Writing symbols for atoms

Question

Which of the following is an incorrect representation for a neutral atom: 

108/47Ag

63/30Cu

30/15P

13/6C

6/3Li

Answer 1

There is a problem with this question. Whether an atom is neutral or not does not depend on the isotopic notation you showed above. Any isotope can exist in neutral or ionic form. As long as the atomic number matches the element, all of the notations above are valid, although they may not represent the most common or most stable isotope of each element. But they can all exist as neutral atoms or ions.

 

Here is a bit more information about each element:

• Silver is element 47, so the notation ¹⁰⁸₄₇Ag represents silver-108, an isotope of silver. Although this isotope has a mass close to the atomic mass on the periodic table, this particular isotope is not stable (half-life ~2.4min). The stable isotopes of silver are actually silver-107 and silver-109.
• Phosphorus is element 15, so the notation ³⁰₁₅P represents phosphorus-30. This is not a stable isotope of phosphorus and it only has a half-life of about 2.5min.
• Carbon is element 6, so the ¹³₆C represents carbon-13, a rare isotope of carbon, but a stable isotope of carbon nonetheless.
• Lithium is element 3, so ⁶₃Li represents lithium-6, the less common (7.6% abundance) of lithium's two stable isotopes (lithium-7 is more common, 92.4% abundance)

 

I hope this cleared up the issue.