Chemical Bonding

1. Chemical Bonding

2. Chemical Bonds / Formulas • Atoms bond to become “happy” – octet rule • When they bond they form compounds. • Each compound has a special formula • Subscripts show how many of each element is in the compound

3. FORMULAS MgCl2 • The subscript is the number at the bottom of a formula. • There is 1- Mg & 2 – Cl • Never use 1 as a subscript!

4. IONIC BONDformed between two ions by the transferof electrons

5. Formation of Ions from Metals • Ionic compounds result when metals react with nonmetals • Metalslose electrons to form a positive charge • Nonmetalsgain electrons to form a negative charge • Metals:Nonmetals: Na+ N -3 Ca+2 S -2 Al+2 Br -

7. IONIC BONDS • Bonds form from the (+) & (-) charges. • Form a network of ions. Form strong bonds. • Conduct electricity when melted or dissolved in water.

9. Writing Ionic Formulas – binary Calcium & oxygen Write the metal ion Ca +2 Write the nonmetal ion O -2 If charges cancel – ratio is 1:1 ( 1 of each) CaO Magnesium & chlorine Write the metal ion Mg +2 Write the nonmetal ion Cl- If charges DO NOT cancel – drop & swap MgCl2

10. Transition Metals – d & f block • Ion charges change – an element can have more than one ion charge • The charge is given as a ROMAN NUMERAL • Ex: Iron (II) Fe+2 / Iron (III) Fe+3 • Gold (I) Au + / Gold (III) Au+3 • You will not have to memorize all the charges each transition metal forms – the charges will be given to you !!!!!

11. Practice • Magnesium & iodine • Iron (III) & bromine • Barium & nitrogen • Aluminum & phosphorus

12. Naming Ionic Formula - binary • Representative Metals • Name the metal • Change the ending of the nonmetal to – ide Ex: MgCl2 - magnesium chloride AlP - aluminum phosphide • Transition Metals • Name the metal & Include the charge using a Roman Numeral • Change the ending of the nonmetal ending to –ide Ex: Fe +2 Cl- iron (II) chloride Au + O -2 gold (I) oxide

13. Practice • CaBr2 • Na3N • BCl3 • MgO • FeCl3 • Ni3N • ZnO • FeS

14. Ternary Ionic Bonds – contain Polyatomic Ions • Polyatomic ion : a group of (covalently) bonded nonmetals that form a charge. • Act as a single ion in an ionic bond • Have special names that DO NOT CHANGE • You need to write down the polyatomic ions and their names on an index card and DO NOT LOSE IT!!! • You will use your list on all quizzes and tests!

15. Carbonate CO3-2 Chromate CrO4-2 Dichromate Cr2O7-2 Oxalate C2O4-2 Sulfate SO4-2 Sulfite SO3-2 PhosphitePO3-3 Phosphate PO4-3 Permanganate MnO4- Peroxide O2-2 • Ammonium NH4+ • Acetate C2H3O2- • Hypochlorite ClO- • Chlorite ClO2- • Chlorate ClO3- • PerchlorateClO4- • Cyanide CN- • Hydroxide OH- • Nitrite NO2- • Nitrate NO3- • Bicarbonate/Hydrogen Carbonate HCO3-

16. Writing Ionic Formulas - ternary • Write the cation – all metals (only polyatomic cation is ammonium: NH4+ ) • Write the anion – all nonmetals and polyatomic ions • If charges cancel – 1:1 ratio • If charges DO NOT cancel – drop & swap • You must use parenthesis if more than one polyatomic ion is present

17. Naming Ionic Formulas- ternary • Cation • Representative metals- element name • Transition (D-block) metals- element name and a Roman numeral to show charge • Polyatomic ion (NH4+)- regular name • Anion • Polyatomic ion- regular name • Nonmetal- change ending to -ide • Ex: • NaNO3- sodium nitrate • Cu2(SO4)3- copper (III) sulfate • NH4Cl- ammonium chloride

18. Practice • cesium nitrate • barium sulfite • aluminum hydroxide • strontium phosphate • ammonium sulfide • Iron(III) chlorite • Zinc(II) nitrite • Gold(III) carbonate • Silver(I) phosphite • Copper(I) acetate

19. COVALENT BONDbond formed by the sharingof electrons

20. Covalent Compounds • Covalent compounds result when nonmetals bond with nonmetals • Both nonmetalsshare their valence electrons to be happy – Octet Rule • Examples: • CO2 SCl2 • H2O CH4

21. Naming Covalent formulas • Use prefixes to show the # of atoms of each element in a covalent compound • 1 – mono 6 - hexa • 2 – di 7 - hepta • 3 – tri 8- octa • 4 – tetra 9 - nona • 5 – penta 10 – deca • 1st element – use prefixes only of the # of atoms is greater than 1 • 2nd element – use prefixes; change ending to – ide

22. Practice carbon dioxide • CO2 • N3F8 • Se4Br9 • S7O trinitrogenoctafluoride tetraseleniumnonabromide heptasulfur monoxide

24. Writing Covalent formulas • Use the prefix to identify how many of each nonmetal atoms are in each molecule • The prefix becomes the subscript. • Carbon TetrahydrideDisulfurHexachloride • CH4 S2Cl6

25. 1) Name the following covalent compounds: a) SiF4 b) N2S3 c) H3Br7 d) S5Br9 e) H2O • Write the formulas for the following covalent • compounds: a) diboronhexahydride b) nitrogen tribromide c) sulfur hexachloride d) diphosphoruspentoxide

26. Drawing Structures- Ionic • Electrons are TRANSFERRED Practice: • NaBr • AlCl3

27. Drawing Structures- Covalent • Electrons are SHARED • 1 pair= single bond • 2 pairs= double bond • 3 pairs= triple bond • Dot formulas and Structural formulas

28. Covalent Structure Practice • H2O CH4 • CO2 Cl2 • O2 N2

29. Diatomic Molecules • Always pair up with themselves in a pure sample • Allows them to be stable when there are no other elements to bond with • H2, N2, O2, F2, Cl2, Br2, I2

30. Metallic Bonds • Formed between two metals • One or two valence electrons (usually transition metals) • strong positive nuclei pull atoms close together, causing the outer e- orbitals to overlap • electrons delocalize; creates a ‘sea of electrons’ • electrons flow freely between atoms, this is why metals are good conductors of electricity

31. The remaining slides are for HONORS CHEMISTRY only

32. VSEPR • Valence Shell Electron Pair Repulsion • Predicts shapes of covalently bonded molecules • Copy the chart on p.263 of your book

33. Coordinate Covalent Bonds • one atom contributes both bonding electrons • once formed, no different from other bonds, just different source of electrons

34. Coordinate Covalent Ex: • Chlorate, ClO3-

35. Resonance Structures • shifting of electron pairs/bonds without shifting atoms

36. Resonance Ex: • Carbonate, CO3-2 • Ozone, O3