Video Transcript
If a neutral atom has 12
protons in its nucleus, how many electrons does it have?
To figure out the answer of
this question, let’s recall the basic structure of an atom. Every atom has a nucleus made
up of some number of protons and neutrons. And that nucleus is surrounded
by orbiting electrons. In this question, we’re told
that we have a neutral atom that has 12 protons in its nucleus. If we consider the protons to
be these rose-colored spheres in our nucleus, then we can count one, two, three,
four, five, six, seven, eight, nine, 10, 11, 12 of them. For this atom to be considered
a neutral atom as it is, that means the charge of these protons must be balanced
out by the charge of the orbiting electrons. We can recall then what the
relative charge of a proton is and what the relative charge of an electron
is.
Now, independent of one
another, a proton does have a specific amount of electric charge, and so does an
electron. But in this case, we’re not
concerned with that specific amount, but rather just how the charges compare to
one another. From that perspective, we can
recall that the charge of a proton is equal and opposite the charge of an
electron. So if we let the relative
charge of a proton be plus one, then the relative charge of an electron would be
negative one. This tells us that if we add
together a proton and an electron, the combined electric charge of that
combination is zero. In other words, together, the
particles are overall electrically neutral. That helps us figure out the
answer to our question, which asks, how many electrons does this neutral atom
with 12 protons have?
If the charge of one electron
effectively cancels out the charge of one proton, then that must mean our
neutral atom has the same number of protons as electrons. We have 12 protons in our
nuclear core. And right now, we have one,
two, three, four, five, six, seven, eight, nine electrons. We’ll need to add three more to
this picture so that the total negative charge, negative 12, balances out the
total positive charge of positive 12. And this then tells us our
answer. We need to have 12 electrons
for this to be a neutral atom. That’s how many will balance
out the charge of the 12 protons in the nucleus.
