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Higher Level Class Monday, May 5 7:00 pm Class 3’s classroom 4 th period d-block elements!! 

Higher Level Class Monday, May 5 7:00 pm Class 3’s classroom 4 th period d-block elements!! . Bonding. 56-58, 62-70, 165-168, 358-360. chemical bond : strong electronic attraction between atoms decreases the P.E. of an atom, makes it more stable only the valence electrons are involved!.

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Higher Level Class Monday, May 5 7:00 pm Class 3’s classroom 4 th period d-block elements!! 

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  1. Higher Level Class • Monday, May 5 • 7:00 pm • Class 3’s classroom • 4th period d-block elements!! 

  2. Bonding 56-58, 62-70, 165-168, 358-360

  3. chemical bond: strong electronic attraction between atoms • decreases the P.E. of an atom, makes it more stable • only the valence electrons are involved!

  4. Bond type depends on electronegativity (electron affinity) • very different electronegativities: ionic • one metal, one non-metal • both very high: covalent • two non-metals • both low: metallic • one or more metals

  5. Ionic Bonds • metal (low electroneg.) + non-metal (high electroneg.) • Array of positively and negatively charged ions • held together by electrostatic attraction • ions are isoelectronic to noble gases– have the same electron structure as a noble gas

  6. 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…

  7. Cl sodium and chlorine • sodium transfers its electron to chlorine Na

  8. Polyatomic ions: most covalently bonded, but have an overall electronic charge

  9. Naming Ionic Compounds • chromium(III) hydroxide • copper(II) fluoride • Ca3(PO4)2 • calcium phosphate • anion ending …ide • Cr(OH)3 • CuF2 • Ca2+ PO43-

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

  11. Properties of Ionic Compounds • hard • brittle (break easily) • solid • high melting/boiling points • do not conduct electricity as solids • conduct electricity when dissolved in water (aq) or molten (melted into a liquid) - electrolyte • more soluble in water than in other solvents

  12. Covalent Bonding • two 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-

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

  14. 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)

  15. 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 needs one e- • Nitrogen?

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

  17. Double Bond • sharing two pairs of electrons • bonds more strongly than a single bond • structural hybrid Lewis O C O O C O O C O

  18. Triple Bond • Strongest N N N N N N

  19. Drawing molecule diagrams • Decide how many bonds each atom makes. • The central atom is the one that makes the most bonds. • Draw with single bonds • Calculate remaining electrons • Use remaining electrons

  20. HCN (hydrogen cyanide) • C=4, N=3, H=1 • HCO2- (methanoate ion) • H=1, C=4, O=2

  21. HF NH3 CH4 CF4 NO2- CHCl3 NH4+ H2CO SeF2 Draw structural, hybrid and Lewis structures

  22. Length and Strength of Bonds single doubletriple longestshortest lowestenergyhighest energy

  23. covalent bonds holding atoms together in a molecule = strong • forces between molecules = weaker • covalent molecules are easily separated from one another • soft solids • do not conduct electricity • more soluble in non-polar solvents than in water • low melting/boiling points (liquid or gas at r.t.p.)

  24. sometimes, a solid lattice is held together with covalent bonds • covalent network (giant covalent structures): very hard, very high melting/boiling points

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