Holt McDougal Chemistry 4.1

Waves and Particles

Light’s properties can be described in these terms.

Electromagnetic Radiation

A form of energy that exhibits wavelike behavior as it travels through space. Examples include visible light, X-rays, ultraviolet and infrared light, microwaves, and radio waves.

Electromagnetic Spectrum

All the forms of electromagnetic radiation, often expressed on a form of number line.

3.00*10^8 m/s

The speed of electromagnetic radiation through a vacuum.

Wavelength

The distance between corresponding points on adjacent waves. Unit is any distance unit depending on the type of electromagnetic radiation.

Frequency

The number of waves that pass a given point in a specific time, usually one second. Expressed in waves/second, which is also called a hertz (Hz)

C=(Frequency)(Wavelength)

The mathematical relation between frequency and wavelength where C is a constant.

Photoelectric Effect

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

Frequency

No electrons are emitted from a given metal if the light’s _______________ is below a certain minimum, regardless of intensity. Different metals need different values of this.

Quantum (of Energy)

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

Quanta

Small, specific packets of energy that are emitted from hot objects (or any object giving off energy).

Photon

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

Whole Numbers

Electromagnetic radiation is absorbed by matter only in ___________ ___________ of photons.

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 of these with a unique energy.

Given Off

Energy is _______ _______ in the form of electromagnetic radiation when an atom returns to a ground state or moves to a lower excited 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; those bands of light make up [an element]’s [this].

Continuous Spectrum

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

Quantum Theory

Entirely new atomic theory that attempts to explain why hydrogen atoms only give off specific frequencies of light.

Fixed

When an electron is in an orbit/energy level, the atom’s energy is _______.

Lowest

An [hydrogen] atom is in its ___________ energy state when its electron is in the energy level nearest the nucleus.

Increases

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

Gaining

An electron can move to a higher-energy orbit by __________ energy equal to the difference in energy between the orbits.

Emission

Process by which an electron falls to a lower energy level and releases a photon; the photon’s energy is equal to the energy difference between the levels.

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.