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Chemistry Bonding help please!!

I don't get it..
When are there intermolecular forces? (Ionic/metallic/covalent bonding)
I know covalent bonds are strong yet they are easy to break because they have weak forces between the bonds etc etc

bonding is something I just don't yet.. It always says ignore reference to intermolecular forces (which I thought occured in covalent bonding) so I'm really confused

Help please?!?!

Reply 1

shanz123

Covalent isn't easy to break , molecular substances are because of the reason you said

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Reply 2

EmmaC_

Original post by shanz123

Covalent isn't easy to break , molecular substances are because of the reason you said

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I thought molecular structures were covalentenly bonded... Oh dear I'm going to fail xD

Reply 3

username2303351

Covalent bond such as simple covalent bond like molecules like oxygen, they have strong covelant bonds between their atoms but there are weak intermolecular forces between the neighboring molecules so meaning between each atom in this example of oxygen which are very weak but between the atoms themselves they have strong bonds, Since there is weak intermolecular forces between neighboring molecules then that means the melting and boiling point is lower as you will need a lower temp to break theses bonds. This is only for simple molecular covalent.

Reply 4

shanz123

That is true that is why the individual atoms in molecules in molecular substance are hard to break because they are covalently bonded, however the forces between each molecule are very weak and they are not covalent. If you can get a hand of the cgp book it has a great image that makes it much more simpler!

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Reply 5

Meegan543210

Giant covalent structures such as silicon dioxide graphite and diamond all have strong covalent and intermolecular forces. A lot of energy is needed to break the intermolecular forces NOT the covalent bonds. Graphite has weak intermolecular forces between the layers (or you can say no covalent bonds) and hence layers can slide due to these weak forces holding them together. Simple covalent structures such as carbon dioxide, methane water etc have STRONG covalent bonds but weak intermolecular forces so not much energy is needed to break the intermolecular forces because they are weak and again the strong covalent bonds are NOT broken. There are strong electrostatic forces of attraction in a giant ionic lattice and strong electrostatic forces of attraction between the positive metal ions and negative electrons in metallic bonding. Hope I helped and good luck for tomorrow :smile:

(edited 7 years ago)

Reply 6

Imsophie

Original post by EmmaC_

Firstly, ionic, covalent and metallic bonding are a type of intramolecular force not intermolecular force (inter means between, like international means between countries)

Ionic, covalent and metallic bonds hold molecules and compounds together by bonding the electrons together.
Covalent bonds - strongest out of the three. Very hard to break. Require lots of energy to break. If in a simple molecule (such as a chlorine molecule CI2) they are broken easier than say in a complex giant structure such as silicon dioxide.
Ionic - weaker than covalent bonding. Unlike covalent bonding (which is the sharing of electrons), ionic bonding is the transferring of electrons. This forms ions (charged atoms). for example if a neutral lithium atom (with one electron in its outer shell ) transfers it to a neural fluorine atom (with 7 electrons in its outer shell) then both atoms become charged and form an ionic compound. As electrons are negatively charged, fluorine which had gained an electron has a charge of -1 and is now no longer electrically neutral. Lithium has lost an electron and so has more positively charged protons than electrons. Lithium has a positive +1 charge. Just remember ionic bonding is between oppositely charged ions.
Metallic bonding is obviously bonding within metals. E.g all group 1metals donate their outer shell electron into a 'sea' of delocalised electrons that move through structure. This is what allows metal their property of electrical conductivity.
Hope this helps!

Reply 7

Big white

Original post by EmmaC_

That's the bit which is wrong
it's GCSE

There are 2 types of covalent bonding

simple covalent(or just covalent): Take CH4 for example, the bond between the carbon and hydrogen are strong but the forces between the molecules are weak

giant covalent: These are things like diamond and graphite where there are strong bonds everywhere but diamond is just one big thing and there aren't any molecules of diamond

For ionic bonding is the "electrostatic force of attraction between negatively charged ions" <-- very good thing to use in the exam

Reply 8

alchima

Other people have explained it well but I just wanted to add something...
Think of a structure like diamond or silicon dioxide. It has huge networks of atoms and covalent bonds. If you do C3 you will know that there are different bond energies for bonds between different atoms. A carbon to carbon bond requires around 347kJ/mol to break. So if you have loads of these bonds in a structure like diamond, it becomes much more difficult to break them and requires more energy. It's practically impossible to melt diamond it will just burn.

(edited 7 years ago)

Reply 9

EmmaC_

Original post by 11lmizo

Oh okay.. I thought silicon dioxide was a simple molecular covalent. Sothe question is:
Silicon Dioxide has a very high melting point
Other substances are added to silicon dioxide to make glass. Glass melts at a lower temperature than silicon dioxide.
Suggest why.
I put there are weak intermolecular forces between the bonds which can be easily broken by low temperatures (but on the mark scheme it says ignore reference to intermolecular forces)

Reply 10

EmmaC_

Original post by EmmaC_

oh wait I just realised silicon dioxide isn't a simple molecular.. Never mind 😂 so if it's a giant covalent you don't talk about intermolecular forces? You just say the bonds are strong and the forces between the bonds are strong?

This might help

Thank you everyone, this has been super helpful!

Reply 13

Midge May

Original post by EmmaC_

I had the same problem understanding bonding, then i checked out a chemistry video on Topic 2a bonding & structure of elements found on GCSE Crammers 9-1 on you tube. It really helped me understand how weak, strong & very strong covalent bonds work. 🤗