Question

1. give the noble gas electron configuration for thallium, element 81, using orbital (box) diagrams. don’t forget the f subshell.

Explanation:

Step1: Identify the nearest noble gas

The nearest noble gas to thallium (atomic number 81) with a lower atomic number is xenon (atomic number 54). So we start with [Xe].

Step2: Determine the remaining electrons

81 - 54 = 27 remaining electrons to account for.

Step3: Fill the orbitals

The next orbitals are 6s, 4f, 5d and 6p. The 6s orbital fills first and can hold 2 electrons. Then the 4f orbital which can hold 14 electrons. After that, the 5d orbital which can hold 10 electrons and finally the 6p orbital.

• 6s: 2 electrons
• 4f: 14 electrons
• 5d: 10 electrons
• We have used 2 + 14+ 10 = 26 electrons so far. The last electron goes into the 6p orbital.

The noble - gas electron configuration in orbital - box form is [Xe] 6s$^2$ 4f$^{14}$ 5d$^{10}$ 6p$^1$. In box - diagram form:
[Xe] $\boxed{\uparrow\downarrow}$ (6s) $\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}$ (4f) $\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}\boxed{\uparrow\downarrow}$ (5d) $\boxed{\uparrow}$ (6p)

Answer:

[Xe] 6s$^2$ 4f$^{14}$ 5d$^{10}$ 6p$^1$ with orbital - box representation as described above.