How Many Atoms are in a Dog?
Most recent answer: 10/22/2007
Q:
How many atoms are in a dog?
- Cathy (age 6)
Leal School, Urbana
- Cathy (age 6)
Leal School, Urbana
A:
We put our team of engineers, chemists, and physicists to work on this
problem, and finally came up with an answer. Let’s say you’ve got a
pretty big German Shephard who weighs 100 pounds. There would be about
3,000,000,000,000,000,000,000,000,000 atoms in him!
(Scientists often write big numbers like that in "scientific notation", like this: 3*10^27. That just means three followed by twenty-seven zeros.)
So how many is that? Well, if you had a grain of sand for every atom in that dog, you’d have enough to cover the entire United States with a layer of sand 65 miles deep!
Atoms are SO SMALL, that you need piles and piles of them to build anything big enough to even see!
What about a chihuahua? They usually weigh only about five pounds, so you’d only need 150,000,000,000,000,000,000,000,000 atoms to make one.
(Scientists often write big numbers like that in "scientific notation", like this: 3*10^27. That just means three followed by twenty-seven zeros.)
So how many is that? Well, if you had a grain of sand for every atom in that dog, you’d have enough to cover the entire United States with a layer of sand 65 miles deep!
Atoms are SO SMALL, that you need piles and piles of them to build anything big enough to even see!
What about a chihuahua? They usually weigh only about five pounds, so you’d only need 150,000,000,000,000,000,000,000,000 atoms to make one.
(published on 10/22/2007)
Follow-Up #1: Reprise for number of dog atoms
Q:
I was curious how you arrived at the answer for the question on the number of atoms in a dog. I'd like to see the math and science behind this answer if possible.
- Roshan (age 22)
Urbana
- Roshan (age 22)
Urbana
A:
The answer posted was in response to a question from a 6 year old so was kept to a bare minimum of technical details, but the gist of the answer remains the same: how much does the dog weigh and what is the average weight of an atom in a dog.
The main constituent of dogs, as well as humans, is water: between 60 and 70%. There's some calcium and nitrogen as well as iron but I'll make the calculation assuming 100% water. You can make your own corrections if you wish. The gram molecular weight of water is 18.05 grams. This amount of water contains one Avogadro's number worth of molecules, 6.02e+023. That's a bunch. See: . So for a 25 kilogram dog you get (25*1000/18.05)*6.02e+023 = 8.3e+026 molecules of water. Water contains 2 Hydrogen and 1 Oxygen atoms so you can multiply this answer by 3 to get 2.5e+027 atoms. I hope this helps.
LeeH
The main constituent of dogs, as well as humans, is water: between 60 and 70%. There's some calcium and nitrogen as well as iron but I'll make the calculation assuming 100% water. You can make your own corrections if you wish. The gram molecular weight of water is 18.05 grams. This amount of water contains one Avogadro's number worth of molecules, 6.02e+023. That's a bunch. See: . So for a 25 kilogram dog you get (25*1000/18.05)*6.02e+023 = 8.3e+026 molecules of water. Water contains 2 Hydrogen and 1 Oxygen atoms so you can multiply this answer by 3 to get 2.5e+027 atoms. I hope this helps.
LeeH
(published on 07/29/2012)