[Darren]

Why is phosphorus soft? The element P₄. I read somewhere about molecular geometry playing a part in this property, but i cant seem to explain it properly why it is soft? Also, i havent learnt much detain on molecular geometry yet, only on chem bonding have a learnt a lot more. But i still cant get a reason to account for this property. Is it soft because the layersof atoms can slide over each other in the element? But why would there be laters of atoms in the first place if its a non metal, not like graphite.

[discodermolide]

Why is phosphorus soft? The element P₄. I read somewhere about molecular geometry playing a part in this property, but i cant seem to explain it properly why it is soft? Also, i havent learnt much detain on molecular geometry yet, only on chem bonding have a learnt a lot more. But i still cant get a reason to account for this property. Is it soft because the layersof atoms can slide over each other in the element? But why would there be laters of atoms in the first place if its a non metal, not like graphite.

Have a look at this page;
http://en.wikipedia.org/wiki/Phosphorus

[Darren]

I didnt find any info on why phosphorus is soft in wikipedia.

[Hunter2]

I think its because we have only a low number of atoms (4) in the molecule. These atoms dont have charges.

1 or 2 atoms in an molecule we have gas, liqiuid and or soft material. more it is still soft material, like phosphoros or sulfur.

[Darren]

I think its because we have only a low number of atoms (4) in the molecule. These atoms dont have charges.

1 or 2 atoms in an molecule we have gas, liqiuid and or soft material. more it is still soft material, like phosphoros or sulfur.

Is sulfur soft? I thought its a solid at r.t.p.? But if thats the case, we would expect all the halogens to be soft as well, since they are diatomic. But iodine and astatine are solids at room temperature.

[Hunter2]

What is in your words soft and solid. A solid material can be soft like ice cream.
So Iodine is solid but also soft. sulphur, it depends what modification is present:  crystalline ß-sulfur to soft like rubber y-sulfur

[Darren]

What is in your words soft and solid. A solid material can be soft like ice cream.
So Iodine is solid but also soft. sulphur, it depends what modification is present:  crystalline ß-sulfur to soft like rubber y-sulfur

Ooh i see i see. Hmm i dont know what soft means excatly as well. That was the exact question that my school gave to us. And they havent told us the answer yet. Maybe i will try asking my teacher to see what kind of response they would want to that question.

[Wastrel]

To a certain extent there is a flaw in the question, you may as well ask why carbon is black and soft.  Graphite is grey and soft, amorphous carbon is black and soft, diamonds are clear and hard.  White phosphorus is waxy and very soft, purple and black phosphorus are brittle and harder, but I don't know how much harder.  In general the more cross linking, the harder the material.  Small molecules held together by weak forces tend to be soft, big covalent lattices tend to be hard.

If in doubt, assume hard and soft refer to mohs scale, i.e. what scratches what.