The periodic table of the elements with the most common elements within living cells highlighted.
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L.Gardiner/Windows to the Universe

The Elements of Life

Elements make up everything around us including the trees of a forest, your pets, and even YOU!

If you looked at living things with a microscope, you would see that all life is made up of small compartments called cells. Very small life forms, such as bacteria, have only one cell, while large animals have millions. No matter what type of life form, the cells of every creature are made of atoms of different elements.

The most common elements in a cell are:
Hydrogen (H) 59%
Oxygen (O) 24%
Carbon (C) 11%
Nitrogen (N) 4%
Others such as phosphorus (P) and sulphur (S) 2% combined

But these are not the only elements that have important roles for living things! Plants and animals need a variety of elements to survive and grow.

Elements that are important for animals (including people) include calcium (Ca), for growing bones and contracting muscles, chlorine (Cl), for digesting food, fluorine (F), which is often put in drinking water to help us keep and grow our tooth enamel. Iron (Fe) is very important for animals because it helps blood cells carry essential oxygen around to all the parts of the body.

Plants also need certain elements to survive and grow including magnesium (Mg), which is a part of the chlorophyll that allows plants to convert the Sunís energy into food through photosynthesis. The elements chlorine (Cl) helps plants do photosynthesis. Some plants, such as grass, contain silica (Si), which makes them very tough and difficult for animals to munch.

Last modified July 7, 2004 by Lisa Gardiner.

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