Question

Write True or False.

The second period contains eight elements and the third period contains eighteen elements.

• A. True
• B. False

Answer 1

The correct option is B False

PERIOD

A period in the periodic table is a horizontal row of chemical elements. All elements in a row have the same number of electron shells.

1. The second period contains the elements lithium(Li), beryllium(Be), boron(B), carbon(C), nitrogen(N), oxygen(O), fluorine(F), and neon(Ne). In a quantum mechanical description of atomic structure, this period corresponds to the filling of the second (n = 2) shell, more specifically its 2s and 2p subshells.
2. The third period contains eight elements: sodium(Na), magnesium(Mg), aluminium(Al), silicon(Si), phosphorus(P), sulfur(S), chlorine(Cl), and argon(Ar). In a quantum mechanical description of atomic structure, this period corresponds to the buildup of electrons in the third (n = 3) shell, more specifically filling its 3s and 3p subshells.

Concluding statement:

1. So the given statement is false. both contain 8 elements.