Anonymous
Anonymous asked in Science & MathematicsChemistry · 8 years ago

Chemistry HELP! I need to find protons neutrons and electrons out of a formula!?

Hi i need to work out an equation, please help!

I need to find out how many protons - how many neutrons and how many electrons are in the formula

31, 15 P3-

Please help and elaborate on how you come to the answer? My chemistry teacher confused me!

1 Answer

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  • 8 years ago
    Best Answer

    A = atomic weight = 31 = p + n

    p = no. of protons

    n = no. of neutrons

    p = 15

    so, p + n = 15 + n = 31

    so, n = 16.

    now e = no. of electrons.

    e = p when neutral, but here there is -3 charge, so there are 3 electrons in excess.

    So.e = p + 3

    e = p + 3 = 15 + 3 = 18.

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