Chemistry Vocabulary Part 1 by Meghan Goodell

Matter Anything that has mass and takes up space

Element  Matter made of atoms of only one kind  Example: Iron is an element made of iron atoms

Electron  Negatively charged particle that exists in an electron cloud around an atom’s nucleus

Proton  Positively-charged particle in the nucleus of an atom

Neutron  Electrically-neutral particle that has the same mass as a proton and is found in an atom’s nucleus

Atomic Number  Number of protons in the nucleus of an atom of a given element Hydrogen has one proton and one neutron, what is its atomic number? 1

Mass Number  The sum of neutrons and protons in the nucleus of an atom Hydrogen has one proton and one neutron, what is its mass number? 2

Period  Horizontal row of elements in the periodic table whose properties change gradually and predictably

Group  Family of elements in the periodic table that have similar physical or chemical properties

Representative Element  Elements in groups 1 and 2 along with in the periodic table that include metals, metalloids, and non metals.

Transition Element  Elements in groups 3-12 in the periodic table, all of which are metals.

Metalloid  Element that shares some properties with both metals and nonmetals.