The first five ionization energies (IE_1 through iE_5) of a Period 2 element have the following pattern: Make a reasonable guess about which element this is. Enter its chemical symbol below.
There is a huge difference in ionization energy between IE4 and IE5.
This means lots of energy are required to remove the 5th electron.
So, after 4 electrons are removed, the element has acquired noble gas configuration,.
So, ether are 4 valence electrons in the element.
The element in period 2 with 4 valence electrons is Carbon