Question

write the unabbreviated electron configurations or noble gas configurations of the following elements:

1. copper
2. magnesium
3. potassium
4. barium
5. zirconium

the following electron configurations belong to which elements:

1. 1s² 2s² 2p⁶ 3s¹
2. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰4p⁶ 5s² 4d⁶
3. kr 5s² 4d¹⁰
4. xe 6s² 4f¹⁴5d¹⁰6p²
5. rn 7s² 5f¹⁴6d⁴

Explanation:

Step1: For writing electron configurations

• Copper (Cu): It has 29 electrons. The normal filling would be \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{9}\), but due to the stability of a half - filled or completely filled \(d\) - subshell, one electron from the \(4s\) - subshell moves to the \(3d\) - subshell. So the configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{10}\).
• Magnesium (Mg): It has 12 electrons. Using the Aufbau principle, the configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}\).
• Potassium (K): It has 19 electrons. The configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}\).
• Barium (Ba): It has 56 electrons. The noble - gas configuration (using Xe as the previous noble gas, which has 54 electrons) is \([Xe]6s^{2}\).
• Zirconium (Zr): It has 40 electrons. The noble - gas configuration (using Kr as the previous noble gas, which has 36 electrons) is \([Kr]5s^{2}4d^{2}\).

Step2: For identifying elements from electron configurations

• \(1s^{2}2s^{2}2p^{6}3s^{1}\): Count the electrons: \(2 + 2+6 + 1=11\). The element with 11 electrons is sodium (Na).
• \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{6}\): Count the electrons: \(2+2 + 6+2+6+2+10+6+2+6 = 44\). The element with 44 electrons is ruthenium (Ru).
• \([Kr]5s^{2}4d^{10}\): Kr has 36 electrons. Adding \(2 + 10=12\) more electrons. \(36+12 = 48\). The element with 48 electrons is cadmium (Cd).
• \([Xe]6s^{2}4f^{14}5d^{10}6p^{2}\): Xe has 54 electrons. Adding \(2+14 + 10+2=28\) more electrons. \(54+28 = 82\). The element with 82 electrons is lead (Pb).
• \([Rn]7s^{2}5f^{14}6d^{4}\): Rn has 86 electrons. Adding \(2+14 + 4=20\) more electrons. \(86+20 = 106\). The element with 106 electrons is seaborgium (Sg).

Answer:

1. \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{10}\)
2. \(1s^{2}2s^{2}2p^{6}3s^{2}\)
3. \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}\)
4. \([Xe]6s^{2}\)
5. \([Kr]5s^{2}4d^{2}\)
6. Sodium (Na)
7. Ruthenium (Ru)
8. Cadmium (Cd)
9. Lead (Pb)
10. Seaborgium (Sg)