Unit Learning Goal  Attraction and repulsion between electric charges at the atomic scale explain the structure, properties, and transformations of matter, as well as the classification of the matter. Attraction and repulsion between electric charges at the atomic scale explain the structure, properties, and transformations of matter, as well as the

Valence Electrons and the Octet Rule

Bonding IonicCovalentMetallic

 Valence Electrons  What are they? ▪ Outer Shell Electrons  These electrons make all bonds happen.

 All atoms “want” to obtain the electron configuration of a noble gas  Usually this is 8 outer shell electrons

 Dots to indicate the number of electrons in the outer shell

 Achieve Noble Gas  Give & Take of Electrons ▪ =Ionic Bond  Sharing Electrons ▪ =Covalent Bond

Ionic Bonding

 Ionic bonds occur because of a Transfer of Electrons

 The oxidation number of an element indicates the number of electrons lost, gained, or shared as a result of chemical bonding. It is the charge of atoms after they have their complete octet.

 Ions are always attracted to each other due to the attraction between opposite electrical charges.  Positive and negative charged ions attract each other till the total charge is ZERO.  1 Na Cl - = NaCl no charge (balanced)

 Definitions  Salt Ionic compounds are often referred to as salts.  Crystal Lattice ▪ A repetitive arrangement of atoms in an ionic compound

One Na for every one Cl

 Formula is a ratio: NaCl does not mean one Na connected to one Cl  It means Na 1,000,000 Cl 1,000,000  So it looks like…

PropertyReason High melting pointDue to strong bonds Do not conduct electricity when solid Electrons can’t move Solids at room temp.Strong bonds Good conductors when dissolved or liquid Ions are free to move Brittle and hardStrong bonds

 Polyatomic Ions are ions that have more than one atom. Often these ions can include nonmetal atoms.  Polyatomic ions are groups of atoms that act together as one unit

 Transition Metals are always cations just like all metals.  Transition Metals often have more than one possible charge. It is necessary to check for possible charges when we make our ionic compounds.

 We must consider these ions as groups that always travel together.

Iron II Oxide`Iron III Oxide

T HE NAME OF COMPOUNDS ARE VERY IMPORTANT ! Because they tell you what is in that compound!

 The periodic table group numbers signify the number of valence electrons members of that group each have.  The valence electron number will indicate whether or not that element/group will lose or gain electrons, and how many  Groups 1-3 and the transition elements lose electrons to become positive ions  Groups 5-7 gain electrons to become negative ions  Group 4 and 8 do not readily form ions

 Ionic compounds are formed between a metal and a nonmetal  Metals: groups 1, 2, 3, & the transition metals (short rows)  Nonmetals: primarily groups 5, 6, & 7  To name them: Cation + (Anion + ide)  Cation: positive ion  Anion: negative ion  Na + Cl = Sodium Chloride

 Compounds are by definition neutral. When combining ions to form an ionic compound, the overall charge of the compound must equal zero  Subscripts are used to indicate the number of each element needed in order to have a neutral compound  For example:  Na + Cl = NaCl (+1, -1 equals zero)  Mg + Br = MgBr 2 (+2, -1, -1 equals zero)

 When naming compounds with polyatomic ions, use the name of the polyatomic ion with no –ide suffix  For example: K 2 S = Potassium sulfide while K 3 PO 4 = Potassium phosphate  In the example above, the rules for determining subscripts remains the same: the goal is for the compound to be neutral (no electrical charge)  K = +1 charge, PO 4 = -3 charge and so I will need three K+ ions to bond with one PO 4 polyatomic ion in order to reach an electrical charge of zero (neutral

 When naming a compound containing an element that can form more than one type of ion, a Roman numeral is used to indicate the charge of that ion in that particular compound  Copper (II) Oxide: Copper has a +2 charge, and therefore the formula will be CuO  Copper (I) Oxide: Copper has a +1 charge and therefore the formula will be Cu 2 O

 When nonmetals combine, the naming system is different.  Because you cannot necessarily use the charge to indicate the quantities of each atom in the compound, the name must indicate the amounts using standard prefixes: mono, di, tri, tetra, penta, hexa, hepta, octa, nona, and deca  The only time a prefix is not used is for the first element of the name when there is only one of that element in the compound.  CO carbon monoxide  N 2 O 4 dinitrogen tetraoxide