Question

electron configuration
objectives:
draw an orbital diagram for a given element using up and down arrows to represent spin.
write an electron configuration for a given element.
a. draw the orbital diagrams for the following ions. this will be the same orbital diagrams as a neutral atom except youve added or subtracted some arrows to represent the electrons that were added or subtracted.
na1+
ca2+
o2-
b. write the electron configuration for the following ions.

1. be2+
2. li1+
3. f1-
4. br1-
5. mg2+
6. cl1-
7. k+
8. fe2+

Explanation:

Step1: Determine the number of electrons in each ion

• For \(Be^{2 +}\): Beryllium has an atomic number of \(4\). \(Be^{2+}\) has \(4 - 2=2\) electrons.
• For \(Li^{1+}\): Lithium has an atomic number of \(3\). \(Li^{1+}\) has \(3 - 1 = 2\) electrons.
• For \(F^{1-}\): Fluorine has an atomic number of \(9\). \(F^{1-}\) has \(9+1 = 10\) electrons.
• For \(Br^{1-}\): Bromine has an atomic number of \(35\). \(Br^{1-}\) has \(35 + 1=36\) electrons.
• For \(Mg^{2+}\): Magnesium has an atomic number of \(12\). \(Mg^{2+}\) has \(12- 2=10\) electrons.
• For \(Cl^{1-}\): Chlorine has an atomic number of \(17\). \(Cl^{1-}\) has \(17+1 = 18\) electrons.
• For \(K^{+}\): Potassium has an atomic number of \(19\). \(K^{+}\) has \(19 - 1=18\) electrons.
• For \(Fe^{2+}\): Iron has an atomic number of \(26\). \(Fe^{2+}\) has \(26-2 = 24\) electrons.

Step2: Write the electron configuration using the Aufbau principle

• \(Be^{2+}\): \(1s^{2}\)
• \(Li^{1+}\): \(1s^{2}\)
• \(F^{1-}\): \(1s^{2}2s^{2}2p^{6}\)
• \(Br^{1-}\): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}\)
• \(Mg^{2+}\): \(1s^{2}2s^{2}2p^{6}\)
• \(Cl^{1-}\): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\)
• \(K^{+}\): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\)
• \(Fe^{2+}\): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{0}3d^{6}\) (Electrons are removed from the \(4s\) orbital first as per the rule for transition - metal cations)

Answer:

1. \(Be^{2+}\): \(1s^{2}\)
2. \(Li^{1+}\): \(1s^{2}\)
3. \(F^{1-}\): \(1s^{2}2s^{2}2p^{6}\)
4. \(Br^{1-}\): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}\)
5. \(Mg^{2+}\): \(1s^{2}2s^{2}2p^{6}\)
6. \(Cl^{1-}\): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\)
7. \(K^{+}\): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\)
8. \(Fe^{2+}\): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{6}\)