Question

1. practice: determine the electron configurations of the following elements. use the gizmo to check your work. (note: in some cases, the diagonal rule doesnt work perfectly. if you submit a theoretically correct configuration, the gizmo will give you the actual configuration.)

element atomic number electron configuration
cobalt (co) 27
germanium (ge) 32
neodymium (nd) 60
gold (au) 79

1. infer: select the periodic table tab. earlier you saw that the transition metals represent the filling of the d subshells. now locate the purple lanthanides and actinides on the bottom rows of the periodic table.

a. how many elements are in the lanthanides series?
b. which subshell is represented by the lanthanides series?
c. which subshell is represented by the actinides series?
d. in general, how does the shape of the periodic table relate to electron configuration?

Explanation:

Cobalt (Co)

Step1: Fill orbitals

Start filling orbitals according to the Aufbau principle. The order of filling is \(1s < 2s<2p < 3s<3p<4s < 3d\).
For \(Z = 27\) (atomic number of Co), we have:
\(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{7}\)

Germanium (Ge)

Step1: Fill orbitals

For \(Z = 32\). After filling \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}\), we start filling \(4p\) orbitals.
The electron - configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{2}\)

Neodymium (Nd)

Step1: Fill orbitals

For \(Z = 60\). After filling \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}\), we start filling \(4f\) orbitals.
The electron - configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}4f^{4}\)

Gold (Au)

Step1: Consider electron - configuration rules

For \(Z = 79\). Due to the stability of half - filled and fully - filled orbitals. After filling \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{1}\), we have a more stable configuration with \(5d^{10}\) (instead of \(6s^{2}5d^{9}\)).
The electron - configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{1}4f^{14}5d^{10}\)

Question 10

A. Lanthanides series elements

The lanthanides series has 14 elements (from \(_{58}\text{Ce}\) to \(_{71}\text{Lu}\))

B. Subshell for lanthanides

The lanthanides series represents the filling of the \(4f\) subshell

C. Subshell for actinides

The actinides series represents the filling of the \(5f\) subshell

D. Periodic table and electron - configuration

The shape of the periodic table is related to electron - configuration. The rows (periods) correspond to the principal quantum number \(n\) of the outermost occupied shell. The columns (groups) are related to the type of subshell (\(s\), \(p\), \(d\), \(f\)) and the number of electrons in the subshell. For example, the \(s\) - block elements (Groups 1 and 2) have their outermost electrons in \(s\) orbitals, the \(p\) - block elements (Groups 13 - 18) have their outermost electrons in \(p\) orbitals, the \(d\) - block elements (transition metals) have their outermost electrons in \(d\) orbitals (along with \(s\) orbitals in lower periods), and the \(f\) - block elements (lanthanides and actinides) have their outermost electrons in \(f\) orbitals (along with \(s\) and \(d\) orbitals in lower periods)

Answer:

• Cobalt (Co): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{7}\)
• Germanium (Ge): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{2}\)
• Neodymium (Nd): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}4f^{4}\)
• Gold (Au): \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{1}4f^{14}5d^{10}\)
• 10A: 14
• 10B: \(4f\)
• 10C: \(5f\)
• 10D: The rows (periods) correspond to the principal quantum number \(n\) of the outermost occupied shell. The columns (groups) are related to the type of subshell (\(s\), \(p\), \(d\), \(f\)) and the number of electrons in the subshell.