Transcript Slide 1

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?
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?
Practice
• If you had 88g of carbon dioxide, how many CO2
molecules would there be?
• How many moles of CO2 is there in 88g?
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
Periodic Table
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
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
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
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 8889
• Please complete Chemical Building Blocks
workbook page 36-38