Pupil sheet · Isotopes
Isotopes — final check
Name ______________________ Date ____________
Work alone, with the lesson closed. Answer every question; there are no hints.
1. define / deduce / explain
The symbols show two atoms of nitrogen. (a) Define isotopes, using these two atoms as the example. (b) A nitride ion formed from nitrogen-15 has 10 electrons. Write its symbol with the mass number, the proton number and the charge. (c) (Supplement) Explain why nitrogen-14 and nitrogen-15 have the same chemical properties.
(a) Define isotopes, using these atoms
(b) The symbol of the nitride ion (you may type it in words: the letter, the mass number, the proton number and the charge)
(c) Why they have the same chemical properties
2. calculate / explain
Silicon has three isotopes. (a) Calculate the relative atomic mass of silicon to one decimal place. Show your working. (b) Explain why the relative atomic mass of silicon is very close to 28.
| Isotope | Mass number | Abundance (%) |
|---|---|---|
| silicon-28 | 28 | 92.2 |
| silicon-29 | 29 | 4.7 |
| silicon-30 | 30 | 3.1 |
(a) The relative atomic mass of silicon, with working
(b) Why it is close to 28