Question

9 write the unabbreviated (full) electron configuration for the sulfide ion (s²⁻). which noble gas has this same configuration?

1. write the unabbreviated (full) electron configuration for a neutral atom of copper (cu). explain why this configuration is an exception to the aufbau principle

abbreviated (noble gas) electron configuration problems
1 write the abbreviated (noble gas) electron configuration for a neutral atom of lead (pb)
2 a neutral atom has the abbreviated electron configuration ar4s²3d⁶. identify the element
3 write the abbreviated (noble gas) electron configuration for the bromide ion (br⁻)

Explanation:

Step1: Determine electron - configuration of sulfide ion

Sulfur has atomic number 16. The sulfide ion ($S^{2 - }$) has 18 electrons. Using the Aufbau principle, the electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}$.

Step2: Identify the noble gas with the same configuration

The noble gas with 18 electrons is argon (Ar), which has the electron - configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}$.

Step3: Determine electron - configuration of neutral copper atom

Copper has atomic number 29. According to the Aufbau principle, we would expect the electron - configuration to be $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{9}$. However, the actual electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{10}$. This is an exception because a half - filled ($s^{1}$) and a fully - filled ($d^{10}$) sub - shell are more stable than a filled $s$ sub - shell and a partially filled $d$ sub - shell.

Step4: Abbreviated electron - configuration of lead

Lead (Pb) has atomic number 82. The nearest noble gas is xenon (Xe) with atomic number 54. The abbreviated electron - configuration is $[Xe]6s^{2}4f^{14}5d^{10}6p^{2}$.

Step5: Identify the element from abbreviated configuration

The electron - configuration $[Ar]4s^{2}3d^{8}$ has a total of 18 (from Ar) + 2 + 8=28 electrons. The element with 28 electrons is nickel (Ni).

Step6: Abbreviated electron - configuration of bromide ion

Bromine (Br) has atomic number 35. The bromide ion ($Br^{-}$) has 36 electrons. The nearest noble gas is krypton (Kr). The abbreviated electron - configuration is $[Kr]$.

Answer:

1. Electron - configuration of $S^{2 - }$: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}$; Noble gas: Ar
2. Electron - configuration of Cu: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{10}$; Exception reason: Stability of half - filled $s$ and fully - filled $d$ sub - shells
3. Abbreviated electron - configuration of Pb: $[Xe]6s^{2}4f^{14}5d^{10}6p^{2}$
4. Element with $[Ar]4s^{2}3d^{8}$ configuration: Ni
5. Abbreviated electron - configuration of $Br^{-}$: $[Kr]$