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Topic: Physical states  (Read 4901 times)

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Tom

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Physical states
« on: June 28, 2004, 08:14:05 AM »
I'm having a difficult time figuring out which one of these statements about the general trends of the physical states of the elements is correct? I think the first and third are correct.
   
Most metals have low boiling points.
   
the boiling points for the group VII elements increase as the molecular  weight increases.
   
Most nonmetals have high melting points.
   
In general, the melting points of the transition metals decreases as you go down the periodic table.


Offline Donaldson Tan

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Re:Physical states
« Reply #1 on: June 28, 2004, 09:10:58 AM »
Metals definitely don't have low boiling points. If you mistook this for low melting point, then I must tell you only alkali metals (group 1) exihibit low melting point.

Group VII elements occur as diatomic molecules naturally. Their intermolecular bonding is Van Der Waal's in nature. Their boiling point will definitely increase with molecular weight (as it means these molecules also contain more electrons, hence stronger intermolecular bonding).

Most non-metals have low melting point, with reference to their structures.

Melting point of transition metals increases down the periodic table because there are more delocalised electrons, consequently stronger metallic bond. Hence, the increase in melting point.

Only the 2nd statement is incorrect.
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Tom

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Re:Physical states
« Reply #2 on: June 28, 2004, 12:55:38 PM »
I understand, thanks for explaining this to me!

Limpet Chicken

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Re:Physical states
« Reply #3 on: June 28, 2004, 03:36:11 PM »
Don't forget though, it isn't STRICTLY only group one metals that have low melting points, lead, mercury and gallium also have pretty low melting points too. Mercurs as you know is a liquid at room temperature, lead you can melt with a torch, and gallium will liquify when held in the hand.

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