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Predict the block, periods and groups to which the following elements belong.i. Mg (Z = 12) ii. V (Z = 23) iii. Sb (Z = 51) iv. Rn (Z = 86) v. Na (Z = 11) vi. Cl (Z = 17) |
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Answer» i. Mg (Z = 12): Atomic number of Mg is 12. Electronic configuration is 1s2 2s2 2p6 3s2. Block: Since the last electron enters s subshell (3 s), Mg belongs to s-block. Period: n = 3. Therefore, it is present in the third period. Group: For s-block element, group number = number of valence electrons = 2. Hence, it belongs to group 2. ii. V (Z = 23): Atomic number of V is 23. Electronic configuration is 1s2 2s2 2p6 3s2 3p6 3d3 4s2. Block: Since the last electron enters d subshell (3d), V belongs to d-block. Period: n = 4. Therefore, it is present in the fourth period. Group: For d-block elements, group number = 2 + number of (n – 1) d electrons = 2 + 3 = 5. Hence, it belongs to group 5. iii. Sb (Z = 51): Atomic number of Sb is 51. Electronic configuration is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p3. Block: Since the last electron enters p subshell (5p), Sb belongs to p-block. Period: n = 5. Therefore, it is present in the fifth period. Group: For p block elements, group number = 18 – number of electrons required to complete octet = 18 – 3 = 15. Hence, it belongs to group 15. iv. Rn (Z = 86): Atomic number of Rn is 86. Electronic configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6. Block: Since the last electron enters p subshell (6p), Rn belongs to p-block. Period: n = 6. Therefore, it is present in the sixth period. Group: For p block elements, group number = 18 – number of electrons required to complete octet = 18 – 0 = 18. Hence, it belongs to group 18. v. Na (Z = 11): Atomic number of Na is 11. Electronic configuration is 1s2 2s2 2p6 3s1. Block: Since the last electron enters s subshell (3s), Na belongs to s-block. Period: n = 3. Therefore, it is present in the third period. Group: For s-block element, number of the group = number of valence electrons = 1. Hence, it belongs to group 1. vi. Cl (Z = 17): Atomic number of Cl is 17. Electronic configuration is 1s2 2s2 2p6 3s2 3p5. Block: Since the last electron enters p subshell (3p), Cl belongs to p-block. Period: n = 3. Therefore, it is present in the third period. Group: For p block elements, group number = 18 – number of electrons required to complete octet = 18 – 1 = 17. Hence, it belongs to group 17. |
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