Thursday, 10/28/2010

Bonding Habits
We learned that by looking at the periodic table you could detemine weather or not an atom is a metal or a non-metal Be is a metal. Also we learned that metals form positive ions which means that it loses electrons as in Be it loses 2 electrons making its charge +2. In addition, if an atom is a non-metal then it gains electrons as in He it gains 1 electron making its charge -1. You can determine the amount of electrons an atom will be gaining/losing by looking at the periodic table or an electron configuration. We can also find the charge of an atom by comparing the amount of electrons and protons after the atom has formed an ionic bond.

Ionic Compounds
We learned how to predict the formula of an ionic compound. First you find the charges of the ions by them already being their or you have to find that atom on the periodic table and finding its charge when it forms an ion. Then, your goal is to make the charge of the ionic bond zero. To do this you need to either double one of the ions or find the least common dinominator. Then you write it positive ion then negative ion. Ex. K+ and O2- you want to make their overall charge zero so you have -2 from K so to even that out with a + you simply just make it K2 making the formula k2O. A more challenging problem would be when you have to add a sub number to both the positive and negative ions. Ex. Fe3+ and CO32- in order to find the formula for this ionic compound you must find the least common dinominator which in this case is 6 so you would need two Fe3+ and three CO32-. The answer for this would be 2Fe(Co3)3. You need parentheses for the Co3 because that is the original ion and you don't want to get confused with how many of that ion you need to make the ionic bond come out to zero so you NEED the perentheses. In some problems you are not going to have the charges given to you so you need to look at your periodic table and find out if the ion is positive or negative and how many electrons does it gain or lose.
Then you resume the original process. Ex. K and S K's charge is +1 and S's charge is 2-. So you need to K's to even out the one S so the formula would be this K2O.

Peter I
Ionic
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Period 2 Chemistry 2010