Module 1: Electronic Structure of Matter

Who proposed the Plum Pudding Model of the atom?

Joseph John Thomson

Who proposed the Nuclear Model of the atom using the gold foil experiment?

Ernest Rutherford

Who proposed the Planetary Model of the atom with electrons in fixed energy levels?

Niels Bohr

Who proposed the Solid Sphere Model of the atom?

John Dalton

Who introduced the Electron Cloud/Quantum Mechanical Model of the atom?

Erwin Schrödinger

What does the Heisenberg Uncertainty Principle state?

It is impossible to determine both the exact position and momentum of an electron at the same time.

What does the Aufbau Principle state?

Electrons fill the lowest energy orbitals first before higher ones.

What does Hund's Rule state?

Electrons fill orbitals in a sublevel one by one before pairing, and spins are opposite when paired.

What does Pauli's Exclusion Principle state?

No two electrons can have the same set of four quantum numbers; max two electrons per orbital with opposite spins.

What does the principal quantum number (n) represent?

The main energy level or shell of an electron (K, L, M, N…).

What does the angular momentum quantum number (l) describe?

The shape of the orbital (s, p, d, f).

What does the magnetic quantum number (m1) indicate?

The orientation of the orbital in space.

What does the spin quantum number (ms) describe?

The direction of electron spin: +½ (counterclockwise) or -½ (clockwise).

How many electrons can an s orbital hold?

2

How many electrons can a p sublevel hold?

6

How many electrons can a d sublevel hold?

10

How many electrons can an f sublevel hold?

14

Maximum electrons in 1st, 2nd, 3rd, and 4th energy levels?

1st = 2, 2nd = 8, 3rd = 18, 4th = 32

Electron configuration of Hydrogen 1 (H)?

1s¹

Electron configuration of Helium 2 (He)?

1s²

Electron configuration of Oxygen 8 (O)?

1s² 2s² 2p⁴

Electron configuration of Neon 10 (Ne)?

1s² 2s² 2p⁶

Electron configuration of Sodium 11 (Na)?

1s² 2s² 2p⁶ 3s¹

What happens when an electron moves from a higher to a lower energy level?

Light/energy is released.

What is the region around the nucleus where electrons are most likely found?

Electron cloud (atomic orbital).

What does "quantization of energy" mean?

Electrons can only occupy specific energy levels, not in between.

What is the maximum number of orbitals in the 3rd energy level?

9 orbitals

What is the maximum number of electrons in the 3rd energy level?

18 electrons

What does the flame test show?

Different elements emit characteristic colors due to excited electrons releasing energy.

What subatomic particles are inside the nucleus?

Protons and neutrons

What is electron configuration used to determine?

Period number, group number, valence electrons, paired/unpaired electrons.

What are the quantum number values for the s orbital?

l = 0, m1 = 0, maximum 2 electrons

What are the quantum number values for the p orbital?

l = 1, m₁ = -1, 0, +1, maximum 6 electrons

What are the quantum number values for the d orbital?

l = 2, m₁ = -2, -1, 0, +1, +2, maximum 10 electrons

What are the quantum number values for the f orbital?

l = 3, m₁ = -3, -2, -1, 0, +1, +2, +3, maximum 14 electrons