Final answer:
Beryllium, with atomic number 4, is an alkaline earth metal located in the second period and second group of the periodic table, characterized by a low atomic radius and high ionization energy.
Step-by-step explanation:
The element with atomic number 4 is beryllium, an alkaline earth metal. On the periodic table, beryllium is located in the second period and the second group, which is the column of elements beneath helium.
The atomic model indicates that beryllium's fourth electron would fill the remaining space in the 2s orbital, confirming its position in the 2s block of the periodic table, where alkaline earth metals reside.
Beryllium's properties are compatible with its placement on the periodic table as it has a low atomic radius and a high fourth ionization energy relative to its neighboring elements in the same period.