BSC 114 Chapter Notes - Chapter 2: Valence Electron, Ammonium Chloride, Periodic Table
13 Sep 2016
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Document Summary
Organisms are composed of matter- anything that takes up space and has mass: matter is made up of elements- substances that cannot be broken down to other substances by chemical reactions. About 20%-25% of these are essential to living organisms. Oxygen, carbon, hydrogen, and nitrogen make up 96% of living matter. Calcium, phosphorus, potassium, and sulfur are some of the elements that compose the additional 4% Trace elements are required by an organism but only in very small quantities. Iron) are required for all life forms, others are only required by certain species (ex. Some of these naturally occurring elements are toxic to human life. Elements are composed of specific atoms- the smallest unit of matter that still retains the properties of an element. Atoms use the same abbreviations as elements, as they are just the small particles that make up elements. Atoms are composed of smaller parts known as subatomic particles.
