Quantum Theory
What does the Heisenberg Uncertainty Principle tell us?
We cannot simultaneously know the exact position and exact momentum of an electron.
Write the ground-state electron configuration for oxygen.
1s² 2s² 2p⁴
As you move left → right across a period, atomic radius generally
Decreases
An electron is in a 4f orbital.
What are the possible values of n, ℓ, and mℓ?
n = 4
ℓ = 3
mℓ = −3, −2, −1, 0, +1, +2, +3
How many unpaired electrons are present in a ground-state nitrogen atom?
3
Which has the larger atomic radius: Na or Cl?
Explain why.
Na.
Both are in Period 3, but Cl has a greater effective nuclear charge, pulling its electrons closer to the nucleus
Which set of quantum numbers is NOT possible?
A. n = 3, ℓ = 2, mℓ = −1
B. n = 2, ℓ = 1, mℓ = 0
C. n = 4, ℓ = 3, mℓ = +2
D. n = 3, ℓ = 3, mℓ = 0
D. n = 3, ℓ = 3, mℓ = 0
Write the shorthand electron configuration for Cr and Cu.
Cr: [Ar] 4s¹ 3d⁵
Cu: [Ar] 4s¹ 3d¹⁰
Which element has the higher first ionization energy: Mg or Al?
Why?
Mg.
Although IE generally increases across the period, Al's first electron removed is from a higher-energy 3p orbital, making it easier to remove than Mg's 3s electron.