CHEMICAL BONDS Atoms must have a complete outer energy level to be stable Most atoms of elements: 1.are not stable 2.will need to gain, lose, or share valence electrons to become stable 3.form chemical bonds to become stable 4.Most elements want 8 valence electrons Exception H and He only want 2 valence electrons

CHEMICAL BONDS Chemical bonds: force that holds together the atoms in a substance Noble gases are stable due to a full outer energy level (family 18) Do not form chemical bonds

LEWIS DOT STRUCTURES (ELECTRON DOT DIAGRAMS) Lewis dot structures (dot diagrams) are used to study chemical bonds Consists of: Symbol dots (for valence electrons)

BONDING Two types of chemical bonds Ionic Bonds Covalent Bonds

IONIC BONDS Ionic bonds: Force of attraction between opposite charges of the ions Involves a transfer of electrons Atoms that have a charge are called ions Particles called crystals are formed Involves a metal and a non-metal Ex. Na ClMgO

COVALENT COMPOUNDS Covalent bond: attraction that forms between atoms when they share electrons Atoms can share 1 or more electrons with another atom Neutral particles called molecules are formed Involves two non-metals or metalloid and non-metal

COVALENT COMPOUNDS Single bond H Cl Double bond O Triple bond N

POLAR AND NONPOLAR Polar molecules are positive and negative ends because one atom has a stronger attraction for electrons Ex. Water Nonpolar molecules is one that does not have oppositely charged ends

Oxidation Numbers Indicates the charge of the atom when it gains, loses, or shares electrons when bonding Know how to use the chart to find oxidation #’s

Formulas subscripts tell how many atoms of that element or group of elements there are no subscript means 1 atom is present coefficients show that there are more than one molecule present parenthesis-subscript goes with all atoms Ex. NaOHHC 2 H 3 O 2 Mg(OH) 2

CRISS-CROSS METHOD TO FORMULA WRITING

POLAR AND NONPOLAR Polar molecules are positive and negative ends because one atom has a stronger attraction for electrons Ex. Water Nonpolar molecules is one that does not have oppositely charged ends

Naming Compounds Ionic Compounds Write the name of the first element Write the name of the second element Change the ending of the second element to –ide If there is a polyatomic ion, leave the name of the polyatomic ion as it is. (do not ever change the name of a polyatomic ion) Covalent Compounds Write the name of the first element If more than one of the first element (a subscript): Give it a prefix If only one of the first element: no prefix Write the name of the second element Give it a prefix (ALWAYS) Change the ending to -ide 1.Determine the type of bond 2.Follow the naming rules for that type of bond Prefixes: 1 mono- 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta- 8 octa- 9 nona- 10 deca-