# The Naked Scientists Forum

### Author Topic: How many electrons in a child?  (Read 1107 times)

#### kantalope

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##### How many electrons in a child?
« on: 23/03/2013 18:33:20 »
At the Cambridge Science Festival, someone asked "How many electrons in an 8 year old?"

Just counting the top ten elements (so no trace things like copper)

Going off the 50%ile for 7 yo girls – this is 25 kilos (UK growth chart: Royal College of Paediatrics and child health newbielink:http://www.rcpch.ac.uk/system/files/protected/page/NEW%20Girls%202-18yrs(4TH%20JAN%202012).pdf [nonactive])

Oxygen 65% = 16.25 kilos; 1015.66 moles; 6.116x10^26 atoms x 8 electrons = 4.89x10^27 electrons
Carbon 18% = 4.5 kilos; 374.66 moles; 2.26 x10^26 atoms x 6 electrons = 1.35x10^27 electrons
Hydrogen 10% = 2.5 kilos; 2480.30 moles; 1.49 x10^27 atoms x 1 electron = 1.49 x10^27 electrons
Nitrogen 3% = .75 kilo; 53.55 moles; 3.22x10^25 atoms x 7 electrons = 2.25x10^26 electrons
Calcium 1.5% = .375 kilo; 9.35 moles; 5.63 x10^24 atoms x 20 electrons = 1.41x10^26 electrons
Phosphorus 1% = .25 kilo; 8.07 moles; 4.86 x10^24 atoms x 15 electrons = 7.29 x10^25 electrons
Potassium .35% = .0875 kilo; 2.24 moles; 1.34 x10^24 atoms x 19 electrons = 2.56 x10^25 electrons
Sulfur .25% = .0625 kilo; 1.95 moles; 1.17 x10^24 atoms x 16 electrons = 1.88 x10^25 electrons
Sodium .15% = .0375 kilo; 1.63 moles; 9.82 x10^23 atoms x 11 electrons = 1.08 x10^25 electrons
Magnesium .05% = .0125 kilo; .51 moles; 3.07 x10^23 atoms x 25 electrons = 7.68 x10^24 electrons

For a total of 2.374 x10^27  or 2,374,000,000,000,000,000,000,000,000 atoms   :)
And 8.232 x10^27 or 8,232,000,000,000,000,000,000,000,000 electrons   :0

Grownups could just divide their weight in kilos by 25 to find their atom/electron counts.

Using newbielink:http://www.convertunits.com [nonactive] to convert to moles
moles multiplied by Avogadro's number (6.022x10^23) to get number of atoms

Kantalope, US
« Last Edit: 14/07/2013 11:13:55 by chris »

#### The Naked Scientists Forum

##### How many electrons in a child?
« on: 23/03/2013 18:33:20 »