covalent molecular and covalent lattice what is the difference (1 Viewer)

[s_t_a_r1234]

how do you distinguish between covalent molecular and covalent lattice, are they both classified under covalent compounds?

 

[Dreamerish*~]

how do you distinguish between covalent molecular and covalent lattice, are they both classified under covalent compounds?

This is preliminary, so I assume you're talking about the allotropes of carbon.

Yes, they're both classified as covalent compounds, which by definition are compounds which have bonds formed by atoms sharing electrons.

Covalent molecular means, in the case of graphite, that each carbon atom is bonded to only three other carbon atoms to form a planar structure. Three bonds per carbon atom leaves each carbon atom with a free valence electron. These excess electrons form a delocalised electron cloud over the whole ring system. It's like layers, stacked together, with electron clouds between them. They slide over each other easily and therefore graphite is slippery. The delocalised electrons are responsible for graphite's electricity-conducting abilities.

Covalent network consists of carbon atoms that are covalently bonded to each other via angle bonds, which are tetrahedrally arranged. Each carbon is bonded to four other carbon atoms, which leaves no delocalised electrons - this is why diamond does not conduct electricity. This network structure is much stronger because there are no layers. The entire structure is connected together by covalent bonds.

Hope that helps.

 

[Trebla]

Covalent Molecular - This is where you have atoms covalently bonding into a small molecule. This type of of bonding is where covalent MOLECULES are formed. The intramolecular forces are strong, but the intermolecular forces are weak because there are usually no non-bonding electrons. The boiling/melting point is low and the crystalline structure formed by the molecules, are held together weakly. Examples include, O2, CO2, N2, NH3, H2SO4 etc

Covalent Lattice - This is where you have atoms covalently bonding everywhere in an almost infinite array to form a solid network or lattice. A common example is diamond where each carbon atoms attaches itself to four other carbon atoms and eac of those four carbon atoms attach to another four carbon atoms and so on. Since they are bonded everywhere, there is a strong intramolecular force which makes such structures have extremely high melting/boiling points and hardness. Examples include, Diamond (C) and Quartz (SiO2)

Both are covalent compounds because they involve sharing of electrons

 

[zeek]

[Quote = Dreamerish*~ ]allotropes of carbon.[/Quote]

err... Covalent Molecular and Network bonds aren't only restricted to allotropes of carbon (unless you were just using them as an example).

You might also find it handy to study the shape of the covalent bond, e.g. triagular planar, tetrahedral, V-Shaped etc. and revise the VSEPR model (Valence Shell Electron Repulsion Theory).

 

[zeek]

[Quote = Dreamerish*~ ]allotropes of carbon.[/Quote]

err... Covalent Molecular and Network bonds aren't only restricted to allotropes of carbon (unless you were just using them as an example).

You might also find it handy to study the shape of the covalent bond, e.g. triagular planar, tetrahedral, V-Shaped etc. and revise the VSEPR model (Valence Shell Electron Repulsion Theory).

 

[Dreamerish*~]

err... Covalent Molecular and Network bonds aren't only restricted to allotropes of carbon (unless you were just using them as an example).

If you look again, I said:

This is preliminary, so I assume you're talking about the allotropes of carbon.

In the preliminary course, the only example you need to know is carbon - in great detail, too.

 

[Derkk]

Hmm this helps me as well. Cheers

 

[f(sex)]

how about phosphorous?
is that covalent molecular or covalent lattice?

 

[studentcheese]

I can't tell whether a substance if covalent molecular or covalent network by looking at the formula. How would I differentiate between the two?

 

[annabackwards]

I can't tell whether a substance if covalent molecular or covalent network by looking at the formula. How would I differentiate between the two?

You should just know. Common examples of covalent lattice, graphite (pure carbon) are diamonds (pure carbon) and silicon dioxide. Basically all other compounds in the HSC are covalent molecular.

 

[GUSSSSSSSSSSSSS]

rippin that chem up anna

but yes, as she said, silicon dioxide (sand) and diamond are (im pretty sure) the only two covalent lattices you wuld need to know for HSC

 

[undalay]

Graphite is a covalent network. Not covalent molecular.

 

[annabackwards]

rippin that chem up anna

but yes, as she said, silicon dioxide (sand) and diamond are (im pretty sure) the only two covalent lattices you wuld need to know for HSC

Aha, it's the only chem revision i've done in the holidays oO

Graphite is a covalent network. Not covalent molecular.

Oh yes, let's not forget graphite.

Now for my question: You can't have a covalent molecular substance if it's composed of only one element right?

 

[undalay]

Aha, it's the only chem revision i've done in the holidays oO


Oh yes, let's not forget graphite.

Now for my question: You can't have a covalent molecular substance if it's composed of only one element right?

Yes you can, there are many examples.
O2, H2, N2 (basically all the diatomic halogens). Don't forget ozone O3, etc.

 

[annabackwards]

Yes you can, there are many examples.
O2, H2, N2 (basically all the diatomic halogens). Don't forget ozone O3, etc.

Ah thanks, forgot about them XD

Man i need to do some chem =="

 

[RexGenius]

I think graphite is a covalent layer not a covalent network.