The Chemistry of Life

Chapter 2

Atoms

• matter is anything that fills space

• atom-the smallest unit of matter

• nucleus-center of the atom

AtomsParticle Charge Location Weight

Proton + Nucleus 1

Neutron 0 Nucleus 1

Electron - ElectronCloud

0

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Atoms

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CCarbon12.011

Atomic Number = # of protons (or electrons)

Symbol

Name

Average Atomic Mass = protons + neutrons

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• element-pure substance that consists of one type of atom

Isotopes• Isotopes – atoms of the same element that

contain different numbers of neutrons.– Ex: C-12, C-13, and C-14

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Chemical Compounds• Compound – a substance formed by the

chemical combination of two more elements.– Example: H20, NaCl

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2 Types of Chemical Bonds

Covalent Bonds• A covalent bond forms when two atoms share

electrons– Forms molecules like water

water (H20)

Ionic Bonds

• When an atom loses or gains electrons, it becomes electrically charged

• Charged atoms are called ions• Ionic bonds are formed between oppositely charged

ions

The Water Molecule• Polar molecule – has a

positive and negative end because electrons aren’t shared evenly.

•Allows it to form hydrogen bonds

Solutions

• Solution – mixture in which all components are evenly distributed.– Solvent – does the dissolving (water)– Solute – gets dissolved (Kool-Aid)

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H2O-->H+ & OH-• H+ = Hydrogen ion

• in excess= acid

• OH- = Hydroxide ion

• in excess= base

Acids, Bases, and pH

• pH scale– measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14

Acids, Bases, and pH• Acids – form H+ ions in solution, pH less than

7. (ex: stomach acid)

• Bases – form OH- ions in solution, pH greater than 7. (ex: oven cleaner)

• Buffers – chemicals that prevent sudden changes in pH.

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Carbon!

• Organic compounds – contain carbon and are associated with living things.

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Organic Polymers• Polymers – macromolecules made of

repeating units called monomers.

• Four types: carbohydrates, lipids, nucleic acids, proteins.

Polymer

Monomers

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Carbohydrates• Carbohydrates – compounds made of

carbon, hydrogen, and oxygen in a ratio usually 1 : 2 : 1.– Energy source!!!– Ex: sugars, starches, glycogen, cellulose– Monosaccharides (monomer) (glucose)– Polysaccharides (polymer) (starch)

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Carbohydrates

Lipids• Lipids – made of mostly carbon and

hydrogen atoms.– Fats, oils, waxes– Three fatty acids and a glycerol– Store energy, make membranes, waterproof

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Lipids

Nucleic acids• Nucleic acids – contain hydrogen, oxygen,

carbon, nitrogen, and phosphorus.– Carry genetic information– Monomers = Nucleotides– Ex: DNA and RNA

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Proteins• Proteins – contain carbon, hydrogen,

oxygen, and nitrogen.– Form bones/muscles, transport substances, fight

disease, control reactions, regulate cell processes.

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–Monomers = amino acids

Proteins

–Peptide bond – bond between amino acids.

Chemical Reactions

• chemical reaction: a process that changes one set of chemicals into another set of chemicals

CO2 + H2O → H2CO3

Reactants Products

CO2 + H2O → H2CO3 Reactants Products

Enzymes

• Enzymes – proteins that act as catalysts (speed up reactions).– Can be affected by temperature & pH– Don’t get changed in the reaction.

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Enzymes

See theanimation!

1. An organic catalyst is indicated by letter

2. An enzyme-substrate complex is indicated by letter. Substrate goes into the active site!

B

CA

D