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How do I figure out how many neutrons are in an atom?Neutrons

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mnewsham | Student, Grade 9 | eNotes Newbie

Posted September 9, 2012 at 10:27 PM via web

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How do I figure out how many neutrons are in an atom?


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nicoledesilva | Student, Grade 11 | (Level 1) Salutatorian

Posted September 10, 2012 at 12:10 PM (Answer #1)

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Suppose you have the periodic table cell. Example for oxygen, 16 is at the top, O in the middle and 8 at the bottom. Okay? I hope you got that. Now 16 is the proton number + neutron number and 8 is the neutron number. So, you subtract 8 from 16, 16 - 8 = 8, Therefore, 8 is the proton number.


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kavya--kammana | Student, Grade 12 | (Level 1) Valedictorian

Posted September 14, 2012 at 7:09 AM (Answer #2)

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  1. proton number= electron number= atomic number
  2. atomic mass of an element is proton number + neutron number.
  3. so for getting neutron number u  have to subtract proton number from atomic mass.
  4. eg:  atomic mass of sodium is 23
  5.        atomic number of sodium ( proton number / electron number) is 11
  6.    no. of neutrons = 23- 11=  12.
  7. eg: atomic mass of Carbon is 12
  8. atomic number = 6
  9. no. of neutrons = 12-  6 = 6.

hope u got it.....

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ncchemist | eNotes Employee

Posted September 23, 2012 at 12:20 AM (Answer #3)

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The nucleus of an atom is made up of protons and neutrons.  The atomic number of an element is the total number of protons it contains.  The mass number is the total number of protons and neutrons that it contains.  So subtracting the atomic number from the mass number is how you can determine the number or neutrons in an element.  For carbon, the atomic number is 6 and the mass number is 12, so the number of neutrons is 12-6=6.  In actuality, all elements are found in nature with varying numbers of neutrons in their nuclei.  These compounds that differ only by the number of neutrons in their nuclei are called isotopes.  For example, carbon-12 is the example that I mentioned above.  But carbon-13 has 13-6=7 neutrons and the two are isotopes of each other (different isotopes of carbon).


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tuvshee | Student, Grade 11 | (Level 1) Honors

Posted September 10, 2012 at 12:58 AM (Answer #4)

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You subtract atomic number from mass number.

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