BIOL 1201 Chapter : Biology 1201 Chapter 2
Document Summary
Matter consists of chemical elements in pure form and in combinations: organisms are composed of matter: anything that takes up space and has mass, elements and compounds. Matter is made up of elements: a substance that cannot be broken down to other. A compound consists of two or more elements combined in a fixed ratio. Emergent properties come from element to compound: essential elements of life. About 25 of the 92 elements found in nature are essential to life. Oxygen (65%) carbon (18. 5%) hydrogen (9. 5%) nitrogen (3. 3%) Trace elements are required by organisms in only minute qualities (i. e. iron, iodine, etc. ) An element"s properties depend on the structure of its atoms: an atom is the smallest unit of matter that still retains the properties of an element. Each element has its own specific atom: subatomic particles compose atoms. Atomic nucleus contains densely packed protons and neutrons. This means that the atom"s nucleus is always positively charged.
