1.2.3 Electronic Configuration

• What does electronic configuration describe?

  Arrangement of electrons
• What is the maximum number of electrons in the first shell?

  2
• Arrange the following subshells in the order they are filled according to the Aufbau principle:

  1️⃣ 1s

  2️⃣ 2s

  3️⃣ 2p

  4️⃣ 3s

  5️⃣ 3p

  6️⃣ 4s

  7️⃣ 3d
• The electronic configuration of sodium (Na) is 1s² 2s² 2p⁶ 3s¹.

  True
• When filling the 2p orbitals, electrons will first pair up in the 2px orbital according to Hund's rule.

  False
• The Aufbau principle states that electrons minimize pairing in degenerate orbitals.

  False
• How many electrons can the first shell hold?

  2
• What does the Pauli exclusion principle state?

  No identical quantum numbers
• What is the order in which electrons fill energy levels according to the Aufbau principle?

  1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s
• Match the subshell with its maximum number of electrons:

  s ↔️ 2

  p ↔️ 6

  d ↔️ 10

  f ↔️ 14
• The Aufbau principle states that electrons occupy the lowest available energy
• The second shell can hold a maximum of 8 electrons.
• How many electrons can the 1s subshell hold?

  2
• What is the main idea of Hund's rule?

  Maximize spin multiplicity
• What does Hund's rule state when filling degenerate orbitals?

  Maximize spin multiplicity
• What does the Aufbau principle state?

  Fill lowest energy levels
• Arrange the order in which electrons fill subshells according to the Aufbau principle:

  1️⃣ 1s

  2️⃣ 2s

  3️⃣ 2p

  4️⃣ 3s

  5️⃣ 3p

  6️⃣ 4s

  7️⃣ 3d
• The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers
• When writing electronic configurations, electrons fill subshells in order of increasing energy.


  True
• Hund's rule states that electrons in degenerate orbitals should pair up immediately to minimize spin multiplicity.

  False
• The Aufbau principle is based on the idea that electrons are added to orbitals in order of increasing energy.


  True
• The electronic configuration of sodium (Na) is 2, 8, 1.


  True
• The electron configuration of oxygen (O) is 1s^2 2s^2 2p^4.


  True
• Order the subshells according to increasing energy levels.

  1️⃣ 1s

  2️⃣ 2s

  3️⃣ 2p

  4️⃣ 3s

  5️⃣ 3p

  6️⃣ 4s

  7️⃣ 3d
• Hund's rule minimizes the pairing
• Match the concept with its description:

  Pauli exclusion principle ↔️ No two electrons in an atom can have the same four quantum numbers

  Quantum numbers ↔️ Describe the state of an electron in an atom

  Quantum state ↔️ Complete set of quantum numbers for an electron
• The Pauli exclusion principle states that no two electrons can have the same four quantum numbers.
• What is the shorthand notation for argon (Ar)?

  [Ne] 3s^2 3p^6
• The Pauli exclusion principle states that two electrons in the same atom can have the same set of quantum numbers.

  False
• The Aufbau principle dictates that electrons first fill the 1s subshell before the 2s subshell.


  True
• The 3d subshell can hold a maximum of 10 electrons.
• Hund's rule contrasts with the Aufbau principle by emphasizing the pairing of electrons in degenerate orbitals.
• Hund's rule states that electrons will maximize the multiplicity of the spin
• Match the atomic concept with its description:

  Electronic Configuration ↔️ Arrangement of electrons in shells

  Energy Levels ↔️ Regions around the nucleus

  Nucleus ↔️ Central part of the atom
• The electronic configuration of oxygen (O) is 1s^2 2s^2 2p^4.


  True
• Why do the two electrons in helium satisfy the Pauli exclusion principle?

  Different spin quantum numbers
• Match the rule with its guideline when writing electronic configurations:

  Aufbau principle ↔️ Fill lowest energy levels first

  Hund's rule ↔️ Maximize spin multiplicity

  Pauli exclusion principle ↔️ No identical quantum numbers
• The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers
• According to Hund's rule, electrons in degenerate orbitals should maximize their spin
• Steps to write the electronic configuration for sodium (Na) with 11 electrons:

  1️⃣ Start with the 1s orbital, which can hold 2 electrons. The configuration is 1s^2.

  2️⃣ Move to the 2s orbital, which can hold 2 more electrons. The configuration is now 1s^2 2s^2.

  3️⃣ Next, fill the 2p orbitals, which can hold 6 electrons. The configuration becomes 1s^2 2s^2 2p^6.

  4️⃣ Finally, fill the 3s orbital, which can hold 1 more electron. The complete electronic configuration for sodium is 1s^2 2s^2 2p^6 3s^1.