Energy and radius of first Bohr orbit of He+ and Li2+ are [Given RH = 2.18 10-18 J, a0 = 52.9 pm]
- En (Li2+ ) = -19.62 10-16 J; rn (Li2+ ) = 17.6 pm En (He+ ) = -8.72 10-16 J; rn (He+ ) = 26.4 pm
- En (Li2+ ) = -8.72 10-16 J; rn (Li2+ ) = 17.6 pm En (He+ ) = -19.62 10-16 J; rn (He+ ) = 17.6 pm
- En (Li2+ ) = -19.62 10-18 J; rn (Li2+ ) = 17.6 pm En (He+ ) = -8.72 10-18 J; rn (He+ ) = 26.4 pm
- En (Li2+ ) = -8.72 10-18 J; rn (Li2+ ) = 26.4 pm En (He+ ) = -19.62 10-18 J; rn (He+ ) = 17.6 pm
Answer
(3) En (Li2+ ) = -19.62 10-18 J; rn (Li2+ ) = 17.6 pm En (He+ ) = -8.72 10-18 J; rn (He+ ) = 26.4 pm
Solution
For hydrogen-like species: En = -RH Z2n2, rn = a0 n2Z; here n = 1.
Li2+ (Z = 3): E1 = -2.18 10-18 9 = -19.62 10-18 J; r1 = 52.93 = 17.6 pm
He+ (Z = 2): E1 = -2.18 10-18 4 = -8.72 10-18 J; r1 = 52.92 = 26.4 pm
Answer: (3)