Question

How do valence electrons vary across the periodic table?

Answer 1

The atomic number of the chemical element represents the number of electrons present in the atom of the chemical element. The valence electrons are present in the outermost orbital of the chemical element.

Complete step by step answer:
Moseley discovered the Modern Periodic law and states that the physical properties and the chemical properties of the chemical elements are the periodic function of their atomic number. In the modern periodic table the chemical elements are arranged according to their atomic number which keeps increasing as we move in the periodic table. As stated in the law, the atomic number of the chemical element is related to the physical and chemical behavior of the chemical element due to this reason the chemical element shows periodicity in their physical and chemical behavior. The atomic number of the chemical elements represents the number of electrons present in the atom of the element. The valence electrons are the electrons which are present in the outermost orbital of the electronic configuration.
The valence electrons vary across the periodic table. As we move from left to right across the periods in the periodic table the number of valence electrons increases.
Across the group, the number of valence electrons remains the same which shows that the chemical elements present in the same group have the same number of valence electrons. Example: elements present in 1 st group hydrogen, lithium, sodium have the same number of valence electrons that is 1.

Note: The property of the valence electrons are that they are the only electrons which take part in the chemical bonding. The valence electrons in a molecule can be represented as the bonding electrons or non-bonding electrons (lone pairs).