
Use a periodic table to name these elements: He, Ca and K.
Answers: helium, calcium and potassium (from its Latin name, kalium).