what element has four energy levels and two electrons on its outer shell
I would look in the vicinity of Calcium on the periodic table.
To determine the element that has four energy levels and two electrons on its outer shell, we need to refer to the periodic table. The periodic table consists of elements arranged in order of increasing atomic number and grouped based on similar properties.
First, let's identify the elements that have four energy levels, also known as electron shells. The electron shells are numbered from 1 to 7, starting from the innermost shell. Elements in the fourth period of the periodic table have four electron shells.
Next, let's focus on elements that have two electrons in their outermost shell, also known as the valence shell. The number of valence electrons determines the chemical properties of an element. Elements in Group 2 of the periodic table have two valence electrons.
Taking both criteria into consideration, we find that the element with four energy levels and two electrons on its outer shell is Beryllium (Be), which is in group 2 and period 2 of the periodic table.