Periodic Trends

Goal of the class To understand the trends that exist within the periodic table. Question of the day: How many atoms are in 55g of Iron? Previous question: How many atoms are in 55g of Iron?

Mole The atomic mass can be used to find an amount of atoms The unit used for the amount of atoms is a mole Uses Avogadro's number, NA = 6.02x1023 Example: 12 grams is 1 mole of carbon Different elements, different mass for moles

Example What would be the mass of one mole of water? How many atoms are in one mole of water? Molar mass = 18g / mol There would be 3NA number of atoms 18x1023 atoms

Practice If you had 88g of carbon dioxide, how many CO2 molecules would there be? How many moles of CO2 is there in 88g? Molar mass = 18g / mol There would be 3NA number of atoms 18x1023 atoms

Periodic Table The location in the periodic table can be used to predict the physical and chemical properties Organized based on increasing atomic number After one period chemical properties start to repeat Elements on the left are the most metallic

Periods One row of the periodic table represents one period As you move through the period, the number of valence electrons increases Periods depend on electron orbital shells Bottom row are part of periods 6 and 7 lanthanides and actinides

Periodic Table lanthanides and actinides

Groups Also called families Atoms within the same groups will have similar chemical properties Have the same number of valence electrons Valence electrons give it chemical properties lanthanides and actinides

Electronegativity Electronegativity is the measure of how strong an atom will pull an electron towards it Fluorine has the highest electronegativity Increases as atoms get smaller or fuller electron shells Helps determine chemical reactivity lanthanides and actinides

Ionization energy Ionization energy is the amount of energy needed remove an electron from an atom. Lower energy means the electrons are more easily removed Helps determine the chemically reactivity of the atom or compound lanthanides and actinides

Vocabulary Mole – SI unit of an amount of a substance based on Avogadro's number Avogadro’s Number – NA = 6.02x1023 used for calculating number of atoms in 1 mole. Refractory – A substance that is resistant to heat

Vocabulary Metallic – Made of, appearing to be made of, resembling, or related to metal Electronegativity – the tendency or measure of an atom to attract and form bonds Ionization energy– The energy needed to remove an electron from an atom or molecule to infinity

Homework Read: Chemical Building Blocks page 88-89 Please complete Chemical Building Blocks workbook page 36-38 http://phet.colorado.edu/en/simulation/build-an-atom