# The Naked Scientists Forum

### Author Topic: What determines weight?  (Read 3835 times)

#### DoctorBeaver

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##### What determines weight?
« on: 13/08/2008 23:04:06 »
Iron is a lot heavier than, say, lithium. But what determines its weight? Is it purely the number or nucleons, or does how closely packed the atoms are also have a bearing?

• Neilep Level Member
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##### What determines weight?
« Reply #1 on: 13/08/2008 23:16:32 »
I was led to believe it was down to a bit of each.

#### DoctorBeaver

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##### What determines weight?
« Reply #2 on: 14/08/2008 08:37:34 »
Is either more important?

#### DonBrown

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##### What determines weight?
« Reply #3 on: 14/08/2008 13:36:38 »
Which weighs more, a pound of lead or a pound of feathers?
Or if you prefer, a kg of Li or a kg of Fe?

#### DoctorBeaver

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##### What determines weight?
« Reply #4 on: 14/08/2008 13:53:29 »
Don - that's not what I was getting at. 1cm3 of Fe would weigh a lot more than the same amount of Li.

#### lightarrow

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##### What determines weight?
« Reply #5 on: 14/08/2008 14:28:42 »
Iron is a lot heavier than, say, lithium. But what determines its weight? Is it purely the number or nucleons, or does how closely packed the atoms are also have a bearing?
With a few exceptions, metals are all packed in the maximum way, so what is left is every atom's density which in turn, generally, increases with the number of nucleons (down a group)

#### DoctorBeaver

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##### What determines weight?
« Reply #6 on: 14/08/2008 17:24:47 »
Thank you, Alberto.

• Neilep Level Member
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##### What determines weight?
« Reply #7 on: 14/08/2008 17:43:02 »
But then we have non-metals with diverse structures and compounds. What about sunflower oil and honey. One floats on the other. Packing definitely has an affect here.

#### Bored chemist

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##### What determines weight?
« Reply #8 on: 14/08/2008 19:12:39 »
The atoms in lead are roughly twice the mass of the atoms in silver, yet the densities of the metals are roughly the same. I think they are both fairly nearly close packed structures. The difference in this case is the size of the electron cloud around the atoms.

Incidentally quite a lot of the atoms in honey are oxygen, relatively few of the atoms in sunflower oil are, and oxygen is the heaviest atom in either of the 2 compounds.

#### The Naked Scientists Forum

##### What determines weight?
« Reply #8 on: 14/08/2008 19:12:39 »