Elements and Atoms For many centuries, biology was the study of the natural world. Biologists searched for unidentified plants and animals, classified them, and studied their anatomy and how they acted in nature. Then in the 1700s, scientists discovered the chemical and physical basis of living things. They soon realized that the chemical organization of all living things is remarkably similar. All living things on earth are composed of fundamental building blocks of matter called elements . More than 100 elements are known to exist, including those that are man-made. An element is a substance that cannot be chemically decomposed. Oxygen, iron, calcium, sodium, hydrogen, carbon, and nitrogen are examples of elements. Each element is composed of one particular kind of atom. An atom is the smallest part of an element that can enter into combinations with atoms of other elements.
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This note was uploaded on 11/11/2011 for the course BIO 101 taught by Professor Pesthy during the Fall '07 term at Texas State.