Everything we can see and touch, and quite a lot that we can’t as well, is made of tiny particles called atoms. Some substances, like particles of this iron, contain only one kind of atom.

Humans are made of many chemical elements that work together to create ... elements needed in very small quantities. For example, iron is necessary for producing haemoglobin, a protein found ...

All organisms on Earth ride upon a "ferrous wheel" made of different forms of iron that are essential for life. Aa Aa Aa Biogeochemical cycles describe pathways by which chemical elements move ...