Basic Chemistry/Atoms and elements
Elements and the Periodic Table
Elements contain only one type of atom. They can't be split up into anything simpler. Everything on Earth is made up of elements. There are about 118 different elements, and they are listed in the Periodic Table. Every element has a name and a symbol, for example Carbon, C.
The elements are specifically arranged in the periodic table so that
- every column contains elements with similar properties. Columns are called groups.
- every row shows a gradual change or "trend" in properties across it. Rows are called periods.
- elements are listed by atomic number. (see below)
The atoms in an element are all identical. All materials are made up of atoms.
Atoms have a nucleus in the middle which is made up of protons and neutrons. Protons are positively charged whereas neutrons are neutral. Electrons spin quickly around the nucleus. They are negatively charged.