atoms and elements group one

law of conservation of mass

When a chemical reaction takes place, matter is neither created nor destroyed

law of multiple proportions

when two elements combine to form more than one compound, the ratio of the masses of one element that combines with a fixed mass of the other element. is small whole number

law of constant composition

states that a given compound always contains the same elements in the same fixed ratio by mass, no matter where or how it is made.

subatomic particles

A collective term for protons, neutrons, and electrons

electron

A negatively charged subatomic particle found in the space about the nucleus

nucleus

The core of an atom; made up of protons and neutrons

proton

A positively charged subatomic particle found in the nucleus

neutron

An electrically neutral subatomic particle found in the nucleus

atomic mass unit (u)

The unit of a scale of relative atomic masses of the elements; (1u=1/12) of the mass of a carbon atom with six protons and six neutrons

ion

An atom or group of atoms that has lost or gained one or more electrons so that it is no longer electrically neutral; anion, cation

anion

An ion with a negative electric charge

cation

An ion with a positive electrical charge

atomic number Z

The number of protons found in the nucleus of an atom of an element

mass number A

The sum of the number of protons and neutrons in the nucleus of an atom of an element

atomic symbol

The one- or two-letter symbol that represents the element along with the atomic number, written as a subscript number, and the mass, written as a superscript number

monoatomic ion

A single atom that has gained or lost one or more electrons

Isotopes

Atoms with the same atomic number but different mass numbers because of a difference in the number of neutrons

atomic weight

The average mass of an atom in a natural sample of the element

Gravity

An attractive force between objects that have mass.

percent abundance

The percentage of the atoms of a natural sample of the pure element represented by a particular isotop

Electromagnetism

An attractive or repulsive force between charged particles.

periodic table

A table of elements organized by increasing atomic number