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?

Question

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

Answer 1

The correct answer is B. They have valence electrons in the same energy level.

Nitrogen (atomic number 7) and oxygen (atomic number 8) are both in Period 2 of the periodic table. This means they have their valence electrons in the same energy level (the second energy level). Nitrogen has 5 valence electrons, while oxygen has 6 valence electrons, so they do not have the same number of valence electrons (thus option C is incorrect). They also do not have the same number of electrons (option D is incorrect). They are in the same period, so they share the same energy level for their valence electrons (thus option A is incorrect).