Group IV melting poins

[ChemSiddiqui]

Hi, I just read Group IV today and was surprised to know that Carbon melting point was higher than that of lead or tin. The explaination the book gave was that the giant covalent bonding in carbon doesn't allow the electron to move and thus it requires greater energy to separate the bonds and melt carbon. While metallic bonding shown by tin or lead is weak.

 

the idea didn't sink in. Can any 1 help.

[YT2095]

in metal the electrons are delocalised and there`s no real Bonds to break, no single metal ion has any real claim to a Specific electron, they are all free to move about (that`s why they conduct so well also).

in Carbon the electrons are Shared, each Carbon atom shares electrons with 3 other Carbon atoms, there is only 1 free electron left delocalised and that exists between the layers of carbon molecules (that`s why it conducts a little bit).

 

it takes Energy to break these bonds, that energy comes from greater heating in this case.

[insane_alien]

in Carbon the electrons are Shared, each Carbon atom shares electrons with 3 other Carbon atoms, there is only 1 free electron left delocalised and that exists between the layers of carbon molecules (that`s why it conducts a little bit).

 

side note: This is the graphite form of carbon, the rarer and more expensive type(diamond) bonds to 4 other carbons and doesn't have any free electrons.

[YT2095]

side side note: and that`s why Diamonds don`t conduct at all

[BhavinB]

side side note: and that`s why Diamonds don`t conduct at all

 

Side side side note: don't conduct at room temperatures or typical voltages / power (see diamond electronic devices)

[insane_alien]

side side side side note(this is getting ridiculous): diamond electronic devices are a result of doping ala silicon electronic devices. diamond is capable of acting as a semiconductor.

[John Cuthber]

(side)^(n+1) note

Tin can also act as a semiconductor or a superconductor.