Chemistry Chapter 4-5 Vocabulary

Isotope

Atoms of the same element with different number of neutrons

Plank's Constant

A fundamental constant of quantum theory that determines the scale of the small scale world. Planck's constant multiplied by the frequency of radiation gives the energy of a photon of that radiation

Neutron

A neutral, subatomic particle in an atom's nucleus that has the same mass nearly equal to the proton

Radioactive Decay

A process in which unstable nuclei lose energy by emitting radiation

Nuclear Reaction

A reaction that involves a change in the nucleus of an atom

Electromagnetic Spectrum

All of the frequencies or wavelengths of electromagnetic radiation

Aufbau Principle

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

Nuclear Equation

Both the atomic number and the mass number must be conserved

Wavelength

Distance between one point on a wave and the nearest point just like it

Gamma Ray

Electromagnetic waves with the shortest wavelengths and highest frequencies

Valence Electron

Electrons on the outermost energy level of an atom

Principal Quantum Number

First quantum number, designated n.

Amplitude

For a wave or vibration, the maximum displacement on either side of the equilibrium (midpoint) position.

Frequency

How many wave peaks pass a certain point per given time

Electron

Negative charge, fast moving particle with an extremely small mass that is found in al forms of matter and moves through the empty space surrounding an atom's nucleus

Atomic Number

Number of protons in an atom

Atomic Mass Unit

One-twelfth the mass of the carbon-12 atom

Alpha Radiation

Radiation that is made up of alpha particles; is deflected toward a negatively charged plate when radiation from a radioactive source is directed between two electrically charged plates

Beta Radiation

Radiation that is made up of beta particles; is deflected toward a positively charged plate when radiation from a radioactive source is directed between two electrically charged plates

Cathode Ray

Radiation that originates from the cathode and travels to the anode of a cathode-Ray tube

Dalton's atomic theory

States that matter is composed of extremely small particles called atoms

Proton

Subatomic particle in an atom's nucleus that has a positive charge

Atomic Emission Spectrum

The discontinuous line spectra of light produced when excited atoms return to their ground state and emit photons of a certain frequency.

Photoelectric Effect

The emission of electrons from a metal when light shines on the metal

Nucleus

The extremely small dense center of an atom that contain positively charged protons and neutral neutrons

Ground State

The lowest energy state of an atom

Mass Number

The number after the element's name, representing the sum of the number of protons and neutrons

Radioactivity

The process in which some substances emits radiation

Radiation

The rays and particles- alpha and beta particles and gamma rays- that are emitted by a radioactive material

Atom

The smallest particle of an element that retains all the properties of that element

Atomic Mass

The weighted average massif the isotope of that element

Electromagnetic Radiation

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

Beta Particle

a high-speed electron or positron emitted in the decay of a radioactive isotope

Quantum Number

a number that specifies the properties of electrons

Alpha Particle

a positively charged atom that is released in the disintegration of radioactive elements and that consists of two protons and two neutrons

Atomic Orbital

a region of space in which there is a high probability of finding an electron

Electron-dot Structure

a shorthand notation of the shell model of the atom

Photon

a tiny particle or packet of light energy

Hund's Rule

electrons do not pair up until they have to

Heisenberg Uncertainty Principle

it is impossible to know exactly both the velocity and the position of a particle at the same time

de Broglie Equation

predicts that all moving particles have wave characteristics

Quantum

the amount of energy needed to move an electron from one energy level to another

Electron Configuration

the arrangement of electrons in an atom

Energy Sublevel

the energy levels contained within a principle energy level

Principal Energy Level

the major energy levels of an atom

Quantum Mechanical Model of the Atom

the modern description, primarily mathematical, of the behavior of electrons in atoms