Question

What solid contains two types of bonds?
Iodine
Silicon (IV) Oxide
NaCl
Zinc

???

Answer 1

silicon (IV) oxide has covalent and ionic caracter

Answer 2

HOW

Answer 3

The answer is NaCl.
Reason:
http://answers.yahoo.com/question/index?qid=20080628035614AAQEWCl

Answer 4

Hmm. What I don't understand is how I could apply the concepts i've learnt in A Levels to this question.

Answer 5

@Shivam_Bhalla I'm not satisfied with that answer... although it may be correct, I don't know how I could have known that..

Answer 6

@Kryten explanation?

Answer 7

This was actually a question on my recent A Level MCQ exam.

Answer 8

@Areesha.1D, I'd like to offer a different answer: iodine! Here's how I interpreted it - Aren't there two types of bonds: intramolecular, and intermolecular? In this case, I2, or iodine, is held together through a covalent bond between the two iodine atoms. But, I2 molecules are attracted to one another through Van der Waals forces - this is what keeps the solid as a whole together. So in essence, you have two levels of bonds: one that keeps the atoms attached, one that keeps the solid together.

If you look at SiO2, Zn, and NaCl - aren't the bonds that hold the atoms together the bonds that hold the /entire/ solid together? They are all (I believe) complex lattice structures in which the bond between any of its constituents is simply replicated to a macroscopic level. This is not the case with iodine.

Of course, I could be mistaken; if @Kryten or @Shivam_bhalla could offer their reasoning as well that'd be great.

Answer 9

@kma230 Your interpretation is exactly what I thought of as I was was sifting through my mind for possible answers to that option BUT it said two types of CHEMICAL bonds... that's was got me stumped :/ .......

Answer 10

Sorry, I didn't mention the "chemical" part....

Answer 11

@kryten would it be because silicon dioxide has a polar covalent bonding?

Answer 12

"If the Zn is in a bar of zinc metal, it forms metallic bonds. If the Zn is combined with a nonmetallic atom, it will form an ionic bond." I also found this answer online, i'm not sure if it could be applied here or not...

Answer 13

Be careful. That Yahoo Answers answer is complete nonsense. First, NaCl is about as prototypical a pure ionic compound as you are likely to find. No serious chemist would characterize the bonding in crystalline NaCl as "polar covalent." Secondly, even when a bond is reasonably characterized as polar covalent, that does NOT imply "two different types" of bond exist. You have one type: polar covalent. It is a covalent bond, in which the electrons tend to favor one end of the bond, that's all.

Mind you, in a detailed MO theory characterization of the bonding, you can certainly formalize what percent contribution there might be to your MO from ionic configurations -- but that is really just an artifact of constructing the MO from a basis set. Or, speaking more broadly, we talk about a percentage ionic character just because we have difficulty describing a stationary quantum state with mental images from classical mechanics. It's like the fact that we have to use multiple resonance structures to describe certain bonding situations when we restrict ourselves to the "basis set" of Lewis structures. But that does NOT mean a molecule flips back and forth between resonance structures. In the same way, a compound with polar covalent bonds does NOT flip back and forth between being ionic and nonpolar covalent. There is no sense in which two types of chemical bonding are occuring.

Personally, I wonder if you might be overthinking this question. The most obvious answer to me is simply SiO2, because you have SI-Si bonds and Si-O bonds. That's two different covalent bonds, right? By contrast iodine and zinc are both elements, so there is only one type of covalent bond between the atoms, and NaCl has no covalent bonds at all.

Answer 14

Thanks for the very informative reply, @Carl_Pham.

Answer 15

@Carl_Pham , Very informative reply . Next time, I will think twice before linking to a yahoo answer :)

Answer 16

i tell you its SiO2 cause i study for about a year Si and Si compounds and i know its SiO2. i just came from all day visit to a rubber factory and im tired as a dead beat rat so i dont have power to explain...

Answer 17

^^Awesome. Haha @Kryten no problem. Thanks guys!!