Question

Which of the following elements has its highest energy electrons in an "s" atomic orbital? radiium (Ra) neon (Ne) aluminum (Al) lanthanum (La)

Answer 1

It would be the one that has the highest orbital level on the s suborbital which in this case would be Ra

Answer 2

Answer: The correct answer is Radium (Ra).

Explanation:

Energy level having highest value of principle quantum number which is 'n' will have the highest energy electrons.

For the given options:

Radium (Ra): The number of electrons present in this element are 88 and electronic configuration of this element is $[Rn]7s^2$

It has 2 electrons in 's' orbital having n = 7.

Neon (Ne): The number of electrons present in this element are 10 and electronic configuration of this element is $[He]2s^22p^6$

It has 2 electrons in 's' orbital having n = 2.

Aluminium (Al): The number of electrons present in this element are 13 and electronic configuration of this element is $[Ne]3s^23p^1$

It has 2 electrons in 's' orbital having n = 3.

Lanthanum (La): The number of electrons present in this element are 57 and electronic configuration of this element is $[Xe]5d^16s^2$

It has 2 electrons in 's' orbital having n = 6.

Hence, the correct answer is Radium (Ra).