CHEM 1101 Chapter Notes - Chapter 2: Unified Atomic Mass Unit, Transition Metal, Atomic Mass
14 Dec 2016
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There"s a li(cid:373)it to how far (cid:373)atter (cid:272)a(cid:374) (cid:271)e (cid:271)roke(cid:374) dow(cid:374: atom: smallest and simplest particle of an element. Atomic theory- set of assumptions proposed to explain chemical behavior of matter: 1. All matter is composed of atoms: 2. Atoms differ depending on the element: 3. Chemical compounds consist of atoms combined in specific ratios: 4. chemical reactions change only the way that atoms are combined in compounds. Atomic mass unit (amu)- convenient unit for describing mass of an atom. Protons and neutrons packed closely around nucleus. Atomic number (z)- number of protons in atoms of a given element: number of protons tells the element, also number of electrons in each atom. Atomic mass (a)- total number of protons and neutrons in an atom. Isotopes- atoms with identical atomic numbers but different atomic masses: due to differing numbers of neutrons. Most naturally occurring elements are a mixture of isotopes. Atomic weight- weighted average mass of an elements atoms.
