 Determines the element  Number of protons CANNOT change for an element  Common charge notation is +1  Mass (g) = x  Mass (amu)= = 1

 Common charge notation is 0. No charge!  Mass (g) x (same mass as proton)  Mass (amu)= = 1  Number of neutrons CAN change for an element  ISOTOPES  Stabilizes nucleus by nuclear force

 Common Charge notation is -1  Mass (g) of e- = x  Mass (amu)=.0006 = 0  Number of electrons CAN change for an element  ISOTOPES  Responsible for chemical reactivity, forms bonds

ProtonNeutronElectron LocationNucleus Outside of nucleus Common charge+0_ Mass, g1.673x x x Atomic mass unit, amu

 Which subatomic particle can NOT change for an element and gives its identity?

 Atomic Number: The number of protons in each atom of that element.  The atomic number is located above the element symbol.  Unique to EACH element, never changes!!

 Isotopes: Are atoms of the same element that have different masses.  An Isotope of an element has different number of neutrons. Example of isotopes:

Mass Number: The total number of protons and neutrons that make up the nucleus of an isotope. Common isotopes of carbon Carbon-12 Carbon-13 Carbon-14 *12, 13, and 14 are mass numbers*

 Element- Mass number

 Ions :are when the electron number and proton number are different leading to a net charge.  NOTE: YOU WILL ALWAYS ASSUME ATOMS ARE NEUTRAL (protons = electrons) UNLESS TOLD OTHERWISE

 Atomic #= Proton #= Electron # (because we assume atoms are neutral)  Mass #= Atomic # + Neutron #

 Number of protons= Atomic number  Number of electrons = Number of protons (in a neutral atom)  Number of neutrons = Mass number– Atomic number SymbolAtomic # Mass ## of protons # of electrons # of neutrons Na

 Average atomic mass is the weighted average of the atomic masses of the naturally occurring isotopes of an element  This number appears below the element symbol on the periodic table.