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How is it that atoms with equal numbers of protons and electrons are described as "electrically neutral" when the proton is 1,800 times more massive than the electron?

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2 Answers 2

Do not confuse mass with charge. Although the proton is more massive, the magnitude of its positive charge is equal to the magnitude of the electron's negative charge. Hence, neutral atoms!

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Due to different masses the charge distribution within an atom is a complicated function of distance. But outside the atom, at far distances the electric and magnetic fields become very small, nearly zero so at far distances the atom is like an empty space - nothing reveals its presence. If you do not touch it, you do not feel it.

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"If you do not touch it, you do not feel it." So your answer to the question of charge neutrality of an atom is that we're too far away to measure it, so we won't know? This is confusing and doesn't seem to answer the question. –  John Apr 20 '11 at 21:34
    
Huh. I mean, this isn't the clearest answer to the question as stated... but -4 votes? –  wsc Apr 20 '11 at 23:35
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