Here are the solutions to the problems on the worksheet.
Write the electron configurations of the following elements:
3)
Potassium (K): Atomic number 19.
$1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$
4)
Bismuth (Bi): Atomic number 83.
$1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10} 6p^3$
5)
Zirconium (Zr): Atomic number 40.
$1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^2$
Write the abbreviated electron configurations of the following elements:
6)
Indium (In): Atomic number 49. Previous noble gas is Krypton [Kr] (36).
$[Kr] 5s^2 4d^{10} 5p^1$
7)
Chlorine (Cl): Atomic number 17. Previous noble gas is Neon [Ne] (10).
$[Ne] 3s^2 3p^5$
8)
Molybdenum (Mo): Atomic number 42. Previous noble gas is Krypton [Kr] (36). *Note: This is an exception where an s-electron moves to the d-orbital.*
$[Kr] 5s^1 4d^5$
9)
Caesium (Cs): Atomic number 55. Previous noble gas is Xenon [Xe] (54).
$[Xe] 6s^1$
10)
Magnesium (Mg): Atomic number 12. Previous noble gas is Neon [Ne] (10).
$[Ne] 3s^2$
The following electron configurations belong to which elements:
11) $1s^2 2s^2 2p^4$: Total electrons = 8. Element is
Oxygen (O).
12) $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6$: Total electrons = 26. Element is
Iron (Fe).
13) $[Kr] 5s^2 4d^2$: Krypton (36) + 4 electrons = 40. Element is
Zirconium (Zr).
14) $[Ar] 4s^2 3d^{10} 4p^3$: Argon (18) + 15 electrons = 33. Element is
Arsenic (As).
15) $[Rn] 7s^2 5f^8$: Radon (86) + 10 electrons = 96. Element is
Curium (Cm).
Determine if the following electron configurations are correct:
16) $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 4d^{10} 4p^6 5s^1$:
Incorrect. The $4d$ subshell fills after the $5s$ subshell, not before. Also, the order listed skips $3d$. The correct configuration for this number of electrons (Silver, Ag) is $[Kr] 5s^1 4d^{10}$.
17) $1s^2 2s^2 2p^6 3s^1$:
Correct. This is Sodium (Na).
18) $[Kr] 7s^2 5f^8 6d^4$:
Incorrect. After Radon ($[Rn]$), electrons fill $7s$, then $5f$, then $6d$. Using $[Kr]$ as a base here leaves too many electrons and mixes shells incorrectly. The element with this many electrons would be based on Radon, not Krypton.
19) $[Ar] 5s^2 4d^{10} 5p^3$:
Incorrect. After Argon ($[Ar]$), you must fill the $3d$ and $4p$ orbitals (which makes Krypton) before moving to the 5th energy level.
20) $[Xe] 6s^2 4f^{14}$:
Correct. This is Ytterbium (Yb).
Final Answer:
3) $1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$
4) $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10} 6p^3$
5) $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^2$
6) $[Kr] 5s^2 4d^{10} 5p^1$
7) $[Ne] 3s^2 3p^5$
8) $[Kr] 5s^1 4d^5$
9) $[Xe] 6s^1$
10) $[Ne] 3s^2$
11) Oxygen
12) Iron
13) Zirconium
14) Arsenic
15) Curium
16) Incorrect
17) Correct
18) Incorrect
19) Incorrect
20) Correct
Parent Tip: Review the logic above to help your child master the concept of electron configurations worksheet answers.
