why does ionization energy increase as atomic number increases?

Question

I need help on Chem homework

Answer 1

Hi Brandon,

 

The general trend is that ionization energy increases as you go right on the periodic table across a row (also called a period), and decreases as you go down a column (also called a group). There are various levels of explanation for this phenomenon but I think the most useful is that the valence elections (the electrons in the outermost orbitals or shell) are held closer to the nucleus as you go right across the periodic table. For example, the valence electrons in florine (atomic number 9) are held closer to the nucleus than the valence electrons in carbon (atomic number 6). According to electromagnetic force law, the force between two charges increases as the distance decreases, so the closer an electron is to the nucleus the stronger the force on the electron. Ionization energy is the measure of how much energy is takes to remove an electron from an atom. To do that you have to overcome the force holding the electron to the nucleus, so the stronger the force the more energy is required. This means that the ionization energy increases because the force holding the valence electrons increases as atomic number increases across a row.

 

Hope this helps!