chemistry 103 ch 8, 9, 11

chemistry 103 ch 8, 9, 11 - Chapter 8 Structure-the way...

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Chapter 8 Structure-the way atoms are arranged in space Bonding-the forces that hold adjacent atoms together 8.1 Chemical Bond Formation Chemical bond is the reorganizing of valence electrons so that a net attractive force occurs between atoms. Ionic Bond-forms when one or more valence electrons is transferred from one atom to another, creating positive and negative ions. Covalent Bond-involves sharing of valence electrons between atoms 8.2 Covalent Bonding and Lewis Structures Examples: O2, N2, H2O, CO2, CH4, polyatomic ions, and most compounds in your body COVALENT BONDS ARE COMPOSED OF ONLY NONMETAL ATOMS! IONIC COMPOUNDS ARE COMPOSED OF METAL + NONMETAL ATOMS! - Valence Electrons and Lewis Symbols for Atoms Core electrons are not involved in bonding or in chemical reactions. Chemical reactions result in the loss, gain, or rearrangement of valence electrons. For main group elements, the number of valence electrons is equal to the group number. Similar chemical properties are due to the fact that periodic groups have the same number of valence electrons. Valence electrons for transition metals are the electrons in the ns and (n-1)d orbitals. Lewis electron dot symbols-the elements symbol represents the atomic nucleus together with the core electrons and up to four valence electrons, represented by dots, are placed one at a time around the symbol; then, if any valence electrons remain, they are paired with ones already there. An octet of electrons surrounding an atom is regarded as a stable configuration (except for hydrogen which needs 2 electrons to match the configuration of helium). - Lewis Electron Dot Structures and the Octet Rule Covalent bonding is when a bond results when one or more electron pairs are shared between two atoms (can be represented by dots or a line). The bond representation is called a Lewis Structure when done in that fashion. Bond pair-the electron pair that is shared. Lone pair, or nonbonding electrons-not involved in bonding. Each molecule that is formed has a share in four pairs of electron (2 electrons only for hydrogen) so each has achieved a noble gas configuration. Each atom is surrounded by an octet of eight electrons. Octet Rule-the tendency of molecules and polyatomic ions to have structures in which 8 electrons surround each atom.
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- Drawing Lewis Electron Dot Structures Constructing Lewis structures: 1. Determine the arrangement of atoms within a molecule (central atom is usually the one with the lowest electron affinity (often C, N, P, S) (halogens are often terminal atoms except when combined with O)). 2. Determine the total number of valence electrons in the molecule or ion (in neutral atom this is the sum of valence electrons for each atom) (for anion add the number of electrons equal to the negative charge) (for cation subtract the number of electrons equal to the positive charge). 3.
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This note was uploaded on 02/25/2012 for the course CHEM 2142 taught by Professor Roberts during the Fall '10 term at Texas State.

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chemistry 103 ch 8, 9, 11 - Chapter 8 Structure-the way...

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