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Chemical Bonds

Chemical Bonds. Chemical Bond. The interaction b/ atoms/ions that results in a decrease in potential energy of the system which hence becomes stable. Electron -dot (Lewis) s ymbols. Valence electrons are shown as dots around the symbols of the atoms .

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Chemical Bonds

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  1. Chemical Bonds

  2. Chemical Bond • The interaction b/ atoms/ions that results in a decrease in potential energy of the system which hence becomes stable.

  3. Electron -dot(Lewis) symbols Valence electrons are shown as dots around the symbols of the atoms. 1 2 13 14 15 16 17 18 H He:      LiBe B  C  N  O : F :Ne :            Na Mg AlSiPS:Cl  :Ar :    

  4. Types of bonds • Ionic • Covalent • Metallic

  5. IONIC BONDThe Electrostatic attraction forces happen b/ metal and nonmetal ions as a results of exchanging electrons.

  6. Ionic Bonds: One Big Greedy Thief Dog!

  7. Properties of ionic compounds -have crystalline structure formed of repeating units). -ions stay together as a result of attraction b/ oppositely charged ions. -The 3D structure of the crystalline is named as :lattice.”

  8. Properties of ionic compounds • Hard, brittle. • Relatively high melting and boiling points • Do not conduct the electricity when solid but do when molten or in aqueous solution (since the ions are free to move). • Are more soluble in water than other solvents

  9. Ex. • Write • Lewis (electron-dot) formula • Chemical formula of the compound formed b/ Mg and O.

  10. Ex. • Write • Lewis (electron-dot) formula • Chemical formula of the compound formed b/ Al and S.

  11. NAMING IONIC COMPUNDS (P.100) • Name of the metal+ ionic name of the nonmetal Name of the metal+ name of the polyatomic ion

  12. NAMING IONIC COMPUNDS (P.100) Compounds Made with Variable Charged Metals Name of the metal (oxidation state of the metal in Roman numeral) + ionic name of the nonmetal Name of the metal (oxidation state of the metal in Roman numeral) + name of the polyatomic ion

  13. NAMING IONIC COMPOUNDS • NaBr • FeCl2 • Mg3N2 • Al4C3 • CuO • LiH • K3P • PbO2 • CuS

  14. NAMING IONIC COMPOUNDS • BaCO3 • Zn(NO3)2 • Rb3(PO4) • Fe(OH)3 • AgHCO3 CoI2 • CaSO4 NiCr2O7 • CuOH CrCrO4 • MnO2 KMnO4 • K2C2O4 Sr(ClO4)2

  15. COVALENT BOND:Happens b/ nonmetal atoms as a result of sharing electrons.

  16. Covalent Bonds

  17. Many interactions are present: • The attraction forces b/ the electrons and nucleus • Repulsion forces b/ the electrons • Repulsion forces b/ the nuclei

  18. NONPOLAR COVALENT BOND: The shared electrons are attracted w/ an equal power by both atoms in the bonding. H2, Cl2,Br2,Cl2,O2,N2

  19. Oxygen Atom Oxygen Atom Oxygen Molecule (O2)

  20. H2, Cl2:

  21. POLAR COVALENT BOND: The shared electrons are NOT attracted w/ an equal power by the atoms in the bonding. H2O,HF, HCl,NH3,CH4

  22. Electronegativity and bond polarity • The sharing of electrons in HF is unequal: the fluorine atom attracts electron density away from the hydrogen(the bond is thus a polar covalent bond) • The H-F bond can thus be represented as: The ‘ δ+' and ' δ -' symbols indicate partial positive and negative charges. The arrow indicates the "pull" of electrons off the hydrogen and towards the more electronegative atom

  23. The bond gets polar as the difference in the electronegativities of the atoms bonded increases.

  24. HCl:

  25. Bond energy • bond energy (E) is the measure of bond strength in a chemical bond. It is the heat required to break one mole of gaseous molecules into their individual gaseous atoms. (Bond energy)

  26. Screen clipping taken: 2/24/2013, 1:39 AM Bond energy

  27. Bond energy • Strong interactions have greater bond energies than that of the weak interactions. Ar(s) + 6.4 kJ  Ar(g) H2O(s) + 43.9 kJ  H2O(g) H2O(g) + 463.4 kJ  2H•(g) + OH•(g)

  28. Bond length Bond energy 154 pm 346 kJ/mol C C 134 pm 602 kJ/mol C C 120 pm 835 kJ/mol C C Bond length:The average distance b/ the nuclei of the atoms when the attraction and repulsion forces b/ the atoms are balanced.

  29. Bond length: C-C > C=C > C≡C Bond energy: C-C < C=C < C≡C

  30. Dublet(duet) Rule:Completion of valence electron number to 2 when atoms make bonds in order to reach the stability of He (H,Li). Octet Rule:Completion ve number to 8 when the atoms make a bond in order to reach the stability of Noble gases. (O,N,F,C,Cl,Br,I,P,S…)

  31. Atoms that are out of duet and octet rules: Be,B

  32. Naming covalent compounds • (prefix to indicate the number of 1st nonmetal+name of 1st nonmetal) + (prefix to indicate the number of 2nd nonmetal+ ionic name of second nonmetal)

  33. Naming covalent compounds • For you own information, here is some other generally useful information: • Roman Numerals • I = 1; II = 2; III = 3; IV = 4; V = 5; VI = 6; VII = 7. • Prefixes: • mono = 1; di = 2; tri = 3; tetra = 4; penta = 5; hexa = 6; hepta = 7; octa = 8.

  34. Naming covalent compounds • N2O3 • N2 O5 • Cl3F • Cl2O7 • Cl2O • PCl3 • SF4 • P2S3

  35. Naming compounds including polyatomic ions only • Name of 1st polyatomic ion + Name of 2nd polyatomic ion

  36. Naming covalent compounds • (NH4)3PO4 • (NH4)2SO4 • (NH4)2S • NH4Cl • (NH4)2CO3

  37. •• •• Cl H H Cl • • + • • •• •• Bond formation Notice that each atom has one unpaired electron!!!!!

  38. •• H Cl • • •• Lone pair electrons Bonding electrons Cov. Bond and lone (non-bonding) electrons: LEWIS formula!!!

  39. HCl

  40. WARNING!!!!!!!!!!!! All diatomic molecules have a linear geometry…

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