Rank the following elements by increasing atomic radius: carbon, aluminum, oxygen, potassium.
The correct order with respect to increasing atomic radius is
An important thing to notice about these four elements is the fact that only two of them,
This aspect will allow you to easily rank them with respect to increasing atomic radius, since both of the periodic trends in atomic size are on display here.
Let's look at
As you move to the right within a period, the number of protons elements have increases simultaneously with the number of electrons; however, electrons are being added to the same energy level across a period, which means that the increasing number of protons allows the nucleus to exert more pull on these electrons, which in turn makes the atomic radius smaller.
As mentioned before,
This happens because electrons are now being added to higher energy levels, further away from the nucleus, which weakens the nucleus' pull. Another reason for the increase in atomic radius is the electron shielding effect, which states that the electrons in the higher energy levels are being shielded by those closer to the nucleus, further reducing the nucleus' pull on them.
This means that