a collection of atoms of one type that cannot be broken down into simpler substances by ordinary chemical or physical means

the positively charged subatomic particle contained in the nucleus of an atom

a subatomic particle, contained in the nucleus of an atom, having the same mass as a proton but no electrical charge

a negatively charged subatomic particle that orbits the nucleus of an atom

an arrangement of the elements according to their atomic numbers so that elements with similar properties are in the same column and properties repeat from row to row

one or two letters that represent the name of an element

a unique number for each element that equals the number of protons in an atom of that element

the mass of an atom, calculated by adding the number of protons and neutrons in the nucleus of the atom

a grouping of elements based on similar properties, arranged by columns in the periodic table; also known as a group

a row on the Periodic Table of Elements

one of several forms of a single element, which contains the same number of protons, but different numbers of neutrons

an atom or group of atoms that has gained or lost one or more electrons and is now either positively or negatively charged

The vertical (up and down) columns in the Periodic Table are called

The horizontal (side to side) rows in the Periodic Table are called