Why do the alkali metals have low ionization energies but relatively large atomic size?

Question:

Why do the alkali metals have low ionization energies but relatively large atomic size?

Periodic properties

The elements in same group in periodic table have similar electronic configuration, and so their properties are also similar. So, trends in periodic table are very important.

Answer and Explanation:

Alkali metals are the elements in group I of periodic table. They have one electron in their outermost orbit.

By loosing that one electron, these metals can achieve noble gas configuration, and become very stable. So, alkali metals have low ionization energies.

As they have one extra shell than the previous noble gas, so they have bigger atomic size than the noble gas.

Also, comparing them with group II metals, group II metals have 2 electrons in their outermost shell. Atomic size decreases in moving from left to right in period, as the positive charge in nucleus also increases due to increase in number of protons. So, group I alkali metals have larger atomic size than group II metals.


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Metals on the Periodic Table: Definition & Reactivity

from General Studies Science: Help & Review

Chapter 27 / Lesson 45
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