Two representative elements, nitrogen and oxygen, are in the same period of the periodic table. Which statement correctly describes the atoms of the two elements?

A. They have valence electrons in the same energy level.
B. They have the same number of valence electrons.
C. They have the same number of electrons.
D. They have valence electrons in different energy levels.

1 answer

The correct statement that describes the atoms of nitrogen and oxygen is:

A. They have valence electrons in the same energy level.

Here's the reasoning:

  • Nitrogen (N) is in period 2 and has an atomic number of 7, meaning it has 7 electrons and its electron configuration is 1s² 2s² 2p³.
  • Oxygen (O) is also in period 2 and has an atomic number of 8, with an electron configuration of 1s² 2s² 2p⁴.

Both nitrogen and oxygen have their valence electrons in the same outermost energy level (n=2).

The other options can be evaluated as follows:

  • B. They have the same number of valence electrons. (Incorrect: Nitrogen has 5 valence electrons while oxygen has 6.)
  • C. They have the same number of electrons. (Incorrect: Nitrogen has 7 electrons and oxygen has 8.)
  • D. They have valence electrons in different energy levels. (Incorrect: They both have valence electrons in n=2.)

Thus, option A is correct.