Write the correct symbol, with both superscript and subscript,
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Question

Write the correct symbol, with both superscript and subscript, 
for each of the following. (d) the isotope of calcium that has an equal 
number of protons and neutrons.

Accepted Answer

Hey everyone in this example, we need to give the correct symbol for the isotope of magnesium with the same number of protons and neutrons. So we want to recall the fact that within a chemical symbol or isotope symbol, our mass number which is represented by the term A. Is equal to our number of neutrons added to our number of protons. We want to recall that our chemical symbol or isotope symbol is going to be represented by our element, which is X. We have our mass number in the left hand superscript A and our atomic number Z, which is represented in the left hand subscript. So Z again is our atomic number. So the prompt mentions the atom magnesium. So we would have the substitution for X as our atom magnesium here, we want to recall that we can find magnesium in Group two A of our periodic tables corresponding to the atomic number 12, so Z would equal 12 and we would place 12 here in the left hand subscript. We also would recognize that our magnesium in the periodic table has the atomic mass of 24. Specifically 24.31 am us. And we want to recall that our mass number, which is our variable here a is represented as a shorthand for our mass number. However, we also know that our mass number is also equal to our number of neutrons plus our number of protons. And so because we know that the atomic mass for magnesium is 24, we would assume that we have 12 protons added to 12 neutrons to equal our mass number 24. And so we would go ahead and place 24 in the left hand superscript of our chemical symbol for magnesium 24 Isotope, and this would be our final answer to complete this example. So I hope that this helped you. But if you have any questions, please leave them down below. Otherwise, I'll see everyone in the next practice video.

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