BIO 121 Lecture Notes - Lecture 2: Radiometric Dating, Atomic Nucleus, Electron Shell
Document Summary
Concept: matter consists of chemical elements in pure form and in combinations called compounds. Matter anything that takes up space and has mass. The elements of life approximately 20% - 25% of the 92 elements are essential to life essential elements carbon, hydrogen, oxygen, nitrogen make up 96% of living matter. Most of the remaining 4% consists of calcium, phosphorus, potassium, and sulfur trace elements elements required by organisms in only minute quantities: elements in the human body. Concept: an element"s properties depend on the structure of its atoms each element consists of unique atoms. Atom the smallest unit of matter that still retains the properties of an element. Atomic nucleus made up of neutrons and protons. Daltons used to measure the mass of neutrons and protons electrons form a cloud around the nucleus: neutron and proton mass are almost identical. Atomic number and atomic mass atoms of the various elements differ in number of subatomic particles.
