Question

Which of the following is correct regarding the first ionization potential of Na, Mg, Al and Si?

• A. $Na<Mg<Al>Si$
• B. $Na>Mg>Al>Si$
• C. $Na<Mg<Al<Si$
• D. $Na>Al<Mg>Si$
• E. $Na<Al<Mg<Si$

Answer 1

Answer: (E)

The energy required to remove an electron completely from the outermost orbit of an isolated gaseous atom is called the ionization potential of the element. Across a period, first ionization potential increases except few atoms of elements. Here it is to be remembered that removal of an electron from a p-orbital is easier than from a completely filled 5-orbital. So, the first ionization potential of Al is less than Mg. So, the correct sequence is: $Na<Al<Mg<Si$