CHEM 001 Class 6 Class Notes January 28, 2008 C. Cecil Cuppett, Ph.D. Chapter 3: 1. Electrons are very small particles that have a negative electrical charge. It takes about 2000 electrons to weigh as much as a proton. Electrons are abbreviated as e, -e, or –1e. Each electron is has 1 negative charge. Electrons are always on the outside surface of an atom. 2. Protons have a mass of about 1.67 x 10-24 g and have a +1 electrical charge. Neutrons weigh about the same as a proton and have no electrical charge. The protons and neutrons comprise the nucleus. Essentially, all the mass of an atom is due to the nucleus. 3. The number of protons determines what an element will be. Every element has a different number of protons and the atomic number of an element is the same as the number of protons in the element. Look at the periodic chart- the large whole numbers are the atomic numbers of the elements. On Earth, only elements up to 92, uranium, occur. 4.
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