It is 10:15 and I am going to call it a night......Any last issues??? good night. I hope you do well...... Night guys good luck . Since there are no recent questions, I am going to take a break.... I will check back around 9:45. In the meantime, write questions below and I will answer when I get back. Delocalization? see this metallic bonding link. http://www.drkstreet.com/resources/metallic-bonding-animation.swf The concept of delocalization also applies to resonance. When pi bonds are delocalized, the electrons can move throughout the molecule. Any more questions?.....it is 9:55 Vernesha---can you see the conversation here? Yes OK we will stay above line 44. thank you . How do you do the equations were it says which of the following compounds have the highest melting point? LiF or BF3 or CF4 or NF3 or OF2 the highest melting point would be between the compounds with the strongest bond. LiF is ionic---very strong. The others are molecules, which are held to each other by van der waals attractions ---weak attractions. so, the highest boiling point would be the LiF. K Is anyone still here? yes. What is an oxidation reduction reaction? He answered that somewhere down at the bottom for ivy I think k thanks oxidation is the loss of electrons and reduction is the gain of electrons (because gain of electrons reduces charge.) So, an oxidation reduction reaction is any reaction in which the atoms in the chemical formulas change charge. An example would be in the halogen activity lab where the elemental chlorine replaced the bromine. Both the chlorine and and bromine changed their charge. In the precipitation lab, nothing changed charge, so they were not oxidation reduction reactions. are we going to have to find the polarity of molecules? yes. All you have to do is determine the geometry and consider the charge vectors. If the vectors cancel, the molecule is non polar. If the vectors don't cancel, the molecule is polar. Oh ok What is metallic bonding bonding in metals. see this link......http://www.drkstreet.com/resources/metallic-bonding-animation.swf I might be a few minutes late. If so, post questions now, and I will catch up. thanks Does everyone have a copy of the practice final? The real final is very similar. Mr. Howe This isnt really about the final, but have you graded labs yet? I haven't graded labs yet. Also could you explain number 3 What is the question.Do you mean number 3 on the final review sheet? how do you know when a pair of atoms is held together by a covelant bond two nonmetals form covalent bonds. A metal and a non metal form an ionic bond. on the periodic table are metalloids metals? Metalloids have properties of both metals and non metals. They are found between the two. Boron, Silicon, Arsenic, etc....running diagonally through the p block from boron down to the right. so there are only 7 right ? yes There are MANY more metals on the periodic table than non metals. wait waaaaaah ??? how do you know if it is metsl metals are all of the elements to the left of the metalloid line. Metallic properties increase as you move left on the periodic table. If this helps. true wait but why is cl not a metal Cl is on the right side of the metalloid line. The non-metal side im so sorry i should really learn my right from my left, next question... so are transition metals the ones in the middle... yes. the d sublevel block thanks can we color code the periodic table we use for the finals for like, where the metals,non-metals and such are? or print one out? I will give you one with charges, like those I have distributed in class.okay If equal volumes of 0.1M NaOHnand 0.1 M HCl are mixed, the resulting solution will contain salt and why is the answer H2O cations change partners, so the products are HOH and NaCl. HOH is H2O number 3 is which type of radiation continues in a straight line when passed through an electric field? In order NOT to bend, when passed through an electric field, the radiation would not have a charge. The gamma radiation is the only option that does NOT have a charge. I. Have lots of trouble writing equations will this be on the test Nothing more complicated than the NaOH and HCl equation above, where the cations change partners. How similar will the test be to the practice one? quite similar. There will also be 7 dot diagrams like those in the 53. will you be asking us questions about staticelectricity on the final? no what is an oxidation reduction reaction oxidation is the loss of electrons and reduction is the gain of electrons (because gain of electrons reduces charge.) So, an oxidation reductions reaction is any reaction in which the atoms in the chemical formulas change charge. An example would be in the halogen activity lab where the elemental chlorine replaced the bromine. Both the chlorine and and bromine changed their charge. In the precipitation lab, nothing changed charge, so they were not oxidation reduction reactions. Aq stands for dissolves in a solution right?yes. I think "absolution" is theological. : ) Are you still there? There was a connection issue for a few minutes. How does a non polar + no polar bond work If two molecules are sitting next to each other and both are non polar, the electrons from one molecule repel the electrons in the neighboring molecule. This causes both molecules to become temporarily polar. While the temporary polarity lasts, the molecules attract each other. see this link. http://intro.chem.okstate.edu/1515SP01/Lecture/Chapter12/LondonDisp.html So is it the same with polar+polar bonds? this type of van der Waals attraction happens between both polar and non polar molecules. But with non polar molecules, this is the only attraction between them. Very weak attractions-- so non polar things tend to have low melting points and boiling points. Sorry mr.howl the link doesn't work w/ my mobile device OH... the link to okstate. The picture is that of the oscillating electrons in the orange balls that I showed in class. Ok My wife just came home and I need to take a short break. I will be back in about 15 minutes. it is now 8:13. Please keep posting questions and I will answer as soon as I return. How can you tell if an atom is held together by a covalent bond? atoms are held together by attractions between the nucleus and electrons. Two atoms can be bonded to each other by ionic or by covalent bonds. Covalent bonds from between two non metals. Ionic bonds form between metals and non metals. what is an oxidation half reaction? can you explain this. Oxidation is loss of electrons, so the best example would be the reaction that we discussed in the halogen lab. for example, when Br- was replaced by Cl2, the bromine lost electrons. The reaction would be 2Br- --> Br2 + 2 e- The bromine changed from -1 to 0 okay i think i get it. where is the practice test that you said would be online? I decided to frame the final primarily on the practice test that I gave you in class, so I didn't post it. I tried to keep things a bit simpler. If you need a copy of the one I gave in class, I will post it quickly.... okay, i have it. Could you explain endothermic and exothermic? exothermic means energy goes out and endothermic means energy goes in. For example, it takes energy to melt ice, so energy would go in....endothermic. or, it takes energy to add an electron to a full s or p sublevel, so the addition of an electron to an alkaline earth metal or a noble gas is endothermic. That is, the electron affinity of alkaline earth metals and noble gasses is positive, and the energy change is endothermic. will we be able to use our trend graphs on the test? no. you need to know that okradius decreases left to right within a period (series) and increases top to bottom within a family(group). If you know these trends and the other definitions, you should be able to reason through any question I ask. for example, small atoms are small because they hold electrons tightly, so they would have high ionization energies. Can you explain delocalization in pi bonds? If there is more than one logical place to draw a double bond like in SO2, the pi bond (second bond in the double bond) is actually spread through the whole molecule, and is thus said to be delocalized. What just happened? I am going to the top of the page..... please post there. Maybe Vernesha will be able to see.