Holt McDougal Chemistry Chapter 4

Waves and Particles

Light has characteristics of these two things.

Electromagnetic Radiation

A form of energy that exhibits wavelike behavior as it travels through space.

Electromagnetic Spectrum

All the forms of electromagnetic radiation.

Same

Do the forms of electromagnetic radiation move at the same speed or a different speed through a vacuum?

Wavelength

The distance between corresponding points on adjacent waves.

Frequency

The number of waves that pass a given point in a specific time, usually one second.

Hertz

Unit used to express frequency.

Inversely Proportional

Wavelength and Frequency are _____________ ____________.

Photoelectric Effect

Refers to the emission of electrons from a metal when light shines on the metal.

Frequency

Light’s ____________ needs to reach a certain minimum in order to emit electrons from a certain metal.

Max Planck

German physicist who explained the photoelectric effect after studying the emission of electrons by hot objects.

Quantum

The minimum quantity of energy that can be lost or gained from an atom.

Albert Einstein

German physicist who suggested that electromagnetic radiation had a dual wave-particle nature, and that it is absorbed by matter in only whole numbers of photons.

Photon

Particle of electromagnetic radiation having zero mass and carrying a quantum of energy.

Ground State

The lowest energy state of an atom; only one for atoms of a given element.

Excited State

A state in which an atom has a higher potential energy than it has in its ground state; there are many possible, each with a unique energy.

Released

Energy is ___________ in the form of electromagnetic radiation when an atom returns to a ground state or a lower energy state from an excited state.

Emission-Line Spectrum

When a narrow beam of emitted light is shined through a prism, it is separated into specific colors of the visible spectrum; these bands of light make up an element’s [this].

Continuous Spectrum

The emission of a continuous range of frequencies of electromagnetic radiation.

Quantum Theory

Atomic theory that attempted to explain why the hydrogen atoms only gave off specific frequencies of light.

Equal

The energy of the photon released is _________ to the difference in energy between the atom’s initial state and its final state.

Orbits

Paths that the electron can circle the nucleus on as part of Bohr’s model of the hydrogen atom.

Increases

The energy of an electron ___________ as it moves farther away from the nucleus.

Gaining

An electron can move to a higher-energy orbit by __________ an amount of energy equal to the difference in energy between the desired and initial orbit.

Emission

Process by which an electron falls to a lower energy level and releases a photon.

Absorption

Process by which energy is added to an atom in order to move an electron from a lower energy level to a higher energy level.

Louis de Broglie

Scientist who suggested that electrons have a dual wave-particle nature; suggested that electrons be considered waves confined to the space around an atomic nucleus.

Diffraction

The bending of a wave as it passes by the edge of an object or through a small opening.

Interference

Occurs when waves overlap, resulting in a reduction of energy in same areas and an increase in energy in others.

Heisenberg Uncertainty Principle

States that it is impossible to determine simultaneously both the position and velocity of an electron or any other particle.

Erwin Schrödinger

Used the hypothesis that electrons have a dual wave-particle nature to develop an equation that treated electrons in atoms as waves; quantization of electron energies was a natural outcome of said equation.

Quantum Theory

Describes mathematically the wave properties of electrons and other very small particles.

Wave Functions

Solutions to the Schrödinger wave equation.

Orbital

A three-dimensional region around the nucleus that indicates the probable location of an electron.

Quantum Numbers

Specify the properties of atomic orbitals and the properties of electrons in orbitals.

Principal Quantum Number

Symbolized by n, indicates the main energy level occupied by the electron. Values of n are positive integers only.

Increases

As n increases, the electron’s energy and its average distance from the nucleus ____________.

Angular Momentum Quantum Number

Symbolized by l, and indicates the shape of the orbital. The values of l allowed are 0 and all positive integers less than or equal to n-1.

S

Spherical orbitals; l=0.

P

Dumbbell-shaped orbitals; l=1.

D

Complex orbitals; l=2.

F

More complex orbitals; l=3.

N

In the nth main energy level, there are __ sublevels.

Magnetic Quantum Number

Symbolized by m, and indicates the orientation of an orbital around the nucleus. The m values are whole numbers (including 0) from -l to +l.

Spin Quantum Number

Has only two possible values—+1/2 and -1/2—which indicate the two fundamental spin states of an electron in an orbital.

Electron Configuration

The arrangement of electrons in an atom.

Ground State Electron Configuration

The lowest-energy arrangement of the electrons for each element.

Aufbau Principle

An electron occupies the lowest-energy orbital that can receive it.

Pauli Exclusion Principle

No two electrons in the same atom can have the same set of four quantum numbers.

Hund’s Rule

Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin state.

Highest-Occupied Energy Level

The electron-containing main energy level with the highest principle quantum number

Inner-Shell Electrons

Electrons that are not in the highest-occupied energy level.

Octet

Atoms which have the s and p sublevels of their highest-occupied energy level are said to have an _______ of electrons.

Noble Gases

The elements in Group 18; includes Helium, Neon, Argon, Krypton, Xenon, and Radon

Noble Gas Configuration

Refers to an outer main energy level occupied, in most cases, by eight electrons.