2 Types of Chemical Bonds: A. Ionic Bonding1) Positively charged ions are attracted to negativelycharged ions, making a neutral compound.2) Properties of Ionic Compounds:a) high melting points.b) dissolve in water to form solutions that are good conductors of electricity (electrolytes).c) have a large electronegativity differencebetween elements.d) usually form between metals and nonmetals.
3 3) The Octet Rule:Atoms tend to gain or lose electrons in order to acquire a full set of valence electrons (stable octet).b) Atoms will transfer electrons (e-) to each other in order to have a full set of valence electrons.c) When electrons are transferred, ionic bonds are formed.
4 Ions Atoms can form ions by gaining or losing electrons. Metals tend to lose one or more electrons to form positive ions called cations.Cations are generally named by using the name of the parent atom.
5 IonsNonmetals tend to gain one or more electrons to form negative ions called anions.Anions are named by using the root of the atom name followed by the suffix –ide.
11 4) Types of Compounds:b) Tertiary form from polyatomic ions which consists of a group of atoms covalently bonded with a single charge that bond ionically with other ions.Ex.“ammonium sulfate” ,NH4+1SO4-2(NH4)2SO4
12 X Name this compound: FeO If that’s correct, name this: Fe2O3 How can we distinguish between these compounds?What is the charge on the oxygen in each compound? Then what is the charge on the iron in each compound?Fix the name of the first compound:Iron oxideIron (II) oxideFe+2 O-2Fe+3 O-2Iron (III) oxide
14 5) Polyvalent Metals:Some metals including the transition metals do not follow the octet rule and may form more than 1 kind of cation. These ions are named with roman numerals to distinguish between them.Ex) Fe+2 iron (II) read “iron two”Fe+3 iron (III) read “iron three”FeCl2 iron (II) chlorideFeCl3 iron (III) chlorideCopper (I) sulfateCopper (II) phosphateCu2SO4Cu3(PO4)2
15 6) Lewis Dot Diagrams for elements: # of val. ElectronsDot DiagramLi1LiN5Be2F7Ne8AuC4
17 7) Lewis-dot diagram for sodium chloride: [Na+] [ ]
18 B. Covalent Bonding 1) Covalent Bonds are formed by sharing pairs of electrons between 2 atoms.2) Usually formed between two nonmetals with a low electronegativity difference.3) Molecules:a) a group of atoms held together by covalentbondsb) molecular substance – contains molecules
19 4) Naming: uses prefixes: 1 mono- 4 tetra- 7 hepta- 10 deca- 2 di penta- 8 octa-3 tri hexa- 9 nona-b) end in “ide”c) More electronegative element is written lastd) Only use a prefix on the first element if it is more than one.e) Always use a prefix for the second element.Ex) water H2O dihydrogen monoxidesmog NO nitrogen dioxide
20 5) Types of formulas for covalent bonding a) Molecular Formula shows how many atoms make up a compound.ex. CH4 & H2Ob) Structural Formula shows how the atoms are bonded to each other.ex.
21 1. Uses 2 dots to show an unshared pair of electrons.2. Uses dashes to represent covalent bonds (ashared pair of electrons) in a structural formula.3. The octet rule should be satisfied for each element in the compound.c) Empirical Formula is the lowest whole number ratio of all the elements in the compound.Ex) C6H6 = CHC6H12O6 = CH2O
22 6) Multiple Bonds – can be used to satisfy the octet rule Single Bonds – Share 1 pair of electrons.Ex) methane or phosphorous trichloride
26 8) Properties of Covalent Bonds a) Low melting points, brittle, strong odor, poor conductors of electricity.b) Polar Bonds – form between elements with large differences in electronegativity. These have an uneven sharing of electrons.Ex) waterpartial negative sidepartial positive side
27 c) Nonpolar bonds – exert equal pull on the electrons. Ex) O2
28 9) Electronegativity Chart is used to determine bond type non polar covalent polar covalent ionic bonds0.41.94.0even sharing - no chargeEx) O2uneven sharing – slight charge on moleculeEx) H2Oelectrons transferred – forms ionsEx) NaCl
31 C. Ionic & Covalent Bonds Summary: Ionic BondingCovalent Bondingmetal-nonmetalnonmetal-nonmetale- transferrede- sharedlarge electronegativity difference (>1.9)electronegativity difference (0 1.9)ions formedno ionswritten cation (+) anion (-)more electronegative element written lastname cation - name anionuse # prefixes/ends in ideforms ionic compound (formula unit) in a crystal latticeforms moleculesWritten with a chemical or empirical formulaWritten with a molecular or structural formulaNaCl – sodium chlorideCCl4 – carbon tetrachloride
34 D. Acids:1) A molecular compound that dissolves in water to produce H ions and a characteristic anion.2) In water, acids behave like ionic compounds.3) Most acid formulas begin with H. (Except organic acids) “ COOH”4) The number of hydrogens in the formula depends upon the charge of the anion.
35 5)Types of Acids a.) Organic Acids contain the carboxylic group, -COOH orEx) CH3COOH acetic acid (vinegar)(or HC2H3O2)
36 b.) Binary Acids contain hydrogen and 1 type of anion. A two-word name is used for binary acids.1st word: prefix is “hydro”root is formed from the anionanion suffix “ide” is changed to “ic”2nd word: is “acid”Ex) HCl anion is chloride hydrochloric acidPrefix root suffixHBr anion is bromide hydrobromic acidH3P anion phosphide hydrophosphoric acid
37 c.) Oxo (Tertiary) Acids: contain oxygen within a polyatomic ion. A two-word name is used for oxo acids.H2SO sulfate sulfuric acidH2SO3 sulfite sulfurous acidsulfur or phosphor (to sound better)2nd word is “acid”If you “ate” something you don’t like, you say “ic”“ite-ous”
38 HNO3 anion is nitrate nitric acid root suffixH3PO3 anion is phosphite phosphorous acidNitrous acid, anion is nitrite formula is: HNO2Phosphoric acid, anion is phosphateformula is: H3PO4
39 E. Hydrates: 1.) Ionic compounds that absorb H2O into their solid structures.Ex) magnesium sulfate heptahydrate (epsom salt)Formula: MgSO4 7H2O2.) Anhydrous substance – substance without water MgSO4Ex) CuSO4 • 5H2O copper (II) sulfate pentahydrate (bright blue)CuSO4 – anhydrate (light blue/white)