1. CHEMICAL BONDING THEY CALL IT BONDING…CHEMICAL BONDING

2. Bonding Atoms Why do atoms bond? Why do atoms bond? - each atom wants a full outermost energy level - gain, lose, and share valence electrons to achieve the duet or octet rule aka: “being happy” - gives each atom an electron configuration similar to that of a noble gas ex. Group 18: He, Ne, Ar

3. Chemical Structure/Models Chemical Structure/Molecular Models Chemical Structure/Molecular Models - arrangement of bonded atoms or ions - bond length: the average distance between the nuclei of two bonded atoms - bond angles: the angle formed by two bonds to the same atom

4. Molecular Models of Compounds Ball and stick Ball and stick - atoms are represented by balls - bonds are represented by sticks * good for “seeing” angles Structural Structural - chemical symbols represents atoms - lines are used to represent bonds * good for “seeing” anglesH H O O

5. Molecular Models Cont. Space filling Space filling - colored circles represent atoms, and the space they take up - no bonds, no bond angles Electron Dot/Lewis Structure Electron Dot/Lewis Structure - chemical symbol represent atom - dots represent valence electrons - 2 center dots represent a bond - no bond angles, no bond length

6. Chemical Bonds Chemical Bonds Chemical Bonds - attractive force that holds atoms or ions together - 3 types ionic, covalent, metallic - determines the structure of compound - structure affects properties - melting/boiling pts, conductivity etc.

7. Predicting Bond Type

8. Ionic Bonds / Ionic Compounds Definition Definition - bond formed by the attraction between oppositely charged ions cation: positive: lost e-’s anion: negative: gained e-’s - oppositely charged ions attract each other and form an ionic bond ex. Na + + Cl - = NaCl - electrons are transferred from one atom to another - negative ions attract more positive ions, and soon a network is formed

9. Properties of Ionic Compounds Structure affects properties Structure affects properties - strong attractions between ions: strong bonds - high melting/boiling pt - shatter when struck (think of it as one unit) - conductivity solid: ions are so close together, fixed positions, (can’t move) NO conductivity NO conductivity liquid: ions are freely moving due to a broken lattice structure Good conductivity Good conductivity

10. Covalent Bonds Definition Definition - chemical bond in which two atoms share a pair of valence electrons - can be a single, double, or triple bond single, 2e-’s (-); double, 4e-’s (=); triple, 6e-’s( ) - always formed between nonmetals - mostly low melting/boiling points 2 types of bonds 2 types of bonds - polar - non polar

11. Covalent Bond Cont. Non Polar Non Polar - bonded atoms that share e - ’s equally - same atoms bonded ex. Cl – Cl: Cl 2 Polar Polar - bonded atoms that do not share e - ’s equally - different atoms bonded H ex. H – N – H: NH 3

12. Metallic Bonds Definition Definition - a bond formed by the attraction between positively charged metal ion (cation) and the shared electrons that surround it (sea of electrons) ex. Cu Properties Properties - Conductivity: Good: electrons can move freely - Malleable: lattice structure is flexible

13. Naming Ions Monoatomic Ions Monoatomic Ions - cation -name of element with ion -name of element with ion ex. (Na) Sodium (Na+) Sodium ion - anion - name of element with the suffix –ide ex. (Br) Bromine (Br-) Bromide Ions with multiple cations Ions with multiple cations - transition metals - most form 2 +, 3 + and 4 + ex. Cu +, Cu 2+

14. Naming Metals with Multiple Ions Transition Metals Transition Metals - form multiple ions - in order to name the ion use a roman numeral to indicate the charge ex. Cu 2+ : Copper (II), Titanium (III): Ti 3+ Practice Problems: Fe 3+ : Iron (III) Mercury (III): Hg 3+ Pb 4+ : Lead (IV)Chromium (II): Cr 2+

15. Polyatomic Ions Definition Definition - an ion made of one or more atoms that are covalently bonded and that act as a unit (atoms that have lost or gained electrons) ex. CO 3 2-, NH 4 + - behave the same as other ions - polyatomic ions can combined like any other ion (as a unit) ex. NH 4 NO 3 1:1 ratio (NH 4 ) 2 SO 4 2:1 ratio (NH 4 ) 2 SO 4 2:1 ratio

16. Polyatomic Ions Naming polyatomic ions Naming polyatomic ions - not logical - rules for some compounds -ite & -ate endings -ite & -ate endings - indicates the presence of oxygen - called oxyanions - if (-) does not specify how many oxygen atoms are present ex. Sulfate:4, Nitrate:3, Acetate:2

17. Polyatomic Ions Cont. - often several oxyanions differ only in the number of oxygen atoms present ex. Sulfur - ion with more oxygen takes the –ate ending ex. SO 4 - ion with less takes the –ite ending - ion with less takes the –ite ending ex. SO 3 Common Oxyanions Common Oxyanions * Make sure you know these: memorize

18. Polyatomic Ions Cont. Common Polyatomic Ions Common Polyatomic Ions

19. Naming Ionic Compounds Naming ionic compounds (binary) Naming ionic compounds (binary) Formula to Name - name of cation followed by the name of the anion ex. NaCl: Sodium Chloride ZnO: Zinc (II) Oxide ZnO: Zinc (II) Oxide CuCl 2 : Copper (II) Chloride CuCl 2 : Copper (II) Chloride - formulas must indicate the relative number of cations and ions if transitional

20. Naming Ionic Compounds Practice Problems Practice Problems MgBr 2 Magnesium Bromide KI Potassium Iodide CuCl 2 Copper (II) Chloride Fe 2 S 3 Iron (III) Sulfide

21. Formulas of Ionic Compounds Writing formulas for ionic compounds Writing formulas for ionic compounds Name to Formula - balance the cation charge and anion charge, leaving NO net charge - use subscripts to denote the number of atoms in the formula ex. NaCl: Na + Cl - : NaCl CaCl: Ca 2+ Cl - : CaCl 2 CaCl: Ca 2+ Cl - : CaCl 2 **1 to 1 ratios do not designate charge** **Criss-Cross charges into subscripts**

22. Practice Problems Write the formula for the following atoms Write the formula for the following atoms a.lithium oxide Li 2 O Li 2 O b.beryllium chloride BeCl 2 BeCl 2 c.titanium (III) nitride TiN d.cobalt (III) hydroxide Co(OH) 3

23. Naming Covalent Compounds Prefix System Prefix System # of atomsprefix 1mono 2di 3tri 4tetra 5penta 6hexa 7hepta 8octa 9nona 10deca

24. Naming Covalent Compounds Cont. Rules for the prefix system Rules for the prefix system 1. less electronegative element is given first. It is given a prefix only if it contributes more than one atom to a molecule of the compound 2. The second element is named by combining (a) a prefix indicating the number of atoms contributed by the atom (b) the root of the name of the second element, and (c) the ending –ide 3. The o or a at the end of a prefix is usually dropped when the word following the prefix begins with another vowel ex. Monoxide or pentoxide

25. Naming Covalent Compounds Cont. Naming covalent compounds from formula 1. SiO 2 Silicon dioxide 2. PBr 3 Phosphorus tribromide 3. CI 4 Carbon tetraiodide 4. N 2 O 3 Dinitrogen trioxide Dinitrogen trioxide

26. Writing Formulas for Covalent Compunds Writing formulas from names Writing formulas from names 1.Carbon Dioxide CO 2 2.Dinitrogen Pentoxide N 2 O 5 3.Triphosphorus monosulfide P 3 S 4.Sulfur Monobromide SBr