chemistry ch 3 vocab

States that matter is composed of extremely small particles called atoms; atoms are invisible and indestructible; atoms of a given element are identical in size, mass, and chemical properties; atoms of a specific element are different from those of another element; different atoms combine in simple whole-number ratios to form compounds; in a chemical reaction, atoms are separated, combined, or rearranged

Dalton's atomic theory

A particle with two protons and two neutrons, with a 2+ charge; is equivalent to a helium-4 nucleus, can be represented by a; and Is emitted during radioactive decay.

alpha particle

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

alpha radiation

The smallest particle of an element that retains all of the properties of that element; is electrically neutral, spherically shaped, and composed of electrons, protons, and neutrons.

atom

The weighted average mass of the isotopes of that element.

atomic mass

One-twelfth the mass of a carbon-12 atom.

atomic mass unit (amu)

The number of protons in an atom.

atomic number

A high-speed electron with a 1- charge that is emitted during radioactive decay.

beta particle

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.

beta radiation

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

cathode ray

A negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus.

electron

High-energy radiation that has no electrical charge and no mass, is not deflected by electric or magnetic fields, usually accompanies alpha and beta radiation and accounts for most of the energy lost during radioactive decay.

gamma ray

Atoms of the same element with different numbers of neutrons.

isotopes

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

mass number

A neutral, subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton.

neutron

A type of equation that shows the atomic number and mass number of the particles involved.

nuclear equation

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

nuclear reaction

The extremely small, positively charged, dense center of an atom that contains positively charged protons and neutral neutrons.

nucleus

A subatomic particle in an atom's nucleus that has a positive charge of 1+.

proton

The rays and particles- alpha and beta particles and gamma rays- that are emitted by radioactive materials.

radiation

A spontaneous process in which unstable nuclei lose energy by emitting radiation.

radioactive decay

The process in which some substances spontaneously emit radiation.

radioactivity