review2v1 - McCord/Vanden Bout Exam 2 Review Topics Fall...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Which Chapter/Sections are covered? All of Chapter 13 and Chapter 14 sections 1-6. Concentrate on the subject matter that was emphasized in class and on the homeworks. Come in mentally prepared to answer at least 25 questions, maybe more. Once again, you need to understand the theory and concepts – getting a homework question right does not necessarily mean you really understand the material. Ask yourself why you chose an answer. Try to explain the question to someone else. Ionic vs Covalent Know the difference in these two types of bonding and compounds. Ionic compounds: These are all a continuous lattice of alternating cations and anions. We refer to their identities as formula units and NOT as molecules. They are held together by strong coulombic attractions which leads to nearly all (99.9%) of them being solids at room temperature. Not just solid but brittle solids – they will shatter if you whack them hard enough. If you want to melt them you need to get well above 500˚C and for some, well above 1000˚C. If you do get them melted, the resulting liquid WILL conduct electricity due to all the positive and negative ions flowing around. Let’s not say this: ionic bonds are the transfer of electrons. Yes, we’ve all heard that. The fact is simply there are lots and lots of ions (cations and anions) already out there in nature. These ions can and do find one another and they STICK together. THAT my friend is an ionic bond. As far as I’m concerned, the concept of electron transfer is best reserved for oxidation/reduction reactions and electrochemistry. To say that NaCl is made by taking one electron away from sodium and giving it to chlorine is to speak of an oxidation/reduction reaction – the result of which (in this particular case) is an ionic compound. My point is that you do NOT need to transfer any electrons to get an ionic bond or compound – you need IONS – cations and anions – find them where you may. Lattice Energies: Know what this is and what factors increase/decrease the values. You don’t have to memorize the equation but DO look and see how charge is quantified and how distance factors in. Covalent compounds: These consist of discrete molecules. These generally are NOT a continuum of covalent bonds (OK, there are network solids which do this – but those are exceptions and are rare in the grand scheme of things). 99.9% of all covalent compounds are molecules – we DO refer to their identities as molecular formulas. They can be solids, liquids, or gases at room temperature. It all depends on their intermolecular forces (we’ll get there soon enough after this exam). Covalent bonds are identified by the sharing of electron pairs by two nuclei. Lewis Electron Dot Structures
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/06/2008 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas at Austin.

Page1 / 3

review2v1 - McCord/Vanden Bout Exam 2 Review Topics Fall...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online