Quantum Numbers and Atomic Structure Practice Flashcards

Practice vocabulary flashcards based on lecture notes covering atomic models, quantum numbers, electron filling rules, and early periodic classification.

Principal Quantum Number

Represented by $n$, it specifies the shell of an electron.

Azimuthal Quantum Number

Represented by $l$, it defines the sub-shell and its shape, with values ranging from $0$ to $n - 1$.

Magnetic Quantum Number

Represented by $m$, it tells about the orientation of the orbital and depends on the azimuthal quantum number.

Spin Quantum Number

Represented by $s$, it indicates the spin of the electron, which can be clockwise ($+\frac{1}{2}$) or anti-clockwise ($-\frac{1}{2}$).

s-shell

The sub-shell where $l = 0$, named 'sharp' and characterized by a spherical shape.

p-shell

The sub-shell where $l = 1$, named 'principal' and characterized by a dumbbell shape.

d-shell

The sub-shell where $l = 2$, named 'diffused' and characterized by a double-dumbell shape.

f-shell

The sub-shell where $l = 3$, named 'fundamental' and characterized by a complex shape.

Number of subshells in the $n^{th}$ shell

$$n$$

Number of orbitals in the $l^{th}$ sub-shell

$$2l + 1$$

Number of orbitals in the $n^{th}$ shell

$$n^2$$

De-generated orbitals

Orbitals having the same $n$ and $l$ values but different values of $m$, resulting in the same energy level in the absence of external electric or magnetic fields.

Pauli's Exclusion Principle

The principle stating that no two electrons in an atom can have the same set of all four quantum numbers.

Aufbau's Principle

The filling of electrons in subshells according to the increasing order of their energy levels.

(n+l) Rule

A rule stating that the higher the value of $(n+l)$, the higher the energy of the subshell; if values are equal, the lower $n$ value indicates lower energy.

Hund's Rule of Spin Multiplicity

A rule stating that electrons occupy orbitals of equal energy singly with parallel spins first before pairing begins to achieve maximum stability.

Monoelectronic species

Also called Bohr species, these are species like $H$, $He^+$, or $Li^{2+}$ that contain only one electron and have degenerate subshells for the same $n$ value.

Exchange energy

Energy released when electrons with parallel spin in degenerate orbitals exchange their positions, providing extra stability.

Effective Nuclear Charge ($Z_{eff}$)

The actual nuclear charge experienced by an electron, calculated as $Z_{eff} = Z - \sigma$.

Slater's Rule

A method used to calculate the shielding or screening constant ($\sigma$) to determine the effective nuclear charge.

Lavoisier Classification

An early classification system dividing elements into metals (which tend to lose electrons) and non-metals (which tend to gain electrons).

Dobereiner Law of Triads

A system where elements are arranged in groups of three, such that the atomic mass of the middle element is roughly the average of the first and third.

Newland's Law of Octaves

The observation that when elements are arranged by increasing atomic mass, every eighth element shows similar properties to the first.