LIFE 102 Lecture Notes - Lecture 2: Alkaloid, Electronegativity, Ion
Document Summary
About 20-25% of the 92 elements are essential to life. *carbon, hydrogen, nitrogen, and oxygen make up 96% of living matter. The other 4% is calcium, phosphorous, potassium, and sulfur. Neutron mass and proton mass are almost identical and are measured in daltons. Two atoms of an element that differ in number of neutrons. All atoms of an element have the same number of protons but may differ in number of neutrons. Chemical behavior of an atom is mostly determined by the valence electrons. Elements with a full valence shell are chemically inert. The sharing of a pair of valence electrons by two atoms. The shared electrons count as part of each atom"s valence shell. Two or more atoms held together by covalent bonds. An atom"s attraction for the electrons in a covalent bond. The more electronegative an atom, the more strongly it pulls shared electrons toward itself. Atoms sometimes strip electrons from their bonding partners.
