Matter and Energy vocab

energy level
the possible energies that electrons in an atom can have
valence electron
an electron that is in the highest occupied energy level of an atom
an atom or group of atoms that has a positive or negative charge
a neutral group of atoms that are joined together by one or more covalent bonds
a substance that is made from 2 or more simple machines that operate together
ionic bond
the force that hold cations and anions together
a chemical bond in which 2 atoms share a pair of valence electrons
octet rule
atoms have a fuller shell are stable. These atoms don't tend to gain or lose electrons to become stable.
periodic law
the pattern of repeating properties displayed by elements in the periodic table
elements with properties that fall between those of metals and non-metals
noble gas
the element group 8A of the periodic table
the dense, positively charged mass located in the center of an atom
a positively charged subatomic particle that is found in the nucleus of an atom. mass = 1 amu
Atomic Mass Unit
one twelfth the mass of a carbon-12 atom
a neutral subatomic particle that is found in the nucleus of an atom. mass = 1amu
atomic number
a unique number for each element that equals the number of protons in an atom of that element
atoms of a given element that have different numbers of neutrons and different mass numbers
mass number
the sum of the number of protons and neutrons in the nucleus of an atom
a negatively charged subatomic particle that is found in the space outside the nucleus of an atom. mass = 0 amu
electron cloud
a visual model of the most likely locations for the electrons in an atom