Key Terms for Chapter 8 The Quantum-Mechanical Model of the Atom

St. Catherine General Chemistry I

Quantum-Mechanical Model

Explains the manner in which electrons exist and behave in atoms

Electromagnetic spectrum

All wavelengths of electromagnetic radiation

Electromagnetic radiation

form of energy embodied in oscillating electric and magnetic field

Amplitude

vertical height of the crest of a wave

intensity

Amplitude determines light’s

wavelength

distance between adjacent crests

frequency

the # of cycles (or wave crests) that pss through a stationary point in a given period of time, s^-1 or 1 cycle/s = Hz

inversely

Frequency is ______ related to wavelength

10^-9

nano

Interference

Waves can cancel each other out or build each other up

Constructive interference

waves of equal amplitude are in phase (align with overlapping crests)

Destructive Interference

waves of are out of phase (align so troughs and crests overlap)

Diffraction

When a wave encounters an obstacle or slit comparable in size to its wavelength, it bends (diffracts) around it. Light passing through 2 slits of light comparable to its wavelength results in an interference pattern. Waves act as a new wave source and the two new waves interfere with each other

Photon

A “particle” (or packet) of light

higher

The shorter the wavelength, the _______ the frequency of that wave

higher

The higher the frequency of a wave, the ______ the energy of the photon with that frequency

quantized

Electron energies in atoms are ______ (only specific energies are allowed)

Photoelectric effect

observation that many metals emit electrons when light shines upon them

packets

light energy must come in ______

directly proportional, inversely proportional

The energy of a photon is ______ to its frequency and _______ to its wavelength

Continuously

All matter _____ absorbs/emits EMR

Classical prediction of photoelectric effect

The number and energy of emitted electrons should depend only on the intensity of light

Actual observation of photoelectric effect

The # and energy of emitted electrons depends on the frequency of light

photon

stream of particles called

Wave-particle duality

EMR is both a wave and a particle

Emission spectrum

Emitted light when molecules absorb energy, have unique wavelengths, can be used to identify the element

waves, electrons

Diffraction is a property of _____ and ______

Spectral lines

changes in energy when an electron moves from a higher “orbit” to a lower “orbit”

c

wavelength of photon

E=hv

Frequency of a photon

Uncertainty Principle

The more accurately the position of a particle is known, such as an electron, the less the velocity is known (and vice-versa)

wave functions

mathematical function that describes wavelike nature of electron