1. Subatomic Heavyweights Isotopes of atoms

2. boron atom12345678910 # protons 5555555555 # neutrons 5666656666 # electrons 5555555555 mass number 1011 1011 Which balls are protons, electrons and neutrons? What if had 100, 1000, 1,000,000 B atoms?

3. ElementChemical Symbol Atomic Number Atomic Weight # of protons # of electrons # of neutrons BoronB510.81555 or 6 ChlorineCl1735.4517 18 or 19 LithiumLi36.94333 or 4 VanadiumV2350.9423 27 or 28 NitrogenN714.01777 or 8 MagnesiumMg1224.3012 12 or 13 ArgonAr1839.918 18, 20, or 22 For # of neutrons Round atomic weight up and down. Subtract # of protons from rounded numbers

4. Making Sense How are all the atoms of an element the same? – What doesn’t change? How many protons and neutrons in lanthanum-140? Explain why the atomic masses listed in the periodic table are not usually whole numbers. Is the atomic mass of carbon always the same everywhere in the universe? Do the physical and chemical properties of carbon isotopes differ?

5. Vocabulary Mass number Isotope Atomic mass Skills Know two ways to represent isotopes Determine dominant isotope from atomic mass Calculate atomic mass from isotope distribution Determine # of neutrons from mass and atomic #’s Concepts What is a weighted average? How do isotopes account for the atomic mass? How do isotope phys. and chem. properties differ? stuff to know about isotopes