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Methanol with an isotopically labelled carbon atom is shown in Figure 1. The superscript gives the mass number of the labelled atom.
Use the isotope label in Figure 1 and the periodic table to determine the numbers of protons and neutrons in the labelled atom’s nucleus.
For a neutral atom of this isotope, state the number of electrons, the charge of its nucleus, and where its electrons are located relative to the nucleus.
A representative sample of natural boron is characterized for use in a neutron-absorbing material. It contains the isotopes ¹⁰₅B and ¹¹₅B. The relative isotopic masses and relative atomic mass of the sample are:
| Isotope | Relative isotopic mass |
|---|---|
| ¹⁰₅B | 10.0129 |
| ¹¹₅B | 11.0093 |
The relative atomic mass, Aᵣ, of the sample is 10.811.
For the ion ¹⁰₅B⁺, state the number of protons, neutrons and electrons.
Explain why ¹⁰₅B and ¹¹₅B are isotopes.
Assuming the sample contains only these two isotopes, determine the percentage abundance of ¹⁰₅B. Give your answer to three significant figures.
A student claims that ¹⁰₅B and ¹¹₅B must have identical physical properties because they have the same number of protons. Explain why this claim is not justified.
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