Question

The energy of an electron in the ground state (n = 1) for He⁺ ion is −xJ, then that for an electron in the n = 2 state for Be³⁺ ion in J is:

Options

• −4x

• `-4/9 x`

• −x

• `-x/9`

Answer 1

−x

Explanation:

For He⁺:

E_n = `-13.6 (Z^2/n^2)`

= `-13.6 (2^2/1^2)`

= −13.6 × 4

= −54.4

= −xJ

For Be⁺³:

E_n = `-13.6 (Z^2/n^2)`

= `-13.6 (4^2/2^2)`

= −13.6 × 4

= −54.4

= −xJ