Identify the number of electrons in the outermost shell of the following elements. Class 9
Identify the number of electrons in the outermost shell of the following elements. Class 9
Question 1.
Identify the number of electrons in the outermost shell of the following elements: (Page 152) Class 9
(i) [latex]{ }_6^{12} \mathrm{C}[/latex]
(ii) [latex]{ }_9^{19} \mathrm{F}[/latex]
(iii) [latex]{ }_{14}^{28} \mathrm{Si}[/latex]
Answer:
(i) Carbon has atomic number = 6. Electronic configuration = 2, 4. The outermost shell is the L-shell (n = 2) and it contains 4 electrons.
(ii) Fluorine has atomic number = 9. Electronic configuration = 2, 7. The outermost shell is the L-shell and it contains 7 electrons.
(iii) Silicon has atomic number = 14. Electronic configuration = 2, 8, 4. The outermost shell is the M-shell and it contains 4 electrons.
Question 2.
Write the electronic configuration of the elements having atomic numbers 12, 16 and 18. (Page 152) Class 9
Answer:
- Atomic number 12 (Magnesium, Mg): Electronic configuration = 2, 8, 2. (K = 2, L = 8, M = 2)
- Atomic number 16 (Sulfur, S): Electronic configuration = 2, 8, 6. (K = 2, L = 8, M = 6)
- Atomic number 18 (Argon, Ar): Electronic configuration = 2, 8, 8. (K = 2, L = 8, M = 8)