Unit 5 – The Periodic Table & Chemical Bonding

Objective 1 Identify the position of groups, periods, and different chemical families on the periodic table.

Periodic Table Dmitri Mendeleev – mid 1800’s Proposed a table for 70 elements based on mass and properties Henry Moseley – 1913 Determined the atomic number of elements and arranged the table in order of atomic number

How is the periodic table of elements arranged? Periods: Rows of the periodic table Groups: Columns of the periodic table Periodic Law: When elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical and physical properties.

Groupings to know on the Periodic Table (Fill in on your notes.) Elements (H, He) Metals Non-metals Metalloids Transition Metals Lanthinides Actinides Alkali Metals Alkaline Earth Metals Halogens Noble (inert) gases

Properties of Metals Metals: Bright metallic luster Solids are easily deformed Good conductors of electricity and heat

Properties of Nonmetals Non-lustrous, various colors Solids may be hard or soft, usually brittle Poor conductors of electricity

Properties of Metalloids Metalloids have properties intermediate between metals and nonmetals.

Objective 2 Identify forces between atoms.

Bonding & Reactions The main goal of chemical bonding and reacting is to fill the outermost energy level. Called the octet rule. (8 electrons in the outermost shell, EXCEPT H, He, Li, Be, which only need 2.)

Two Types of Bonds 1.) Ionic 2.) Covalent Brain Pop: Chemical Bonds

Ionic Bonds Electrons are transferred from one atom to another. A metal ion with a positive charge sticks to a nonmetal ion with a negative charge.

Covalent Bonds Non-metals share electrons to fill outer shells. Nonmetals like to gain electrons. Since they all want to gain, they must share.

Practice: Ionic or Covalent Practice: Ionic or Covalent? (Metal + Nonmetal = Ionic Nonmetal + Nonmetal = Covalent) Compound Metal + Nonmetal or Nonmetal + Nonmetal? Ionic or Covalent? NaCl H2O2 C6H12O6 MgF2 Al2O3 CO2 O2 Li3P

Objective 3 Diagram compounds with Lewis dot structures.

Lewis Dot Structures Review Show valence electrons. Look at the group number. This is how many dots you draw for each atom. Ex: Chlorine Hydrogen Calcium Helium (Think carefully here!)

Lewis Dot Structures: Ionic Bonds Ions: an atom that has extra or missing electrons Metals lose their outer electrons, becoming positive. Na Be Al Nonmetals gain electrons in their outer shell, becoming negative. N O Cl

Where do these gained or lost electrons go? Ex: Sodium chloride Metal = sodium nonmetal = chlorine Ex: Magnesium oxide Metal = magnesium nonmetal = oxygen

Use the valence electrons! To find the charge of an ion, look at the valence electrons and count how many they need to give away or add to reach a full energy level (8 electrons for most. 2 electrons for H, He, Li, Be) Ex: What charge will the following ions have? sodium magnesium phosphorous carbon bromine sulfur

Balanced Compound Formula Forming the compound The compound is balanced by crossing charges, reducing if possible. Metal Charge Nonmetal Balanced Compound Formula Li + C = Mg F K O Al P Brain Pop: Ions

Lewis Dot Structures Practice: Ionic Bonds CaCl2 MgBr2 NaCl Na2O

Lewis Dot Structures: Covalent Bonds Non-metals share electrons to fill outer shells. 1 bond = 2 electrons, 2 bonds = 4 electrons, 3 bonds = 6 electrons Follow these rules: (Ex: NCl3) 1.) Look at the formula. Then add up total valence electrons needed. 2.) Single bond all of the atoms, picking a center atom when possible. (H is never in the middle.) 3.) Fill every atoms energy level. Remember, most need 8 electrons, but H only needs 2. 4.) Count the electrons & erase some if you have too many. Move the electrons into double or triple bonds if needed.

Lewis Dot Structures Practice: Covalent Bonds N2 Cl2O2 CI4 CBr4