Question

For a hypothetical case let value of l is defined as 0, 1, 2, 3.... (n+1) for principle quantum number n

1) Atomic number of 1st noble gas is 8
2) Atomic number of 1st alkali metal is 9
3) carbon has electron in 2p_z
4) element with atomic number 13 has half filled valence shell. ​

Answer 1

Answer:

4

Explanation:

Answer 2

For a hypothetical case let value of l is defined as 0, 1, 2, 3.... (n+1) for principle quantum number n

To check which one of the following is correct...

1. Atomic number of 1st noble gas is 8
2. Atomic number of 1st alkali metal is 9
3. carbon has electron in 2p_z
4. element with atomic number 13 has half filled valence shell.

solution : for n = 1 , l = 0, 1, 2

for l = 0, subshell is s

for l = 1, subshell is p

for l = 2, subshell is d

so electric configuration is 1s² , 2p⁶ , 1d¹⁰

so for first noble gas , atomic no = 2 + 6 + 10 = 18

so option (1) is incorrect.

configuration of first alkali metal is 1s², 1p⁶ , 1d¹⁰, 2s¹

so atomic no = 2 + 6 + 10 + 1 = 19

option (2) is also incorrect.

electronic configuration of Carbon = 1s² 1p⁴

so, option (3) is incorrect because carbon atom doesn't have electron in 2p_z

for atomic no, Z = 13

electronic configuration = 1s², 1p⁶ , 1d⁵ ( half filed d subshell)

so option (4) element with atomic number 13 has half filled valence shell, is correct.