A little help with Chemistry?

[The 1 and Only Lady Gaga]

First of all, I live in Singapore, and the education system is different from the U.S, so I will attempt to make it as "American" as possible so people will understand it.

The problem, I am always getting by with a C in Chemistry, but I always get A in Physics and Biology. I am worried by Chemistry grade will be the end of me one day, like preventing me from going to a college of my choice and whatnot.

Anyway, the chapter I am on is on Covalent and Ionic Bonding. I am having loads of trouble here.

Question: Silicon Dioxide is said to have a structure similar to diamond. Explain in terms of structure and bonding whether silicon dioxide would have a high or low melting point.

My answer: High melting point, because of the strong covalent bonds in a tetrahedral shape between the molecules, a lot of energy is required to break the covalent bonds.

How many marks did I get? 1 out of a potential 3. How did I lose the 2 marks? The teacher is an asshole, he asked to find out ourselves.

Question: Explain one physical property that would be exihibited by Magnesium Phospide.

My answer: WTF? I have no idea how to answer this.

Obviously 0 marks.

Would some kind soul in Smogon University help me? It would be appreciated.

 

[MrIndigo]

Appeal to the head of faculty. If your teacher cannot show why he deducted marks, he can't deduct them.

 

[The 1 and Only Lady Gaga]

Appeal to the head of faculty. If your teacher cannot show why he deducted marks, he can't deduct them.

Unfortunately, the same teacher teaches all 3 Sciences of Physics, Chemistry & Biology, so he must have deducted them for some reason.

 

[Jimbo]

SiO2, I'm pretty sure, is an interesting molecule that doesn't really follow normal rules. When you draw it, you have to draw a bunch of them connected together. It acts like a covalent network solid (like Diamond). You could say the lattice energy is very high.

As for MgP, you could've said something true about any Ionic Solid and it probably would've been right. (I don't remember a bunch of qualities off the top of my head, but stuff like hardness/brittleness or melting point would've worked).

If you really think he's grading you unfairly, talk to him in private after class or send you an email. I don't think it's really unfair that you got points off for those questions, since you didn't answer them completely. Even if you don't learn a question in a class, especially in Chemistry, it might be fair game for a test ;)

Anyway, Cong isn't really for homework help. If you need anymore help, feel free to post a VM on my wall. Good luck!