2.5. Elements http://www.ck12.org
2.5 Elements
- Define element.
- Describe how properties of different elements compare.
- Outline the history of elements.
- Relate atoms to elements.
As this mountain of trash suggests, there are many different kinds of matter. In fact, there are millions of different
kinds of matter in the universe. Yet all kinds of matter actually consist of relatively few pure substances.
Pure Substances
A pure substance is called anelement. An element is a pure substance because it cannot be separated into any other
substances. Currently, 92 different elements are known to exist in nature, although additional elements have been
formed in labs. All matter consists of one or more of these elements. Some elements are very common; others are
relatively rare. The most common element in the universe is hydrogen, which is part of Earth’s atmosphere and a
component of water. The most common element in Earth’s atmosphere is nitrogen, and the most common element
in Earth’s crust is oxygen. Several other elements are described in the musical video at this URL:
http://www.youtube.com/watch?v=d0zION8xjbM (3:47)
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/5064