Question

determine which of the following elements electron configurations are not correct. if it is incorrect, explain what it is and correct the mistake. if it is correct, write correct.

1. i: 1s²2s²2p⁶3s²3p⁶4s²4d¹⁰4p⁵
2. cl: 1s²2s²2p⁶3s²3d⁵
3. pd: rb 5s²4d⁸
4. xe: kr 5s²4d¹⁰5p⁵

Explanation:

Step1: Analyze the electron configuration of I

The atomic number of I is 53. The noble - gas core is \([Kr]\) (atomic number 36). The remaining electrons are \(53 - 36=17\). The electron configuration should be \([Kr]4d^{10}5s^{2}5p^{5}\). The given configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}4d^{10}4p^{5}\) is wrong because after \(4p\) comes \(5s\) and then \(4d\) (based on the Aufbau principle: \(n + l\) rule. For \(4p\): \(n + l=4 + 1 = 5\), for \(5s\): \(n + l=5+0 = 5\), but \(5s\) has lower energy than \(4d\) when filling electrons. The correct order is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{5}\)

Step2: Analyze the electron configuration of Cl

The atomic number of Cl is 17. The electron configuration should be \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}\). The given configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3d^{5}\) is wrong. After \(3s\), we fill \(3p\) orbitals (Aufbau principle: \(n + l\) for \(3s\) is \(3 + 0=3\), for \(3p\) is \(3+1 = 4\), for \(3d\) is \(3 + 2=5\). We fill orbitals in the order of increasing \(n + l\) value. So, \(3s\) is filled first, then \(3p\), and then \(3d\)

Step3: Analyze the electron configuration of Pd

The atomic number of Pd is 46. The noble - gas core \([Kr]\) (36 electrons). The remaining \(46-36 = 10\) electrons. The electron configuration of Pd is \([Kr]4d^{10}\) (due to the stability of the fully - filled \(d\) - subshell). The given configuration \([Rb]5s^{2}4d^{8}\) is wrong. \([Rb]\) has 37 electrons. Also, according to the Aufbau principle and electron - pairing rules, for Pd, the \(4d\) subshell is fully - filled (\(4d^{10}\)) rather than having \(5s^{2}4d^{8}\)

Step4: Analyze the electron configuration of Xe

The atomic number of Xe is 54. The noble - gas core \([Kr]\) (36 electrons). The remaining \(54 - 36=18\) electrons. The electron configuration is \([Kr]4d^{10}5s^{2}5p^{6}\). The given configuration \([Kr]5s^{2}4d^{10}5p^{5}\) is wrong as it should have \(5p^{6}\) (a fully - filled \(p\) - subshell for the noble gas Xe)

Answer:

• For \(I\): The given configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}4d^{10}4p^{5}\) is incorrect. The correct configuration is \([Kr]4d^{10}5s^{2}5p^{5}\) (or expanded \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{5}\)) because of the Aufbau principle (order of filling \(n + l\) rule)
• For \(Cl\): The given configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3d^{5}\) is incorrect. The correct configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}\) as \(3p\) orbitals should be filled before \(3d\) (Aufbau principle)
• For \(Pd\): The given configuration \([Rb]5s^{2}4d^{8}\) is incorrect. The correct configuration is \([Kr]4d^{10}\) due to the stability of the fully - filled \(d\) - subshell
• For \(Xe\): The given configuration \([Kr]5s^{2}4d^{10}5p^{5}\) is incorrect. The correct configuration is \([Kr]4d^{10}5s^{2}5p^{6}\) (a noble gas with a fully - filled \(p\) - subshell)