BIOL 1406 Lecture Notes - Lecture 2: Electronegativity, Covalent Bond, Ionic Bonding
Document Summary
Living organisms are subject to basic laws of physics and chemistry. O(cid:374)e e(cid:454)a(cid:373)ple is the use of for(cid:373)i(cid:272) a(cid:272)id (cid:271)(cid:455) a(cid:374)ts to (cid:373)ai(cid:374)tai(cid:374) (cid:862)de(cid:448)il"s garde(cid:374)s,(cid:863) sta(cid:374)ds of duroia trees. Organisms are composed of matter anything that takes up space and has mass. An element is a substance that cannot be broken down to other substances by chemical reactions. A compound is a substance consisting of two or more elements in a fixed ratio. A compound has characteristics different from those of its elements. About 25 of the 92 elements are essential to life. Only a few are found in large quantities. Carbon, hydrogen, oxygen, and nitrogen make up 96% of living matter. Most of the remaining 4% consists of calcium, phosphorus, potassium, and sulfur. Trace elements are those required by an organism in minute quantities. Each element consists of unique atoms the smallest unit of matter that still retains the properties of an element.
