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Bonding

Bonding. REVIEW. Valence electrons: Electrons in highest occupied energy level Can use electron dot structures to show valance electrons What would be the electron dot structure for Na? Cl? Ne?. Review. Octet Rule: Atoms loose or gain electrons to have a full outer energy level Bonding!!.

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Bonding

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  1. Bonding

  2. REVIEW • Valence electrons: Electrons in highest occupied energy level • Can use electron dot structures to show valance electrons What would be the electron dot structure for Na? Cl? Ne?

  3. Review • Octet Rule: Atoms loose or gain electrons to have a full outer energy level • Bonding!!

  4. Bonding • Ionic Bonds: Anions and cations attract each other • Covalent Bonds: Atoms share electrons • Metallic Bonds: Free floating valance electrons around positive charge metal ions

  5. Ionic Bonds • Cations: Loss of valence electrons to produce a positively charged ion with stable octet electron configuration Na Na+ Ne Mg Mg2+

  6. Ionic Bonds • Cations: Loss of valence electrons to produce a positively charged ion with stable octet electron configuration Na 1s22s22p63s1 Na+ 1s22s22p6 Ne 1s22s22p6 Mg 1s22s22p63s2 Mg2+ 1s22s22p6

  7. Ionic Bonds • Anions: Gain of valence electrons to produce negatively charged ion with stable octet electron configuration Cl Cl- Ar O O2- Ne

  8. Ionic Bonds • Anions: Gain of valence electrons to produce negatively charged ion with stable octet electron configuration Cl 1s22s22p63s23p5 Cl- 1s22s22p63s23p6 Ar 1s22s22p63s23p6 O 1s22s22p4 O2- 1s22s22p6 Ne 1s22s22p6

  9. Ionic Bonds

  10. Ionic Bonds • What would happen if Mg combined with Cl?

  11. Ionic Bonds • Formula Unit: the lowest whole-number ratio of ions in an ionic compound. 1Na: 1Cl  NaCl What would it be for magnesium chloride?

  12. Ionic Bonds • Compound Properties: • Solids • Repeating crystal structure • Stable • High Melting Point

  13. Covalent Bonds • Holds molecules together • (through sharing valance electrons) • Diatomic molecule: has ONLY 2 atoms • Molecular formula: shows how many atoms of each element are in a molecule • How is this different from a formula unit?

  14. REVIEW! • Covalent bonds are made so atoms can have a full outer valence shell through sharing electrons • OCTET RULE

  15. Covalent Bonds • Three types of covalent bonds: • Single: 1 pair of electrons are shared • Double: 2 pairs of electrons are shared • Triple: 3 pairs of electrons are shared

  16. Covalent Bonds • Single Covalent Bonds • Electron dot structure: Shows VALENCE electrons as dots • Structural formula: Shows SHARED electrons as line H-H

  17. Covalent Bonds • Single Covalent Bonds: • Draw the electron dot structure and structural formula for: Electron Dot For Each AtomElectron Dot For MoleculeStructural Formula H2O F2 NH3 CH4 Unshared/Lone Pair: valence electrons not involved in bond

  18. Covalent Bonds • Double and triple bonds • Draw the electron dot structure and the structural formula for: Electron Dot For Each AtomElectron Dot For MoleculeStructural Formula O2 N2 CO2 CO

  19. Covalent Bonds • Polar covalent bond: electrons are not equally shared Due to electronegativity!

  20. Covalent Bonds • Molecule Properties: • Low melting and boiling points • Liquid or gas • No ions and No Charge

  21. Attractions Between Molecules • Van der Waals Forces: • Dipole interactions: positive region of one polar molecule is attracted to negative region of another polar molecule • Dispersion forces: random electron motion in one nonpolar molecule effects the electron motion in a neighboring nonpolar molecule

  22. Attractions Between Molecules • Hydrogen Bonds: A hydrogen covalently bonded to a very electronegative atom weakly bonds to an unshared pair of electrons on another electronegative atom

  23. Review: Types of Attractions Strongest Ionic Bond Covalent Bond Hydrogen Bond Dipole Interactions Dispersion Forces Weakest

  24. Why do ionic compounds have higher melting points than molecules? Ionic Compounds have to break an ionic bond to melt. Molecules have to break a hydrogen bond, dipole interaction, or dispersion force to melt.

  25. Organic MoleculesBiology Review! • Covalent Bonds • Polymers: large molecules made by repeating subunits • DNA • Protein • Carbohydrates • Made possible by Carbon

  26. Organic Molecules • DNA • Subunit: Nucleotide

  27. Organic Molecules • Protein • Subunit: amino acids

  28. Organic Molecules • Carbohydrates • Subunits: Saccharides (sugars)

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