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Unformatted text preview: Midterm Study Guide 1 Chapter 2 – Atomic Structure and Interatomic Bonding • Atomic number – number of protons in an atom • Bohr atomic model – electrons are assumed to revolve around the atomic nucleus in discrete orbitals and the position of any particular electron is more or less well define in terms of its orbital • Wave mechanical model – electron is considered to exhibit both wavelike and particle like characteristics • Quantum numbers (dictate the size, shape, and spatial orientation of electron) o N n=1,2,3,…. Points to which shell the electron is in Related to the distance of an electron from the nucleus, or its position o L Signifies the subshell (s,p,d,f) Values range from 0 – (n-1), so s=0, p=1… Related to the shape of the electron subshell o M l Number of energy states for each subshell Ranges from –L to +L Relates to the orbitals. P subshell (L=1) has three orbitals, thus values of M l are -1,0,1 o M s The spin moment of each electrons Two values of either - 1 / 2 of + 1 / 2 • Pauli Exclusion Principle – principle stating that each electron state can hold no more than two electrons which must have opposite spins; no two electrons can have the same four quantum numbers • Electropositive elements – elements capable of giving up their few valence electrons to become positively charged ions Atomic Bonding in Solids • F N = F A + F R (Net Force = Force of Attraction + Force of Repulsion) • E o is the activation energy required for to separate two atoms to an infinite separation • R o is the equilibrium spacing • Materials with high bonding energy also have high melting temperatures • How much materials heat and contract upon cooling is related to the shape of its E o vs. r o curve o Deep and narrow trough, which typically occurs for materials having large bonding energies, correlates with low coefficient of thermal expansion and small dimensional alterations for changes in temperature Midterm Study Guide 2 Ionic Bonding • Metal + nonmetal element • In the process all the atoms acquire stable or inert gas configurations and their electrical charge makes them ions • Attractive bonding forces are coulombic , positive and negative ions attract each other • Attractive Energy (E A ) = -A/R, where the constant A = (Z...
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This note was uploaded on 08/25/2011 for the course MSE 27-100 taught by Professor Feinberg during the Fall '10 term at Carnegie Mellon.
- Fall '10