An element P (atomic number 20) reacts with an element Q (atomic number 17) to form a compound. Answer the following questions giving reason:
Write the position of P and Q in the Modern Periodic Table and the molecular formula of the compound formed when P reacts with Q.
Atomic number of element P = 20
Electronic configuration of element P = 2, 8, 8, 2
Atomic number of element Q = 17
Electronic configuration of element Q = 2, 8, 7
The position of P in the Modern Periodic Table:
Period (Number of shells) = 4
Group (Electrons in outer-most shell) = 2
The position of Q in the Modern Periodic Table:
Period (Number of shells) = 3
Group (Electrons in outer-most shell) = (10 + 7) = 17
When P reacts with Q, it looses the two valence electrons (valency 2). These two valence electrons are accepted by two Q atoms (valency 1). Hence, the formula of the compound formed between P and Q is PQ2 .