Modern Chemistry HMH Chapter 4 Vocabulary

Electromagnetic Radiation

The radiation associated with an electric and magnetic field; it varies periodically and travels at the speed of light

Electromagnetic Spectrum

All of the frequencies or wavelengths of electromagnetic radiation

Wavelength

The distance from any point on a wave to an identical point on the next wave

Frequency

The number of cycles or vibrations per unit of time ; also the number of waves produced in a given amount of time

Photoelectric Effect

The emission of electrons from a material when light of certain frequencies shines on the surface of the material

Quantum

The basic unit of electromagnetic energy; characterizes the wave properties of electrons

Photon

A unit or quantum of light; a particle of electromagnetic radiation that has zero rest mass and carries a quantum of energy

Ground State

The lowest energy state of a quantized system

Excited State

A state in which an atom has more energy than it does at its ground state

Emission-Line Spectrum

A series of specific wavelengths of electromagnetic radiation emitted by electrons as they move from higher to lower energy states

Continuous Spectrum

An unbroken sequence of frequencies or wavelengths of electromagnetic radiation, often emitted by an incandescent source

Heisenberg Uncertainty Principle

The principle that states that determining both the position and velocity of an electron or any other particle simultaneously is impossible

Quantum Theory

The study of the structure and behavior of an atom and of subatomic particles from the view that all energy comes in tiny, indivisible bundles

Orbital

A region in an atom where there is a high probability of finding electrons

Quantum Number

A number that specifies certain properties of electrons

Principal Quantum Number

The quantum number that indicates the energy and orbital of an electron in an atom

Angular Momentum Quantum Number

The quantum number that indicates the shape of an orbital

Magnetic Quantum Number

the quantum number that indicates the orientation of an orbital around the nucleus ; symbolized by m

Spin Quantum Number

The quantum number that describes the intrinsic angular momentum of a particle

Electron Configuration

The arrangement of electrons in an atom

Aufbau Principle

The principle that states that the structure of each successive element is obtained by adding one proton to the nucleus of the atom and one electron to the lowest-energy orbital that is available

Pauli Exclusion Principle

The principle that states that two particles of a certain class cannot be in exactly the same energy state

Hund´s Rule

the rule that states that for an atoms in the ground state, the number of unpaired electrons is the maximum possible and these unpaired electrons have the same spin

Noble Gas

One of the elements of Group 18 of the periodic table (helium, neon, argon, krypton, xenon, and radon); noble gases are unreactive

Noble-Gas Configuration

An outer main energy level fully occupied, in most cases, by eight electrons