Chapter 7.4: The Quantum-Mechanical Model of the Atom

Flashcards from Chapter 7.4 of Chemistry: The Molecular Nature of Matter and Change.

Quantum mechanics

A field that examines the wave nature of objects on the atomic scale

Atomic orbital

An equation that models the electron’s likely position in terms of time and position around the nucleus

Electron density diagram

A representation of an energy sublevel as the probability of finding the electron within a volume as a function of the distance from the nucleus

Principal quantum number (n)

A number that indicates the relative size of the orbital, specifying the atom’s energy level

• A ground-state H electron has n = 1

• n² gives the total number of orbitals present

Angular momentum quantum number (l)

A number that ranges from [0, n - 1], giving the atom’s sublevel identifier and shape for a given n and l

• l = 0 is designated as s

• l = 1 is designated as p

• l = 2 is designated as d

• l = 3 is designated as f

For example, a sublevel with n = 2, l = 0 is given 2s designation

Magnetic quantum number (m_l)

A number that ranges from [-l, l], giving the number, orientation, and identifier of orbitals for a given l

• For example, l = 3 gives [-3, -2, -1, 0, 1, 2, 3] for 7 total orbitals

Spin quantum number (m_s)

A number describing the spin of an electron going clockwise or counterclockwise, with values of {±1/2}

s orbital

An orbital with l = 0 and a spherical shape and an m_l = 0, with highest probabilities increasing farther from the nucleus with greater values of n

p orbital

An orbital with l = 1 with two regions of high probability on either side of the nucleus, divided by the nodal plane

• Electrons spend equal time in both lobes

• Differ in orientation across different m_l values from ±1

d orbital

An orbital with l = 2 with four regions of high probability and m_l values ranging between ±2 for five orientations

f orbital

An orbital with l = 3, n ≥ 4, and m_l in the range ±3 for seven orientations