Question

the elements of a period of the periodic table are given below in order from left to right with one of its element missing: na mg al si s cl ar to which period do these elements belong?

Answer 1

phosphorus is missing and these elements belongs to period.

Answer 2

Answer:

phosphorus : atomic no. 15 is missing

Explanation:

Na-atomic no. 11

E. C. = 2,8,1

Mg - atomic no. 12

E. C. =2,8,2

since theses elements have three shells.

so all these elements belong to 3rd period