Question

Among the elements 2He4, 7N14, 12mg24
and 4Be8, the elements which belong
to the same period in the modern
periodic table are

​

Answer 1

Answer:

Explanation:

First period He

Second period. Be,N

Third period. Mg

Answer 2

Beryllium and nitrogen belongs to the same period of the modern periodic table.

• The period of an element can be detrmined by the principal quantum number of the outermost electron of the element.
• The electronic configuration of helium is 1s2, hence it belongs to the first period of the modern periodic table.
• The electronic configuration of magnesium is 1s2,2s2,2p6,3s2 , hence it belongs to the third period of the modern periodic table.
• The electronic configuration of beryllium and nitriogen are 1s2,2s2 and 1s2,2p3 respectively, hence they belong to the second period of the modern periodic table.