Before class on Nov. 28, please watch the following videos. I did not make these videos, but I think the instructor uses computer animation and analogies in a way that is very helpful. There are 6 videos, and each video is 4 minutes or less, so you have in total between 22 and 24 minutes of videos.
These videos define lattice energy as the energy required to break apart an ionic formula into separate, infinitely spaced gaseous ions. WE are defining lattice energy in the OPPOSITE way– as the energy released when two gaseous ions come together. So our lattice energies will be exothermic, or negative. However, everything else about thee videos applies.
Also, here is the answer key for the
Lattice Energy Worksheet. Be prepared to discuss on Monday.
chemistry matters 
Lattice energy is the enthalpy change when 1 mole of a crystal lattice is turned into its seperated gaseous ions, under standard conditions. lattice enthalpy increases as ionic size decreases and ionic charge increases.
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In these videos, I learned about lattice energy and what makes covalent and ionic bonds. A metal and nonmetal can form a covalent bond if the difference in electronegativity is less than 1.7. If the difference between 2 elements is greater than 1.7, they form an ionic bond.
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These videos covered lattice energy, covalent bonds, and ionic bonds. Lattice energy exists in a greater magnitude for smaller compounds with more highly charged constituent ions in comparison to larger compounds with ions with less charge. A general rule for telling if a bond is ionic or covalent is seeing if the difference in electronegativity is greater than (ionic) or less than (covalent) 1.7.
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If the difference in the electron negativity of the two elements is bigger than 1.7, then the bond is ionic; if it is less than 1.7, then the bond is covalent. If the difference in the electron negativity of the two elements is between 0 – 0.3, then the bond is non-polar covalent bond; If it is between 0.3 and 1.7, then the bond is polar covalent bond.
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