Question

Find the block labeled ? in Figure 2. What is its atomic number? How many valence electrons does it have? Which of the elements shown in Figure 2 will it most resemble?

Answer 1

That is Magnesium. its atomic number is 12 and has 2 valence electrons. it will most resemble beryllium (Be)

Answer 2

The atomic number of the element is 12. The name of the element is magnesium. It has two valence electrons. The element it most resemble is Be, beryllium.

looking at the periodic table given in the question, we can see that the element we are looking for belong to group 2, thus, its properties will be similar to that of Be, which belong to the same group. The electronic configuration of magnesium is 2, 8, 2, this implies that, it has two electrons on its outermost shell.