Pupil sheet · Isotopes
Isotopes — return questions
Name ______________________ Date ____________
Use one to two weeks after the lessons. Keep the notes and the lesson closed.
1. deduce / explain
Oxygen has two common isotopes, 168O and 188O. (a) State the numbers of protons, neutrons and electrons in an atom of each. (b) An oxide ion has a charge of 2−. Write the symbol of the oxide ion formed from oxygen-18, with its mass number, proton number and charge. (c) (Supplement) Water made with oxygen-18 is called heavy-oxygen water. Explain why it gives the same result as ordinary water in the anhydrous copper(II) sulfate test, but has a greater mass for the same volume.
(a) Protons, neutrons and electrons in each isotope
(b) The symbol of the oxide ion (you may type it in words: the letter, the mass number, the proton number and the charge)
(c) Same test result, greater mass: explain
2. calculate
Bromine has two isotopes. Calculate the relative atomic mass of bromine. Give your answer to one decimal place.
| Isotope | Mass number | Abundance (%) |
|---|---|---|
| bromine-79 | 79 | 50.7 |
| bromine-81 | 81 | 49.3 |
Relative atomic mass, Ar: ______________ unit ________