Covalent (Molecular) compounds and Chapter 7 & 8 Bonding
Where are covalent compounds found? Water Sugar Cooking Oil Protein Candle wax Chocolate Lipstick Plastics Paper Cotton Fingernail polish Hair Food Mothballs
Bonding Bonds can form when atoms share electrons, called a covalent bond. Occurs between 2 or more nonmetals. A molecule is formed when we have a covalent bond. Formula unit is used for ionic compounds.
Molecular Compounds These are composed of two or more non-metals and form molecules covalently bonded (they share valence electrons). Because of the weak forces, molecules have low melting and boiling points. Can t use charges to figure out how many of each atom Many are flammable not very soluble in water Variety of colors of compounds Nonconductors of electricity and heat Are not electrolytes
Smallest piece is called a molecule Valence electrons are shared by atoms not transferred so NO ions. Typically are gases and liquids at room temperature If a solid, soft and brittle (amorphous solids) If in a network then hard and brittle (diamond & graphite) Few are crystalline (diamond & sugar)
Characteristics Covalent compounds are held together by weak forces called intermolecular forces or van der Waals forces 1. Nonpolar molecules: dispersion forces (weakest) 2. Polar molecules: dipole-dipole force (middle) 3. Hydrogen bonds: occur between H and another highly electronegative atom (strongest)
How to tell the type of bond Find the electronegativity difference on the back of the PT. Pure covalent [(0.4) polar cov [(1.7) ionic (non-polar) Lowercase delta (δ) means partially So δ- means the atom has a slight negative charge but not enough to be an ion
Bond Polarity a) Metallic: delocalized valence e-, (sea of electrons), piece of metal, good electrical conductors, very strong bond, very high mp/bp. Ex. Gold ring, copper wire, steel basket, etc. b) Ionic: usually metals with non-metals, absolute Electronegativity difference greater than 1.7, brittle, high mp/bp, strong bond, hydrophillic. So e- have been transferred from Ca to Cl, will form 3 separate ions in solution, Ca 2+ Cl 1- Cl 1-
c) Pure covalent bond: generally nonmetals, electrons shared equally between the 2 atoms, weak bonds, low mp/bp, hydrophobic, lipophilic Electronegativity difference < 0.4 Ex. Methane (CH 4 ) 2.55-2.20 = 0.35 d) Polar covalent bond: generally nonmetals, electrons shared unequally between the 2 atoms, weak bonds, low mp/bp, hydrophilic, lipophobic
Examples Ex. Ca Cl 2 1.0-3.16 = 2.16 Hint: look at each bond individually (don t multiply by 2) So bond is ionic Ex. Water H 2 O 3.44-2.20 = 1.27 So bond is polar covalent For polar compounds draw the delta and delta + Ex δ- O H δ+ The element with the highest electronegativity gets the δ-.
Naming Molecular Ionic compounds use charges to determine how many of each. Have to figure out charges. Have to figure out numbers of atoms. Molecular compound name tells you the formula. Uses Greek prefixes to tell you the number of atoms, NOT Roman numerals
Prefixes (See Ion Sheet) 1 = mono- 2 = di- 3 = tri- 4 = tetra- 5 = penta- 7 = hepta- 8 = octa- 9 = nona- 6 = hexa- 10 = deca- Exception is: we only write mono- if there is no other prefix used.
Name These N 2 O NO 2 Cl 2 O 7 CBr 4 CO 2 Water? Ammonia? Methane? BaCl 2
Write formulas for these 1. diphosphorus pentoxide 2. tetraiodine nonoxide 3. sulfur hexafluoride 4. nitrogen trioxide 5. carbon tetrahydride 6. phosphorus heptafluoride 7. xenon octachloride
Name these molecular compounds (for a grade) 1. NO 2 9) H 2 O 2 2. N 2 O 10) N 5 O 10 3. CO 11) CCl 4 4. C 2 H 6 O 7 12) CH 3 O 4 5. H P O 4 6. H Se 6 Cl 7. C 7 H 8 N 9 8. H 8 Br 6
Name these molecular compounds (for a grade) 1. NO 2 2. N 2 O 3. CO 4. C 2 H 6 O 7 5. H P O 4 6. H Se 6 Cl 7. C 7 H 8 N 9 8. H 8 Br 6 9. H 2 O 2 10. N 5 O 10 11. CCl 4 1. nitrogen dioxide 2. dinitrogen oxide 3. carbon monoxide 4. dicarbon hexahydrogen heptoxide 5. hydrogen phosphorous tetroxide 6. hydrogen hexaselenium chloride 7. heptacarbon octahydrogen nonanitride 8. octahydrogen hexabromide 9. dihydrogen dioxide 10.pentanitrogen decoxide 11.carbon tetrachloride 12.carbon trihydrogen tetraoxide 12. CH 3 O 4
Bellringer 1. Name H 2 O 2 2. Write the formula for nitrogen monoxide 3. Ionic compounds are made of a and a in general. 4. Covalent compounds are made of a and a in general. 5. Of the 2 types, have higher melting points.
Quiz warm-up Use the Ion Sheet for electronegativities. 1. List the 3 types of intermolecular forces. 2. What type of IF do polar compounds have? 3. What is a dipole? 4. Determine the type of bond in P-I 5. Draw the bond and indicate any partial charges in C-F 6. Name C 2 H 6 O 7 7. What is a network solid, is it ionic or covalent and give an example.
GEN Quiz warm-up Use the Ion Sheet for electronegativities. 1. The 4 types of bonds are,. and. 2. Bonds that have a total separation of charges are called. 3. Bonds with partial charges are called. 4. A partial charge is indicated with the Greek letter. 5. Determine the type of bond in P-I 6. Draw the bond and indicate any partial charges in C-F 7. Name C 2 H 6 O 7 8. Name SH 3 N 4
Videos Convert diamond to graphite https://www.youtube.com/watch?v=7l7bv3ibffa Tyler Ionic vs Cov https://www.youtube.com/watch?v=pka4czwbzwu Covalent bonding https://www.youtube.com/watch?v=mo4vfqt5v2a Ionic covalent or polar? https://www.youtube.com/watch?v=6twrhdevc-a Hydrogen bonds https://www.youtube.com/watch?v=pyc5r2mb4d4 Properties of compounds https://www.youtube.com/watch?v=bq6_8imd8ym Amorphous vs Crystalline https://www.youtube.com/watch?v=nnrxve8yxg4 Diamonds from peanut butter https://www.youtube.com/watch?v=_cb74y_p1g8
Acids Characteristics, Writing names and Formulas
Acids These compounds produce hydrogen ions (H+) when dissolved in water (also written as H 3 O 1+, hydronium ion ).
Acids There will usually be an H next to an anion. Sour tasting, turn litmus red, corrosive There are 3 main definitions of acids which will be covered in another chapter.
Naming Binary acids If the anion attached to hydrogen ends in -ide, put the prefix hydro- and change ide to -ic acid HCl... hydrogen ion and chloride ion = hydrochloric acid H 2 S..hydrogen ion and sulfide ion = hydrosulfuric acid
Ternary acids (H and 2 elements) per -ic (has most oxygen) if anion is ate, change to ic if anion is ite, change to ous hypo -ous (has least oxygen) Ex. SO 4 2- is sulfate so H 2 SO 4 is Ex. SO 3 2- is sulfite so H 2 SO 3 is Sulfuric acid Sulfurous acid HNO 3 = anion is nitrate, the suffix -ate changes to -ic so is Nitric acid HNO 2 = anion is nitrite, the suffix -ite changes to -ous.so is Nitrous acid
Try these! Name as ACIDS HCl HNO 3 HNO 2 H 3 PO 4 H 2 CO 3 Hydrochloric acid Nitric acid Nitrous acid Phosphoric acid Carbonic acid
Writing Acid Formulas Hydrogen will always be first name will tell you the anion make the charges cancel out. Starts with hydro?- no oxygen, -ide no hydro?, -ate comes from - ic, -ite comes from -ous
Assignment Acid Practice 1 Name these as covalent AND as acids 1. HF 10. HClO 2. H 3 P 11. HClO 2 3. H 2 SO 4 12. HClO 3 4. H 2 SO 3 13. HClO 4 5. HCN 14. H 3 PO 3 6. H 2 CrO 4 15. H 3 PO 4 7. Hydroiodic acid 16. Acetic acid 8. Carbonic acid 17. Phosphorous acid 9. Hydrobromic acid 18. Bromic acid
Name these 1st 1. HF 7. HClO 2. H 3 P 8. HClO 2 3. H 2 SO 4 9. HClO 3 4. H 2 SO 3 10. HClO 4 5. HCN 6. H 2 CrO 4
Write formulas for these hydroiodic acid acetic acid carbonic acid phosphorous acid hydrobromic acid
Helpful to remember... 1. In an ionic compound, the net ionic charge is zero (criss-cross method) 2. An -ide ending generally indicates a binary compound 3. An -ite or -ate ending means there is a polyatomic ion that has oxygen 4. Prefixes generally mean molecular; they show the number of each atom 5. A Roman numeral after the name of a cation shows the ionic charge of the cation
Practice 1 Calcium oxide 6 Na 3 P 2 Cobalt (III) oxide 7 Fe 3 P 2 3 Diphosphorous tetroxide 8 N 2 O 7 4 Sulfuric acid 9 H 2 SO 3 5 Hydrosulfuric acid 10 H 3 P
Hints for Naming Acids Hydrogen is the first element in an acid Rules 1. If made of only 2 types of elements, the name starts with hydro- 1. The 2 nd element is named and the ending is ic 2. Add the word acid to the end 2. If a polyatomic, 1. if the name of the polyatomic ends in ate, replace with ic 2. if it ends with ite, replace with ous 3. Add acid to the end
Examples HI = Hydrosulfuric acid = Sulfurous acid = Sulfuric acid = H 3 PO 4 =
Name as acids: 1) HF 2) H 2 CO 3 3) H 2 S Lab today, Quiz Friday over acids 4) H 3 PO 3 5) HC 2 H 3 O 2
Write the formula 6) Sulfurous acid 7) Oxalic acid 8) Phosphorous acid 9) Hydrotelluric acid 10)Boric acid
Bellringer 1. The ph scale goes from to. 2. Acids are on the ph scale. 3. Write the formula for Hydrotelluric acid. 4. Write the formula for Boric acid. 5. Name H IO 3 as an acid.
Hydrates Compounds (covalent or ionic) with water trapped in the crystal (and formula) Do not look wet A colorful example is cobalt(ii) chloride, which turns from blue to red upon hydration (used as a water indicator). Anhydrous = no water in the crystal Anhydrous cobalt(ii) chloride CoCl 2 Hydrated Cobalt(II) chloride hexahydrate CoCl 2 6H 2 O
Name as an ionic compound, then add a Greek prefix to indicate the number of water molecules. Ex. Name Cu SO 4. 5 H 2 O Copper (II) sulfate pentahydrate Ex. Name: Zn PO 4. 3 H 2 O Zinc phosphate trihydrate
Naming Hydrates 1) Cu (NO 3 ) 2 3 H 2 O 2) Al (OH) 3 6 H 2 O 3) Cu NO 3 9 H 2 O 4) Fe (NO 2 ) 2 H 2 O 5) Zn (CN) 2 6 H 2 O
http://www.chemteam.info/nomenclatur e/hydrate.html Chem team hydrates
Tutorials Formulas compounds: http://www.bing.com/videos/search?q=ionic+bond+vide o&view=detail&mid=3888cfdf908299747f233888cfdf908 299747F23&first=0&qpvt=ionic+bond+video Naming compounds: http://www.bing.com/videos/search?q=ionic+bond+vide o&view=detail&mid=3888cfdf908299747f233888cfdf908 299747F23&first=0&qpvt=ionic+bond+video Junior chem formulas http://www.bing.com/videos/search?q=ionic+compound s&view=detail&mid=3df42fcae87f9787c4413df42fcae8 7F9787C441&first=41