BIOL 1201 Lecture : Lecture 3 Fall 2012
Document Summary
Readings: pgs 30-43 in campbell biology 9th edition. Atomic and molecular structure - view "pre-lecture 3 - atomic structure" before class (you are responsible for definitions used in this presentation) ** atoms only always have the same number of protons; number of electrons can vary as can neutrons. Atomic number- number of protons in an element (subscript bottom left) Mass number- number of protons+number of neutrons (superscript top left) Atomic mass- approx of total mass of an atom, measured in daltons. Isotopes different atomic forms of the same element (same # of protons, different #of neutrons) Same atomic number (number of protons and electrons), different mass number (number of protons+number of neutrons) Changes in neutron number alter the mass of the atom, but not its chemical behavior or reactivity. Radioactive isotopes an isotope in which the nucleus decays spontaneously, giving off particles and energy.
