6 The Electron Electron Profile Charge: negative Mass: almost zero Location: electron cloud (outside the nucleus)
7 The Atomic NumberThe atomic number is the number of protons in the nucleus of an atomThe number of protons determines the elementAtomic Number
8 Mass NumberThe mass number is the sum of the protons and neutrons in an atom (measured in amu)Mass Number
9 IsotopesIsotopes are atoms that have the same number of protons, but have different numbers of neutrons.
10 Calculating the number of Neutrons in an Atom. How many neutrons are in a Carbon atom with an atomic weight of 14.Atomic weight is the number of protons and neutrons.The atomic number is the number of protons………….so,14 – 6 = 8 neutrons
11 Average Atomic MassThe average atomic mass is the weighted average of the masses of all the naturally occurring isotopes of an element.
12 Calculating the Average Atomic Mass What is the average atomic mass of Chlorine;if 75% is chlorine-35, and25% is chlorine-37?(35 X .75) + (37 X .25) =(26.25) (9.25) = amu