CHEM 1B Lecture Notes - Lecture 2: Lattice Energy, Ionic Compound, Ionic Bonding
10 Jan 2019
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Document Summary
Energy is released when cation and anions become ionic compounds. Lattice energy- energy change that occur when gaseous cations and anions are energy that is released is called lattice energy packed together one mole of ionic solid https://en. wikipedia. org/wiki/lattice_energy. Lattice energies are always exothermic and have - values. The formation of ionic bond is energetically favored. Q1 and q2= charges on 2 particles. Inter-ionic distance- distance between centers of cation/anions https://darkwing. uoregon. edu/~cashman/geo311/311pages/l4_paulingsrules. htm. Bond of ions of opposite charges= strongest when charge are large and inter- ionic distance is small. Trend- more exothermic when product of charges increase (q1 x q2), or when inter-ionic distance decrease (r) Most exothermic for ions of charge and size. Always look at the charge more than size bc charges have a larger contribution. Highest charge= largest negative exothermic lattice energy. If ionic charges are same, lattice energy depends on size. Lif= -1047, naf= -923, kf= -821, rbf= -785. Sample exercise: order of increasing negative lattice energy.
