The question asks which pair of ions is not an iso-electronic pair. Iso-electronic species are atoms or ions that have the same number of electrons. To determine whether the given pairs are iso-electronic, we need to calculate the total number of electrons for each ion in the pair.
Fe2+ and Mn2+:
The atomic number of iron (Fe) is 26. Fe2+ means it has lost 2 electrons, so the electron count is 26 - 2 = 24.
The atomic number of manganese (Mn) is 25. Mn2+ means it has lost 2 electrons, so the electron count is 25 - 2 = 23.
Since Fe2+ has 24 electrons and Mn2+ has 23 electrons, they are not iso-electronic.
O2− and F−:
The atomic number of oxygen (O) is 8. O2− means it has gained 2 electrons, so the electron count is 8 + 2 = 10.
The atomic number of fluorine (F) is 9. F− means it has gained 1 electron, so the electron count is 9 + 1 = 10.
Since both O2− and F− have 10 electrons, they are iso-electronic.
Na+ and Mg2+:
The atomic number of sodium (Na) is 11. Na+ means it has lost 1 electron, so the electron count is 11 - 1 = 10.
The atomic number of magnesium (Mg) is 12. Mg2+ means it has lost 2 electrons, so the electron count is 12 - 2 = 10.
Since both Na+ and Mg2+ have 10 electrons, they are iso-electronic.
Mn2+ and Fe3+:
We have already calculated Mn2+ to have 23 electrons.
The atomic number of iron (Fe) is 26. Fe3+ means it has lost 3 electrons, so the electron count is 26 - 3 = 23.
Since both Mn2+ and Fe3+ have 23 electrons, they are iso-electronic.
Therefore, the pair that is not iso-electronic is Fe2+, Mn2+ as they have a different number of electrons (24 and 23 respectively).
Was this answer helpful?
0
0
Top Questions on Classification of elements and periodicity in properties
Electronic configuration, also called electronic structure, the arrangement of electrons in energy levels around an atomic nucleus. According to the older shell atomic model, electrons occupy several levels from the first shell nearest the nucleus, K, through the seventh shell, Q, farthest from the nucleus. Electrons have to be filled in the s, p, d, f in accordance with the following rule.For example, the electron configuration of sodium is 1s22s22p63s1.
Writing Electron Configurations:
Maximum number of electrons that can be accommodated in a shell is based on the principal quantum number (n). It is represented by the formula 2n2, where ‘n’ is the shell number.
Filling of Atomic Orbitals:
1. Aufbau’s principle: The filling of electrons should take place in accordance with the ascending order of energy of orbitals:
Lower energy orbital should be filled first and higher energy levels.
The energy of orbital α(p + l) value it two orbitals have same (n + l) value, E α n
Ascending order of energy 1s, 2s, 2p, 3s, 3p, 4s, 3d, . . .
2. Pauli’s exclusion principle: No two electrons can have all the four quantum numbers to be the same or if two electrons have to be placed in an energy state they should be placed with opposite spies.
3. Hund’s rule of maximum multiplicity: In the case of filling degenerate (same energy) orbitals, all the degenerate orbitals have to be singly filled first and then only pairing has to happen.
