LIFESCI 7A Study Guide - Spring 2018, Comprehensive Midterm Notes - Enzyme, Dna, Chromosome
Document Summary
Elements: a pure substance, such as oxygen, copper, gold, or sodium, that cannot be further broken down by the methods of chemistry. Atoms consist of protons, neutrons, and electrons. Nucleus (of an atom): the dense central part of an atom containing protons and neutrons. Proton: a positively charged particle in the atomic nucleus. Electron: a negatively charged particle that moves around the atomic nucleus. Atomic mass: the mass of the atom determined by the number of protons and neutrons. isotopes: atoms of the same element that have different numbers of neutrons. ion: an electrically charged atom or molecule (+ or -). Electrons occupy regions of space called orbitals. Orbital: a region in space where an electron is present most of the time. Shell: an energy level in which an orbital can exist. Note; rutherford"s gold foil experiment: atoms are made up of mostly empty space and a small, densely packed nucleus. Elements have recurring, or periodic, chemical properties.
