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CHEMISTRY

CHEMISTRY. The Building Blocks of Biology. Matter. Anything that has mass and occupies space. Solid, Liquid, Gas. Elements. Biological Elements. N itrogen C arbon H ydrogen O xygen P hosphorous S ulfur. 96%. Elements. Atom = smallest unit of matter unique to a particular element.

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CHEMISTRY

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  1. CHEMISTRY The Building Blocks of Biology

  2. Matter • Anything that has mass and occupies space. • Solid, Liquid, Gas

  3. Elements

  4. Biological Elements • Nitrogen • Carbon • Hydrogen • Oxygen • Phosphorous • Sulfur 96%

  5. Elements • Atom = smallest unit of matter unique to a particular element. • (smallest “piece” of an element) • Molecule = union of 2 or more atoms. • Compound = union of 2 or more different atoms.

  6. Atomic Structure • Determines how atoms act. • Protons (+) • Neutrons (no charge) • Electrons (-) • Atomic # • Atomic Mass (Mass #) – an approximation. Nucleus Orbiting

  7. Cloud of negative charge (2 electrons) Electrons Nucleus Models of Atomic Structure

  8. Electron Shells • 1st Shell holds up to 2e- • 2nd Shell holds up to 8e- • 3rd Shell holds up to 8e-

  9. Which element is this?

  10. “Normally” • # Protons = # Neutrons = # Electrons • BUT, not always… • Isotopes – Atoms with variable #’s of Neutrons • Stable & Unstable • Ions – Atoms with variable #’s of Electrons

  11. Atoms “like” to do 2 things: • Be Balanced. • Fill their outer-most shells.

  12. “Valence” Electrons • Those electrons occupying an atom’s outer-most shell (its “Valence Shell”)

  13. Formation of Ions • Oxidation – Departure of an e- • Reduction – Gaining of an e- e-

  14. Bonding • Linking together atoms to form molecules… • Covalent Bonding • Ionic Bonding • Hydrogen Bonding • (Peptide Bonding)

  15. H H O O Covalent Bonding • Strong • Sharing of valence electrons • Non-Polar Covalent Bonds EQUAL SHARING H2 O2

  16. O H H Covalent Bonding • Strong • Sharing of valence electrons • Polar Covalent Bonds UNEQUAL SHARING H2O

  17. Because oxygen (O) is more electronegative than hydrogen (H), shared electrons are pulled more toward oxygen. d– This results in a partial negative charge on the oxygen and a partial positive charge on the hydrogens. O H H d+ d+ H2O Polar Covalent Bonds • Water…

  18. Ionic Bonding • Electrons are transferred (not shared) • Oxidation forms a Cation (+ charged). • Reduction forms an Anion (- charged). • Bond results from the attraction between ions of different charge…

  19. The lone valence electron of a sodium atom is transferred to join the 7 valence electrons of a chlorine atom. Each resulting ion has a completed valence shell. An ionic bond can form between the oppositely charged ions. – + 1 2 Cl Na Na Cl Na+ Sodium on (a cation) Na Sodium atom (an uncharged atom) Cl Chlorine atom (an uncharged atom) Cl– Chloride ion (an anion) Sodium chloride (NaCl) Ionic Bonding • Attraction between a Cation & an Anion.

  20. — + Hydrogen Bonding • Weak • A hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.

  21. H Water (H2O) O A hydrogen bond results from the attraction between the partial positive charge on the hydrogen atom of water and the partial negative charge on the nitrogen atom of ammonia. H  +  – Ammonia (NH3) N H H d+ + H Hydrogen Bonding

  22. Next…Water

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