Formula Writing oxidation number-number assigned to keep track of electron gain or loss lose electron cation + gain electron anion - cation is written first anion is second positive ion first negative ion second METALS (nonmetals) Binary Compound Polyatomic Compounds Compound made of only two elements Compound made of 3 or more elements Definition (Usually metal with nonmetal) (Usually table E, polyatomic ions) Use Criss-Cross

Binary Compound Polyatomic Compounds Second element name ends in “-ide” Second element can end in -”ate” -”ite” -”ium” ONLY -”ide’s”: “peroxide, hydroxide, cyanide Definition Aluminum Sulfide Aluminum Sulfate 1. Look up symbol for the element on Table S Al S 2. Write the oxidation number, (which are found on the Periodic Table, above each symbols as a superscript): Al +3 S Crisscross the oxidation numbers and omit the charge signs. Write the numbers below the symbols as subscripts. Al 2 S 3 Note: The crisscrossing of the oxidation numbers conserves the charge. The sum of the oxidation numbers of all of the atoms in a compound is always zero. 4. When each element has the same oxidation number, these numbers are dropped and the formula is correct as written in step Look up symbol for the element on Table S; polyatomic ion on Table E Al SO 4 2. Write the oxidation numbers, which are found on the Periodic Table, above each symbols as a superscript: Al +3 SO Place the polyatomic ion in parentheses Crisscross the oxidation numbers and omit the charge signs. Write the numbers below the symbols as subscripts. Al 2 (SO 4 ) 3 The sum of the oxidation numbers of all of the atoms in a compound is always zero. 4. When each element has the same oxidation number, these numbers are dropped and the formula is correct as written in step 1.

Sodium Sulfide Na +1 S 2- Na +1 S 2- Na 2 S Sodium Sulfate -ide on PT -ate on Table E Na +1 SO 4 2- ***MUST use parentheses here- if it’s more than one!*** Na 2 SO 4

Naming Compounds Ionic compounds Naming Binary Compounds 1. The element with the positive ionic charge is written first. 2. The second word is formed by changing the ending of the name of the element to “ide”. Example bromine becomes bromide. Metals usually have positive ionic charges Nonmetals (when combined with metals) have negative charges. NaCl sodium chlorine sodium chloride Polyatomic Ions Look up the name of the polyatomic ion on chart table E When polyatomic ion is second 1. write the name of the first element 2. write the name of the polyatomic ion Na 2 SO 4 Sodium sulfate If polyatomic ion first 1. look up ion name 2. follow ending for binary compounds NH 4 Cl ammonium chlorine ammonium chloride

Naming & Writing Compounds Elements with more than one positive oxidation number (Transition Metals) (This is called the Stock System) When the oxidation number varies we us a Roman numeral in parentheses to indicate the charge. Roman number is used for the positive element only!!! (I, II, III, IV, V, VI, VII, VIII, IX, X) FeO Iron (II) oxide Fe 2 O 3 Iron(III) oxide Alternative method for compounds ALL NON METALS ONLY!!! We can also use prefix to indicate the number of each element mon 1, di 2, tri 3, tetra 4, penta 5, hexa 6, hepta 7, octa 8, non 9, deca 10 ***No criss cross*** If the first element is 1, don’t write mono Carbon monoxide CO dinitrogen trioxide N 2 O 3 **TRANSITION METALS!!!!!

Chemical Bonding Chemical bonds are the forces that hold atoms together in a compound. when atoms bond they release energy and become more stable Ionic CovalentMetallic

Ionic Bonds Metal/nonmetal e - is transferred from the metal to the nonmetal EN difference greater than 1.7 Greater the EN difference, greater the ionic character Transfer e -

Ionic Solid hard crystalline high melting and boiling points do not conduct electricity in the solid state do conduct electricity in the molten (liquid) or aqueous state (aq)-electrolyte (ions) NaCl

Covalent Bond 2 nonmetals NonpolarPolar Coordinate Same nonmetals Share the electrons equally Difference of 0 Moochers one atom donates a pair of electrons to be share, the other contributes none H20H20 NH 4 + Share e - Cl 2 CO 2 Different nonmetals Share the electrons unequally Difference of H3O+H3O+

Molecular SubstanceNetwork Solid are brittle in the solid form All 3 states of matter are poor conducts of heat and electricity Low melting and boiling points Hard crystalline Are poor conductors of heat and electricity High melting boiling points C 6 H 12 O 6 CO 2 HCl C-diamond SiO 2 -quartz/sand SiC

Metallic Bonds metals Electrons move freely from one atom to another. “sea of mobile electrons” good conductors of electricity and heat in any state malleable ductile high melting and high boiling points Metals Mobile e

Venn diagram IonicCovalent

Venn diagram IonicCovalent Are forces acting between atoms to hold them together Can form when atoms make contact Either absorb or release energy when formed Create new species with chemical and physical properties unlike constituent atoms Form because atoms want to have complete outer shells Forms when one atom donates electrons to another Exist between ions Holds ions together in an ordered 3-d array, called an ionic crystal Typically exist between atoms on opposite sides of the periodic table Results from electrostatic attraction between opposite charges Forms when atoms share 2,4,6 electrons Builds molecules Can be polar or non-polar Exist between neutral atoms Forms when atoms that tend to gain electrons come into contact with one another Generally form between atoms in the upper right hand corner of the periodic table

Lewis Dot Structure Octet Rule molecules and ions need to have eight electrons in their valance level as the result of bond formation Hydrogen and helium want 2 Rules for drawing an atom. Shows the number of valence electrons for an individual atom or ion Find the number of valence e Put 2 on top Put 1 on each side double up

Ionic Metal/nonmetal Write the formula-tell how many of each atom you need Metal: no dotspositive charge[ ] Nonmetal:8 dotsnegative charge[ ] Aluminum bromide

Covalent 2 non metals 1. Determine the total number of valence e. 2. Draw the skeletal structure. (If only one atom, it will be in the center-central atom.) 3.Put 2 e between each atom. 4.Complete the octet rule for all non-central atoms. 5.Put remaining e on the central atom. 6.Check work. 7. If not enough electrons, make double or triple bonds.

Shapes and Polarity of Molecules Determining Polarity Symmetrical - non polar - opposite sides match Asymmetrical - polar - opposite sides don’t match Cross test + ** MUST be symmetrical in both directions to be considered Non- Polar. “SNAP”

HBr H Br CO 2 O C O CH 4 (non polar) NH 3 H2OH2O Shape Definition Example Ball and Stick Model linear tetrahedral pyramidal bent 2 atoms connected 3 atoms in a line 1 central atom with 4 atoms around it No unpaired e around central atom 1 central atom with 3 atoms around the central Atom 1 pair of e not shared 1 central atom, with 2 other atoms off the central atom 2 pairs of e not shared Always polar Check symmetry C H H H H CH 3 F (polar) N H H H O H H

Intermolecular Forces Are the forces that exist between individual molecules--weaker than a bond Hydrogen Bonding Dipole - Dipole dipole - polar molecule H-Br Atom with the higher EN will be negative. between polar molecules Van der Waals London Dispersion between non polar molecules Diatomic elements Noble gases Organic-C Stronger the intermolecular force, higher the melting and boiling point Ionic > H-bond > Molecular (Covalent molecules) between molecules containing Hydrogen bonded with F, O, N small highly electronegative H-Br *****H-Br H-F **H-F Force is stronger: 1. Closer they are 2. Heavier they are CH 4 ****CH 4

NaCl (aq) Molecule- Ion Attraction Ionic solids when placed in water dissociate ( separate) due to the attraction of opposite charges Polar and ionic (aq) Na + Cl -