General Chemistry - Quantum Mechanical Model and Light

Vocabulary flashcards generated from General Chemistry lecture notes on atomic theory, light equations, photoelectric effect, wave mechanics, and quantum numbers.

Quantum mechanical model

Modern model of the atom that describes electrons using probability rather than definite paths.

Electromagnetic radiation

A type of energy consisting of electric and magnetic fields that oscillate perpendicular to each other and travel through a vacuum at $C = 3.00 \times 10^8 proposal m/s$.

Wavelength

The distance from one wave crest to the next, represented in meters ($\text{m}$) or nanometers ($\text{nm}$), where $1\,\text{nm} = 1 \times 10^{-9}\,\text{m}$.

Frequency

The number of wave cycles passing a point per second, with units of Hertz ($\text{Hz} = \text{s}^{-1}$) or cycles.

Amplitude

The height of a wave; a larger amplitude indicates greater total energy or intensity.

Wave equation

$C = \lambda \nu$, showing that wavelength ($\lambda$) and frequency ($\nu$) are inversely proportional.

Electromagnetic spectrum

The spectrum of light waves ordered from high frequency, high energy, and shorter wavelength (gamma ray, x-ray, ultraviolet) to low frequency, lower energy, and longer wavelength (infrared, microwave, radio).

Constructive interference

Occurs when waves are in phase, reinforcing each other to produce a larger wave.

Destructive interference

Occurs when waves are out of phase, canceling each other out to form a smaller or zero wave.

Diffraction

The bending or spreading of waves around an obstacle or through a slit.

Photoelectric effect

A phenomenon demonstrating that light behaves like particles (photons), where photon energy is given by $E = h\nu$.

Planck's constant

A fundamental constant ($h$) equal to $h = 6.626 \times 10^{-34}\,\text{J}\cdot\text{s}$.

Photoelectric effect equation

$KE = h\nu - \phi$ (or $KE = E_{\text{photon}} - E_{\text{binding}}$), where $KE$ is the kinetic energy of the emitted electron, $h\nu$ is the incoming photon energy, and $\phi$ is the binding energy or work function.

Threshold frequency

The minimum frequency of light required to eject an electron from a material.

Bohr model

Atomic model establishing that electrons occupy allowed energy states rather than arbitrary energies, gaining energy during absorption and releasing energy as a photon during emission.

Nodes

Regions where the probability of finding an electron is zero, given by $n - 1$ for a principal level $n$.

Probability density

Represented by $\psi^2$, it indicates the likelihood of finding an electron at a particular location.

Radial distribution function

A function that describes the probability of finding an electron at a particular distance from the nucleus.

de Broglie equation

$\lambda = \frac{h}{m v}$, relating the wavelength ($\lambda$) of a particle to Planck's constant ($h$), mass ($m$ in $\text{kg}$), and velocity ($v$ in $\text{m/s}$).

Heisenberg uncertainty principle equation

$\Delta x (m \Delta v) = \frac{h}{4\pi}$, where $\Delta x$ is uncertainty in position, $m$ is mass, $\Delta v$ is uncertainty in velocity, and $h$ is Planck's constant.

Orbital

A three-dimensional region around the nucleus where an electron is likely to be found.

Principal quantum number

Designated as $n$ ($n = 1, 2, 3, 4\dots$), it specifies the main energy level and general size of an orbital.

Angular momentum quantum number

Designated as $l$ ($l = 0$ to $n - 1$), it specifies the sublevel and shape of an orbital.

Magnetic quantum number

Designated as $m_l$ ($m_l = -l \dots 0 \dots +l$), it specifies the 3D orientation of an orbital in space.

Spin quantum number

Designated as $m_s$, it specifies the electron spin direction with values of $m_s = +\frac{1}{2}$ or $m_s = -\frac{1}{2}$.

s sublevel

Sublevel corresponding to $l = 0$ with a spherical shape, containing 1 orbital and holding a maximum of 2 electrons.

p sublevel

Sublevel corresponding to $l = 1$ with a dumbbell shape, containing 3 orbitals ($m_l = -1, 0, 1$) and holding a maximum of 6 electrons.

d sublevel

Sublevel corresponding to $l = 2$ with a clover-like shape, containing 5 orbitals and holding a maximum of 10 electrons.

f sublevel

Sublevel corresponding to $l = 3$ with a complex shape, containing 7 orbitals and holding a maximum of 14 electrons.