Chemistry Unit 2: Waves, Atomic Structure, and Periodic Trends

Vocabulary practice flashcards covering wave properties, electromagnetic radiation, quantum models, electron configurations, and periodic trends from Chemistry Unit 2.

Wavelength ($\lambda$)

The distance between consecutive wave peaks.

Frequency ($\nu$)

The number of wave cycles that pass a given point per second ($\text{waves/second}$ or $\text{s}^{-1}$).

Amplitude

The height of a wave measured from its centerline to its crest.

Speed of Light ($c$)

The speed of electromagnetic radiation, defined by the formula $c = \lambda \nu$ and equal to $3.00 \times 10^8\,\text{m/s}$.

Planck's Constant ($h$)

A fundamental constant relating energy to frequency in the equation $E = h\nu$, equal to $6.626 \times 10^{-34}\,\text{J}\cdot\text{s}$.

Electromagnetic Spectrum

The complete range of electromagnetic radiation ordered by decreasing wavelength and increasing frequency/energy: radio $\rightarrow$ microwave $\rightarrow$ IR $\rightarrow$ visible $\rightarrow$ UV $\rightarrow$ X-ray $\rightarrow$ Gamma.

Visible Light Spectrum

The sequence of visible colors ordered from longest wavelength to shortest: red $\rightarrow$ orange $\rightarrow$ yellow $\rightarrow$ green $\rightarrow$ blue $\rightarrow$ violet, where red has the lowest energy and violet has the highest energy.

Diffraction

A wave property described as the spreading out of plane waves as they pass through a narrow hole or opening.

Constructive Interference

Interference that occurs when two waves are "in phase," combining to produce a wave of greater amplitude.

Destructive Interference

Interference that occurs when two waves are "out of phase," canceling each other out.

Double Slit Experiment

An experiment providing evidence for the wave behavior of light through diffraction and interference patterns produced on a screen.

Photon

A discrete particle or quantum of light whose energy is determined by its frequency ($E = h\nu$).

Photoelectric Effect

The phenomenon in which light ejects electrons from a metal surface, requiring a threshold frequency regardless of light brightness, providing evidence that light behaves as a particle.

Wave-Particle Duality

The concept that light and matter (such as electrons) exhibit properties of both waves (diffraction and interference) and particles (photoelectric effect).

Continuum Spectrum

An unbroken, continuous band of all wavelengths and colors emitted by a light source without discrete dark or bright lines.

Atomic Emission Spectrum

A series of specific, discrete wavelengths or colors of light emitted when an excited electron transitions to a lower energy state ($\text{electron goes down } \rightarrow \text{ emits photon}$), characteristic of each element like a fingerprint.

Absorption Line Spectrum

A spectrum showing dark lines where specific wavelengths of light are absorbed by cold gas as electrons transition to higher energy levels ($\text{electron goes up } \rightarrow \text{ absorbs photon}$).

Quantized

Restricted to specific, discrete energy values or levels, as observed in atomic electron states.

Ground State

The lowest available energy state of an atom or electron ($n = 1$).

Excited State

A state of an atom where an electron occupies an energy level higher than its ground state after absorbing energy.

de Broglie Equation

The formula calculating the wavelength of matter, $\lambda = \frac{h}{mv}$, where $v$ represents velocity.

Heisenberg Uncertainty Principle

The principle stating that it is impossible to simultaneously measure both the position and momentum (or velocity) of a small particle, such as an electron, with absolute certainty.

Orbital

A three-dimensional region of space around the nucleus where an electron is most probable to be found.

Principal Quantum Number ($n$)

The quantum number ($n = 1, 2, 3, 4, 5, \dots$) defining the principal energy level and size of an orbital.

Angular Momentum Quantum Number ($l$)

The quantum number ($l = 0, 1, 2, \dots, (n-1)$) determining orbital shape ($s$ is spherical with $l=0$, $p$ is dumbbell/bowtie with $l=1$, $d$ is clover/two p-orbitals with $l=2$, $f$ with $l=3$).

Magnetic Quantum Number ($m_l$)

The quantum number ($m_l = -l, \dots, +l$) indicating the three-dimensional orientation of an orbital in space.

Spin Quantum Number ($m_s$)

The quantum number with values of $+\frac{1}{2}$ or $-\frac{1}{2}$ describing the intrinsic spin direction ("spin up" or "spin down") of an electron.

Aufbau Principle

The rule stating that in the ground state of an atom or ion, electrons fill subshells of the lowest available energy first before occupying higher energy subshells.

Atomic Radius

One-half of the distance between two nuclei of identical bonded atoms; increases down a column/group and decreases across a row/period.

First Ionization Energy ($\text{IE}_1$)

The energy required to remove the first electron from an atom or ion; decreases down a group and increases across a period.

Effective Nuclear Charge ($Z_{\text{eff}}$)

The net positive charge experienced by an outer valence electron, calculated as $Z_{\text{eff}} = Z - (\text{number of core } e^-)$, where inner electrons shield the valence electrons from the full nuclear charge.