THE CHEMISTRY OF LIFE

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THE CHEMISTRY OF LIFE

• CHAPTER 2

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2.1 The Nature of Matter

• The basic unit of matter is an atom
• Atoms cannot be broken down
• Atoms are made up of subatomic particles
• Protonspositively () charged
• Neutronsno charge
• Electronsnegatively (-) charged

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Subatomic Particles

• Nucleus is made up of protons plus neutrons
• Protons and Neutrons also make up the mass of an
  atom.
• Electrons orbit the nucleus.

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Nitrogen (7P, 7N, 7E)
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Elements and Isotopes

• Elements are a pure substance that consist of
  just one kind of atom
• Examples
• Carbon C
• Hydrogen H
• Sodium - Na

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Elements and Isotopes

• Isotopes are atoms of the same element with a
  different number of neutrons
• Radioactive Isotopes- nuclei is unstable and will
  break down at a constant rate.
• Carbon-14 (6P, 6E, 8N) radioactive
• Carbon-13 (6P, 6E, 7N) nonradioactive
• Carbon-12 (6P, 6E, 6N) nonradioactive
• Used for determine age of rocks and fossils,
  treat cancer, kill bacteria, or as labels in
  organisms.

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Chemical Compounds and Bonds

• Compounds are substances formed by 2 or more
  elements.
• Ex. Water H2O, Carbon Dioxide CO2, and Salt-
  NaCl
• A molecule is the smallest unit of most
  compounds.
• There are two type of chemical bonds
• Ionic Bonds one or more electrons are
  transferred from one atom to another.
• Covalent Bonds electrons are shared between
  atoms.

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Ionic Bond
Sodium atom (Na)
Chlorine atom (Cl)
Sodium ion (Na)
Chloride ion (Cl-)
Transfer of electron
Protons 11 Electrons -11 Charge 0
Protons 17 Electrons -17 Charge 0
Protons 11 Electrons -10 Charge 1
Protons 17 Electrons -18 Charge -1
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Covalent Bond
Bonds can exist as Single, double, or triple
bonds
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Van der Waals Forces

• An attraction that forms between oppositely
  charged regions of nearby molecules.
• Ex. Geckos foot and a wall
• Charge is not as strong as ionic or covalent
  bonds.

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2-1 Section Assessment

• Describe the structure of an atom.
• Why do all isotopes of an element have the same
  chemical properties? In what ways do isotopes of
  an element differ?
• What is a covalent bond? An ionic bond?
• What is a compound? How are compounds related to
  molecules?

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2-2 Properties of Water

• Water is a polar molecule. That is, it has an
  uneven distribution of e- between the oxygen and
  hydrogen atoms

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Hydrogen Bonds

• Not as strong as covalent or ionic bonds.
• Water is cohesive and adhesive
• Cohesion- attraction between molecules of the
  same substance
• Ex. Water molecules
• Adhesion- attraction between molecules of
  different substances
• Ex. Water and glass

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Solution and Suspensions

• Mixture a material composed of two or more
  elements or compounds physically mixed
• Ex air, sand and water, salt and water

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Solution

• Solution mixture where particles are evenly
  distributed
• two parts
• -solute sub. that is dissolved
• -solvent does the dissolving

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NaCl Solution
Cl-
Cl-
Na
Na
Water
Water
Salt is an ionic compound. When placed in
Water, water separates and ions.
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Suspensions

• Suspension mixture of water and substances that
  do not dissolve
• -ex. sand and water, blood

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Acids, Bases, and pH

• H2O ? H OH-
• Water ? Hydrogen ion Hydroxide ion
• acid contain higher concentrations of H ions
  than pure water
• base contain lower concentrations of H ions
  than pure water

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pH Scale

• Used to indicate the concentration of H ions in
  a solution.
• 0?14/Acid?Base
• 7 is neutral

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2-2 Section Assessment

• Use the structure of a water molecule to explain
  why its polar.
• Compare acidic and basic solutions in terms of
  their H ion and OH- ion concentration.
• What is the difference between a solution and a
  suspension?

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2-3 Carbon Compounds

• Carbohydrates- Sugars and Starches
• Lipids- Fats and Oils
• Nucleic Acids- Nucleotides
• Proteins- Amino Acids

carbons structure has four valence electrons a
carbon atom can bond to other carbon atoms to
form chains or rings
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Carbohydrates

• Function- Main energy source for living things.
• Serves as a structural purpose in plants and some
  animals.

Starch
Glucose
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More Carbs

• Monosaccharides- single sugar
• Ex. Glucose, galactose, and fructose
• Polysaccharides- many sugars
• Ex. Starches, glycogen, and cellulose

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Lipids

• Lipids are made mostly from carbon, hydrogen, and
  oxygen
• Function- Store energy
• -some examples are fats, oils, and waxes
• -saturated no double bonds-butter
• -unsaturated has double or
• triple bonds olive oil

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Nucleic Acids

• nucleic acids contain carbon, hydrogen, oxygen,
  nitrogen, and phosphorus
• Nucleotides consists of
• 5-Carbon sugar
• Phosphate group
• Nitrogenous base

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Nucleic Acids

• Function of nucleic acids store and transmit
  hereditary or genetic information
• two types DNA and RNA

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Proteins

• proteins contain carbon, hydrogen, oxygen,
  nitrogen
• -building blocks amino acids
• - 20 different kinds

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Protein Structure
Amino acids
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Proteins

• Function of proteins
• control rate of chemical reaction
• regulate cell processes
• form bone and muscle
• transport substances
• fight disease

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2-3 Section Assessment

• Name four groups of organic compounds found in
  living things.
• Describe at least one function of each group of
  organic compounds.

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2-4 Chemical Reactions and Enzymes

• chemical reaction process that changes one set
  of chemicals into another
• -two parts
• reactants - enter reaction
• products - produced by reaction

an example of a chemical reaction CO2 H2O ?
H2CO3 carbon dioxide water yields carbonic acid
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Enzymes

• catalyst substance that speeds up a chemical
  reaction
• -enzymes are biological catalysts
• -enzymes speed up chemical reactions in cells

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Enzyme Action

• for a chemical reaction to take place, the
  reactants must collide with each other to break
  the bonds
• -substrates are what the enzyme breaks down or
  builds up
• -the site where an enzyme and substrate meet is
  called the active site

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