Unit 6 Blog Entry

The purpose of the sticky tape lab that we were assigned a few weeks ago was to observe how electrons move and how charges work. We did this by rubbing two pieces of tape together making a positive and negative piece of tape, then seeing how the tape interacted with materials given to us, determining whether all of those additional materials were either positive, negative, or neutral. That really gave us good background for our conductivity lab.  We figured out from the sticky tape lab that metals have a weak positive core and nonmetals have a strong positive core, so some particles are better at attracting negative charges. That helped us figure that different compounds conduct electricity better or worse. The model of the atom for us was a clearer picture from here on out (different cores cause different compounds to have different charges). The purpose of the conductivity lab was to figure out which substances were ionic or molecular based on how they conducted electricity. This lab taught us that the compounds composed of a nonmetal and a metal (ionic) were usually better conductors. Why were the ionic compounds better conductors than the molecular? Well we figured out that ionic compounds have more “wiggle room” for their electrons. They are more free to move which allows the electrical current to run through better. Ionic compounds are made of one metal and one nonmetal, while molecular compounds are made up of two nonmetals. Here is a video for a deeper explanation of ionic and molecular compounds. https://www.youtube.com/watch?v=PKA4CZwbZWU . While naming ionic compounds and molecular compounds, the first step is to determine whether it contains a metal or not. If it does, that means it’s an ionic compound. Now that you’ve determined that the compound is ionic, you want to see if it contains a transition metal. If so, you will name the metal as it is on the periodic table plus a roman numeral depending on the charge. If the compound does not contain a transition metal, then you name it as it appears on the periodic table, unless it contains more than two types of atoms. If it has a polyatomic ion, name it without changing the ending, if it does not, name it as it appears but change the ending to “ide”. You can use this chart as a reference while naming ionic and molecular compounds…

Ionic compounds are fairly simple to write formulas for. First you write the symbols off each element (EX: MgCl). Each column on the periodic table has a charge (1A, 2A, 5A, 6A, 7A) you determine the charge by looking at which column the element is in (EX: Mg+2 Cl -1). Then take the charge of each and apply them to the opposite element (EX: MgCl2). Remember, you do not have to write the charge if it is 1.  To write Ionic compounds with transition metals, you first write the name of the transisiton metal from the periodic table. (Fe)Then, you write the name of the non-metal. (FeCl). You then determine the charges of both and switch them as a subscript to the other element. (FeCl2). When writing these out in actual words, you write the tranition element out with its charge in roman numerals. (Iron II), This applies to all when dealing with transition metals. Then add the non metal's name tho the end. (Iron II Chloride). When writing an ionic compounds dealing with polyatomic ions, you first need to looks at the two polyatomic ions. A polyatomic ion is more than one atom bonded together. The cation is always witten first, then comes the anion. (Ca SO3). Then determine charges. (Ca+2 SO3-2). Then you combine them. (CaSO3). That is a very simple example. When there is more of one of the exact polyatomic ion, you must put the polyatomic ion in parenthesis. (Ba3(PO4)2). It is the same idea if the polatomic ion is positive instead of negative. You write the positive polyatomic ion first (NH4). Then add the negative element and make sure the charges are subscripts. (NH4Cl). When writing these out, you write the cations normal name, and the anions normal name, unless the anion is a non-polyatomic ion, in that case you would add "ide" to the ending. Most ternary ionic compounds are made of a metal and a polyatomic ion. They consist of three different elements. You first write the metal as is. (Li). Then you write the polyatomic ion as is (NO3). Then move the charges of the two into subscripts (LiNO3). This is called Lithium Nitrate.  When writing the formula for molecular compounds, you simply look at the prefix in front of the word and apply it as the charge on the element. Naming molecular compounds is even easier. First you look to see if there is a metal. If not, you use the Greek prefixes (mono, di, tri, tetra, penta, hexa, hepta, octa, nona, and deca), to show the number of each atom. You must also change the ending of the last element to “ide”. Make sure to NEVER use mono on the first element. This activity is great practice for a better idea on how to name ionic and molecular compounds. https://www.quia.com/rr/180365.html