Britannica Educational Publishing IN ASSOCIATION WITH ROSEN EDUCATIONAL SERVICES LET’S FIND OUT OUR DYNAMIC EARTH THE NITROGEN CYCLE BOBI MARTIN
EVERY LIVING THING NEEDS NITROGEN From tiny insects to plants and people all living things need nitrogen to survive Nitrogen is a chemical element that has no color taste or smell Scientists use symbols to stand for the names of chemical elements VOCABULARY A chemical element is a basic substance that cannot be broken down into simpler substances The gases that make up air nitrogen 78 oxygen 21 argon carbon dioxide and others 1 2011 Encyclopædia Britannica Inc Air is a mixture of several gases mostly nitrogen and
Nitrogen is found in all living things including people and animals The symbol for nitrogen is N Nitrogen is a gas that makes up about 78 percent of Earth’s atmosphere This gas form is sometimes called free nitrogen In addition free nitrogen is found in many meteorites and in some stars It is also in the gases of volcanoes mines and some mineral springs Nitrogen is one of the main chemical elements found in all living things But living things cannot use nitrogen in its gas form The nitrogen that is found in living things must first be combined with other elements Such combinations are called compounds 5
