Bonding p

chemical bond: interaction between atoms or ions –decreases the potential energy of an atom; makes it more stable –only the valence electrons are involved!

Three Types of Bonds Bond type depends on electronegativity (electron affinity) –IONIC ： very different electronegativities one metal, one non-metal –COVALENT: both very high two non-metals –METALLIC: both low one or more metals

Review of Ionisation Metals Non- metals Cations Anions

What kind of bond? Na and Cl O and F K and Br Au and Ag H and O Mg and F S and Cl Ni and Cu Ionic Covalent Ionic Metallic Covalent Ionic Covalent Metallic

Ionic Bonds metal (low electroneg., cation) + non- metal (high electroneg., anion) Array of positively and negatively charged ions –held together by electrostatic attraction

metal loses e - = cation –group 1 (+1) and group 2 (+2) –transition metals (+2 most common) non-metal gains e - = anion –groups 17, 16, 15… List, p. 100

sodium and chlorine sodium transfers its electron to chlorine Na Cl

Crystal Lattice (Array) structure of an ionic bond each anion is surrounded by cations and vice versa

Writing Formulae for Ionic Compounds

chemical formula: shorthand for elements, ions and compounds Ratio of the number of atoms of each element –MgCl 2 –C 6 H 12 O 6

Ions of opposite charges are attracted to one another. Mg 2+ Cl - MgCl 2 Ions bond because they are electrically attracted to one another –“Opposites attract”

Polyatomic ions: most covalently bonded, but have an overall electronic charge Hand out list: memorize it.

Ionic or Covalent? NaCl NO 2 N 2 Br NaI CaS

Ionic or Covalent? KNO 3 Fe(CrO 4 ) 2 Cu(OH) 2 BaI F 2

Ionic or Covalent? O 2 AgCl AgNO 3

Ionic or Covalent? NO 2 CO 2 PCl 5 P 2 S 4 NO 3

Writing Formulae for Ionic Compounds Write the symbols and their charges “Cross” the charges to the other side Use the charges, without + or – as subscripts

Polyatomic Ions to Memorize Ammonium Nitrite Nitrate Sulfite Sulfate Hydroxide Phosphite phosphate Carbonate Chlorite Chlorate Chromate

Naming Ionic Compounds

Naming Cations Same as the element!!

Naming Anions Ending changes to “ide” Ooxygenoxide Ffluorinefluoride S sulfursulfide Clchlorinechloride Brbrominebromide Iiodineiodide

Chlorine Iodine Oxygen Sulfur Bromine Fluorine Chloride Iodide Oxide Sulfide Bromide Fluoride

Naming Ionic Compounds Cation + Anion (“ide” ending) NaClsodium chloride KBrpotassium bromide

Naming Ionic Compounds – Type I One positively charged ion and one negatively charged ion. NaCl –Sodium chloride SrF 2 –Strontium fluoride

1.CsBr 2.MgO 3.KF 4.AlCl 3 5.LiH 6.calcium iodide 7.rubidium sulfide 1.cesium bromide 2.magnesium oxide 3.potassium fluoride 4.aluminum chloride 5.lithium hydride 6.CaI 2 7.Rb 2 S

LiI CaS AgBr ZnCl 2 Na 2 S barium fluoride silver oxide lithium iodide calcium sulfide silver bromide zinc chloride sodium sulfide BaF 2 Ag 2 O

Stock system Some elements make ions with different charges (p. 100) –“oxidation states” Fe 2+ Fe 3+ iron(II) iron(III) Roman numerals

Elements that use the Stock System These elements have more than one “oxidation state” –Fe (2+, 3+) Cr (2+, 3+) –Cu (1+, 2+)Mn (2+, 3+) –Co (2+, 3+)Pb (2+, 4+) –Sn (2+, 4+) –Hg 2+ (mercury II), Hg2 2+ (mercury I) –Zumdahl, p. 65

Ions to memorize Al 3+ Zn 2+ Ag + Cd 2+

1.CuCl 2.SnO 3.Fe 2 O 3 4.MnO 2 5.PbCl 2 6.copper (III) oxide 7.vanadium (IV) fluoride copper (I) chloride tin (II) oxide iron (III) oxide manganese (IV) oxide lead (II) chloride Cu 2 O 3 VF 4

1.CoBr 2 2.CrCl 3 3.CaCl 2 4.Al 2 O 3 5.SnBr 4 6.Cu 2 S 7.iron (II) fluoride 8.tin (II) oxide cobalt (II) bromide chromium (III) chloride calcium chloride aluminum oxide tin (IV) bromide copper (I) sulfide FeF 2 SnO

Fe(NO 3 ) 3 –Iron(III) nitrate Fe 2 (SO 4 ) 3 –iron(III) sulfate Polyatomic Ion

Ionic Compounds with Polyatomic Ions NH 4 + –ammonium NO 3 - –nitrate

1.Na 2 SO 4 2.KH 2 PO 4 3.Fe(NO 3 ) 3 4.Mn(OH) 2 5.Na 2 SO 3 6.Rb 2 CO 3 7.Mg(HCO 3 ) 2 1.sodium sulfate 2.potassium dihydrogen phosphate 3.iron (III) nitrate 4.manganese (II) hydroxide 5.sodium sulfite 6.rubidium carbonate 7.magnesium bicarbonate

Name Ionic Compounds KNO 3 Mg(OH) 2 LiCrO 4 Fe(OH) 3 Co(NO 3 ) 2 Mn 3 (PO 3 ) 2 potassium nitrate magnesium hydroxide lithium chromate iron (III) hydroxide cobalt nitrate Manganese (II) posphite potassium nitrate magnesium hydroxide lithium chromate iron (III) hydroxide cobalt nitrate Manganese (II) posphite

Homework 1.CaO 2.lithium sulfide 3.CrCO 3 4.silver iodide 5.Cu 2 SO 3 6.calcium phosphate 7.SrI 2 8.iron (III) bromide 9.FeBr 2 10.cobalt (II) iodide 11.SnO 2 12.ammonium nitrate 13.Ag 2 S

Covalent Bonding

two or more non-metals atoms share some valence electrons (not transfer) single covalent bond: shares one pair of electrons double: 2 pairs of e - triple: 3 pairs of e -

usually each atom donates (shares) one of each pair of electrons dative covalent bond: sometimes one atom donates both electrons F F Electron Pair Shared by both atoms Each e- donate by each atom

number of bonds formed depends on the number of e - required to fill the valence shell –noble gases = full valence, rarely form compounds octet rule: usually, atoms want 8 valence e - (H, He need 2)

Ex: C has 4 valence e- –needs 4 more to form a full octet –C forms 4 bonds Ex: F has 7 valence e- –needs 1 more to form a full octet –F makes one bond Nitrogen?

Bonding between C and F F F F F C structural hybrid Lewis formula diagram diagram =e- pair F e - C e - =covalent bond F F F F C F F F F C

Double Bond sharing two pairs of electrons bonds more strongly than a single bond structural hybrid Lewis COO COO COO

Triple Bond Strongest NN NN NN

Length and Strength of Bonds single double triple longest shortest lowest energy highest energy

Drawing molecule diagrams 1.Decide how many bonds each atom makes. 2.The central atom is the one that makes the most bonds. 3.Draw with single bonds 4.Calculate remaining electrons 5.Use remaining electrons

HCN (hydrogen cyanide) –C=4, N=3, H=1 HCO 2 - (methanoate ion) –H=1, C=4, O=2

Draw structural, hybrid and Lewis structures HF NH 3 CH 4 CF 4 NO 2 - CHCl 3 NH 4 + H 2 CO SeF 2

Naming Covalent Compounds Ex: CO 2 –carbon dioxide Prefixes –mono1 –di2 –tri3 –tetra4 –penta5 –hexa6

1.N 2 O 2.NO 3.NO 2 4.N 2 O 3 5.N 2 O 4 6.N 2 O 5

1.Phosphorus pentachloride 2.Phosphorus trichloride 3.Sulfur hexafluoride 4.Sulfur trioxide 5.Sulfur dioxide 6.Carbon dioxide 1.Phosphorus pentachloride 2.Phosphorus trichloride 3.Sulfur hexafluoride 4.Sulfur trioxide 5.Sulfur dioxide 6.Carbon dioxide

P 4 O 10 Fe 2 O 3 Li 2 O 2 Mg(NO 3 ) 2 CCl 4 tetraphosphorus decoxide iron (III) oxide lithium peroxide Magnesium nitrate Carbon tetrachloride tetraphosphorus decoxide iron (III) oxide lithium peroxide Magnesium nitrate Carbon tetrachloride

Homework NI 3 phosphorus trichloride SF 2 dinitrogen tetrafluoride N 2 O 4 sulfur dioxide ICl 3 diphosphorus pentasulfide SF 6 dihydrogen monoxide