# The Naked Scientists Forum

### Author Topic: How many atoms in a grain of sand ?  (Read 87134 times)

#### neilep

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##### How many atoms in a grain of sand ?
« on: 02/02/2007 15:45:49 »
I have been studying a grain of sand under my very poweful 10 X magnifying glass.

I still can not see the atoms.

My daughter (10 years) tells me they are a lot smaller than that...yeah right !!!..LOL..anyway...my best guess is that there could be about what 20-30 atoms in a grain of sand ?

My daughter (still 10 ) reckons there's billions !!..LOL...come on...get real !!..

Do I really have to move up to my 15 x magnifying glass to to see them or not ?

So, how many atoms are there in a grain of sand...she wins £10 if there is more than a hundred !!
I win a hug if there is less....I am confident.

« Last Edit: 04/02/2007 14:25:30 by neilep »

#### daveshorts

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##### How many atoms in a grain of sand ?
« Reply #1 on: 02/02/2007 16:11:24 »
Sand is made up of Silica this has the formula SiO2
silicon weighs 28 atomic units
Oxygen weighs 16 atomic units
so each SiO2 weighs 60 atomic units

there are 6.023 x 1023 atomic units in a gram. that is 6 with 23 zeros after it.

so there would be 6.023 x 1023 / 60 = 1x 1022 SiO2s in a gram
so
3 x 1022 atoms in a gram

Say a grain of sand is 1mm across it has a volume of 0.001cm3
1cm3 of sand weighs aboout 2.6g

so a grain of sand will
weigh 0.0026g

so to fing the number of atoms in a grain of sand we multiply the number of atoms per gram by the number og grams:

3 x 1022 x  0.0026g = 7.8 x 1019 atoms

or

78 000 000 000 000 000 000

Sorry Neil
« Last Edit: 02/02/2007 16:51:48 by daveshorts »

#### neilep

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##### How many atoms in a grain of sand ?
« Reply #2 on: 02/02/2007 16:33:38 »
Dave,

Are you sure ?..did you count them ?

Did you let slip your fingers on the '0' key ?

I am being prodded in the side by my daughter !!

*le sigh* she wins £10...and I get a hug anyway.

Thanks Dave.

#### Carolyn

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##### How many atoms in a grain of sand ?
« Reply #3 on: 02/02/2007 16:54:30 »
YAYYYYYY Charlotte!

#### neilep

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##### How many atoms in a grain of sand ?
« Reply #4 on: 02/02/2007 17:00:02 »
YAYYYYYY Charlotte!

Yep...she's quite the bright one...

LOL...Now she is saying that clouds are made from water vapor ..LOL LOL LOL ....when we all really know they are made from cotton wool !!..*le sigh*...she'll learn !!

#### Karen W.

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##### How many atoms in a grain of sand ?
« Reply #5 on: 04/02/2007 03:07:47 »
LOL Good Job Charlotte!! ...Go Get em..

And Neil She has already learned all she needs to know.....she has you wrapped right around her little finger where your supposed to be!!...Hugs to you both...LOL

#### neilep

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##### How many atoms in a grain of sand ?
« Reply #6 on: 04/02/2007 14:27:16 »
LOL Good Job Charlotte!! ...Go Get em..

And Neil She has already learned all she needs to know.....she has you wrapped right around her little finger where your supposed to be!!...Hugs to you both...LOL

LOL....you're soooo right there Karen Mam...

#### Karen W.

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##### How many atoms in a grain of sand ?
« Reply #7 on: 04/02/2007 14:32:18 »
Yes I know I am.. Your just a big softy!!! LOL LOL

#### The Naked Scientists Forum

##### How many atoms in a grain of sand ?
« Reply #7 on: 04/02/2007 14:32:18 »