Final answer:
The alkaline earth metals are in Group 2 and the halogens are in Group 17 of the modern periodic table, where elements with similar properties are grouped together.
Step-by-step explanation:
In the modern periodic table, the alkaline earth metals are located in Group 2, also referred to as Group 2A. This group includes elements such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The halogens are found in Group 17, known as Group 7A, comprising elements like fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
The modern periodic table is designed to group elements with similar properties and electronic configurations together. This is exemplified by the location of the alkaline earth metals and halogens, which exhibit characteristic behaviors making them unique amongst their peers within the periodic table. For instance, alkaline earth metals are known for their two valence electrons and form +2 cations, while halogens have seven valence electrons and typically gain one electron to form -1 anions.