The table gives the energies required for electron transitions between three allowed orbits.
| Transition | Energy absorbed |
|---|---|
| P to Q | 2.5 × 10-19 J |
| Q to R | 4.0 × 10-19 J |
An electron starts in Q. It absorbs 4.0 × 10-19 J and then emits 6.5 × 10-19 J.
Which gives its final orbit and net energy change?
Orbit P; energy decreases by 2.5×10−19 J2.5\times10^{-19}\ \mathrm{J}2.5×10−19 J.
Orbit R; energy increases by 10.5×10−19 J10.5\times10^{-19}\ \mathrm{J}10.5×10−19 J.
Orbit P; energy increases by 2.5×10−19 J2.5\times10^{-19}\ \mathrm{J}2.5×10−19 J.
Orbit R; energy decreases by 2.5×10−19 J2.5\times10^{-19}\ \mathrm{J}2.5×10−19 J.
103 exam-style questions on Edexcel GCSE Physics 6.1 Atomic structure and isotopes, covering 6.1.1 Structure of the atom, 6.1.2 Isotopes: atomic and mass number, 6.1.3 Sub-atomic particles: masses and charges, and 6.1.4 Electron orbits and energy changes. Each one has a worked solution and a mark scheme showing where the marks go.