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The Chemistry of Life: Atoms and Molecules =
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Pure substances that cannot be broken down into simpler chemical entities by ordinary chemical reactions. Elements Periodic Table 112 known elements
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Major Elements Comprising the Biological Molecules of Living Things C arbonC arbon H ydrogenH ydrogen O xygenO xygen N itrogenN itrogen P hosphorusP hosphorus S ulfurS ulfur
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Other Major Elements of Living Things Calcium (Ca)Calcium (Ca) Potassium (K)Potassium (K) Chlorine (Cl)Chlorine (Cl) Magnesium (Mg)Magnesium (Mg)
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Some Important Trace Elements of Living Things Boron (B)Boron (B) Cobalt (Co)Cobalt (Co) Iron (Fe)Iron (Fe) Copper (Cu)Copper (Cu) Fluorine (F)Fluorine (F) Zinc (Zn)Zinc (Zn)
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An element is composed of atoms (0.1-1 nm in diameter) Atom cluster of small particles (proton, neutron, electron) Elements & Atoms
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Subatomic Particles Protons (p + ) Neutrons (n o ) Electrons (e - )
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Electron Shell Configurations of Atoms proton neutron electron hydrogen atom helium atom carbon atom 1p, 0n, 1e-2p, 2n, 2e- 6p, 6n, 6e-
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atomic number: number of p; #p = #e- 2 He 2e- and 2p He
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atomic mass (atomic wt.) : sum of masses of p+n He 2p + 2n, atomic mass = 4 4 2 He He p + n e-
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p = n = e- = Atomic number = Atomic mass = C Carbon Atom
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C12C13C14 stablestable isotopeunstable- radioactive isotope Isotope atoms that differ in the number of neutrons 12 6 C 13 6 C 14 6 C C
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Molecule Two or more atoms held together by chemical bonds OxygenO 2 NitrogenN 2 AmmoniaNH 3 Carbon DioxideCO 2 WaterH 2 O MethaneCH 4 GlucoseC 6 H 12 O 6
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Compound Binding two or more different kinds of elements together NaCl CH 4 C 6 H 12 O 6
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Ion An atom that has either gained or lost electrons such that it exhibits a net charge Na + Cl -
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Sodium (Na) Atom 11 P + 12 N o
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Sodium (Na + ) Ion 11 P + 12 N o +
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Chlorine (Cl) Atom 17 P + 18 N o
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Chloride (Cl - ) Ion 17 P + 18 N o _
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Some Examples of Ions HydrogenH + PotassiumK + FluorideF - CalciumCa +2 MagnesiumMg +2
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HydroxideOH - BicarbonateHCO 3 - NitrateNO 3 - PhosphatePO 4 -3 AmmoniumNH 4 + Acetate C 2 H 3 O 2 - Complex Ions
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Bond Types Bond Types: Ionic Covalent Hydrogen
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Ionic Bonds Transfer of electron 17 P + 18 N o 11 P + 12 N o
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Covalent Bonding: Covalent Bonding: electron sharing O H H
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C H H H H C H H H H
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Hydrogen Bonding Between Water Molecules Covalent bond Hydrogen bond
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Hydrogen Bonding Between Different Molecules
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Examples of Organic Molecules
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Properties of Water 1.High heat capacity-absorbs and releases large amounts of heat (land heats faster than water) 2.High heat of vaporization- sweat, cooling mechanism 3.Polarity solvent properties- universal solvent 4.Reactivity- hydrolysis and condensation (dehydration)
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Polarity of Water Molecules
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Chemical Reactions A B reactant product
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Chemical Synthesis A + B AB
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Chemical Decomposition AB A + B
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Chemical Rearrangement AB + CD AC + BD
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H 2 O OH - + H + OO HH H H + Water molecule [H 2 O] Hydroxyl ion [HO - ] Hydrogen ion [H + ] Decomposition of Water
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Acids HCL H + + Cl - Proton donor, i.e., they donate H + ions HCl is a strong acid with a pH 1-2
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Bases Na + + OH - NaOH NH 3 + H + NH 4 OH - + H + H 2 O HCO 3 +H + H 2 CO 3 Proton acceptor, i.e., they take up H+ ions NaOH is a strong base ~pH 12
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Neutralization HCl + NaOH H 2 O + NaCl
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Buffer- resists dramatic changes in pH; ex. tums, rolaids…buffers stomach acid
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pH Scale Neutral7 Acidic0-6 Basic (alkaline)8-14 Type of Solution pH Value 0-14
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Logarithmic scale pH Scale
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Inquiry 1.How many neutrons in 7 N? 2.Of the following pH’s which is most acidic? 3762 3. The symbols K, Na, C, and S are: 4. Which of the following are elements? water; sugar; table salt; the atmosphere 5. Which of the following are pure substances? wine; seawater; blood; iron 14
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