Chapter 2: The Chemistry of Life

2-1 The Nature of MatterKey Concepts

What three subatomic particles make up atoms?

How are all of the isotopes of an element similar?

What are the two main types of chemical bonds?

2-1 The Nature of MatterAtoms

Building blocks of matterSubatomic particles: protons, neutrons, electrons

location charge

protons nucleus positive

neutrons nucleus neutral

electrons electron cloud negative

Atomic Structure

Elements and IsotopesElement-pure substance that consists entirely

of one type of atom

Isotope- atoms of the same element that differ in the number of neutrons they contain

Key concept: Because the have the same number of electrons, all isotopes of an element have the same chemical properties

Radioactive IsotopesSome isotopes are radioactive = their nuclei are

unstable and break down at a constant rate over time (half-life)

Can give off radiation (potentially dangerous)

Several uses in scienceGeology-rock and fossil agesMedicine-cancer treatments, bacteria killers

Tracers of movements inside organisms

Chemical CompoundsCompound-substance formed by the chemical combination

of two or more elements in definite proportions

Big idea: physical and chemical properties of a compound are usually very different from those elements from which it is formed!

Sodium = reacts explosively in water

Chlorine = poisonous greenish gas used to kill soldiers in WW1

Combined make salt! Essential for life!

Ex: water, salt

Chemical Bonds The main types of chemical bonds are covalent and ionic bonds!

Ionic Bonds Transfer(Gain or loss) of electrons Formed by ions of opposite charge Between Metals and Nonmetals RIGID, BRITTLE Ex: NaCl

Covalent Bonds Sharing of electrons Structure resulting is called a molecule Between two or more nonmetals FLEXIBLE! Ex: H20

Ionic is Stronger!

Ionic Bonding

Covalent Bonding

Van der Waals ForcesDifferent elements have different abilities to

attract electrons…so some atoms in a covalent bonds do not share electrons equally…so the rapid movement of electrons can create regions of a molecule that have tiny positive or negative charge

The slight attraction between oppositely charged regions of nearby molecules

Not as strong as covalent or ionic bonds

2-2 Properties of WaterKey Concepts

Why are water molecules polar?

What are acidic solutions?

What are basic solutions?

2-2 Properties of WaterThe water molecule

Polarity-The uneven distribution of electrons between oxygen and hydrogen atoms

Hydrogen BondsPartial positive and partial negative regions of

water molecules attract each otherCohesion-attraction between molecules of the

same substance (surface tension)Adhesion-attraction between molecules of

different substances (capillary actions)

Solutions and SuspensionsMixture- a material composed of two or more

elements or compounds that are physically mixed together but not chemically combined

Two mixtures of water possible1. solution2. suspension

SolutionsAll components are evenly distributed

Always a solute and solvent

Solute: the substance that is dissolved

Solvent: the substance in which the solute dissolves

Water’s polarity allows it to dissolve both ionic substances and other polar molecules, it is THE GREATEST SOLVENT ON EARTH!

SuspensionsMixtures of water and nondissolved material

Non polar molecules are insoluble in water…like dissolves like!

Ex: blood

Acids, Bases, and pHThe pH scale

1-14 (represents the concentration of H+ (hydronium ions) in solution)

Below 7 = acidic

Above 7 = basic

7 = neutral

AcidsDefinition: any compound that forms H+ ions in

water

Have high concentrations of H+ ions, pH values below 7.

Strong acids 1-3

BasesDefinition: any compound that forms OH-

(hydroxide) ions in water

Have lower concentrations of H+ ions, pH values above 7.

Strong bases 11-14

BuffersWeak acids or bases that can react with strong

acids or bases to prevent sharp, sudden changes in pH.

Example: blood pH buffering

2-3 Carbon CompoundsKey Concepts

What are the functions of each group of organic compounds?

2-3 Carbon CompoundsThe Chemistry of Carbon

Can bond with many elementsFour valence electronsFormation of single, double, or triple bonds

MacromoleculesMany molecules are so large that they are

known as macromolecules, which can have thousands or hundreds of thousands of smaller molecules!

Monomer- smaller units

Polymers-larger unit made up of monomers

Polymerization-formation of a polymer from monomers

Organic Compounds: Four Main Groups

1. Carbohydrates

2. Lipids

3. Nucleic Acids

4. Proteins

CarbohydratesMade up of carbon, hydrogen, and oxygen in 1:2:1 ratio

Living things use carbohydrates as their main source of energy. Plants and some animals also use carbohydrates for structural purposes.

Sugar types Monsaccharides

Glucose, fructose, ribose Disaccharides

sucrose Polysaccharides

Starch, glycogen. cellulose

Carbohydrates

LipidsMostly carbon and hydrogen atoms

Generally not soluble in water

Categories include fats, waxes, and oils

Lipids can be used to store energy. Some lipids are important parts of biological membranes and waterproof coverings.

Saturated, unsaturated, polyunsaturated

Lipids

Nucleic AcidsCarbon, hydrogen, oxygen, nitrogen, and

phosphorous

Made up of nucleotides

Nucleic acids store and transmit hereditary, or genetic, information.Two Kinds:

Deoxyribonucleic acid(DNA) and ribonucleic acid(RNA)

Nucleic Acids

Proteins Macromolecules containing nitrogen, carbon, hydrogen,

and oxygen.

Made up of amino acids

Some proteins control the rate of reactions and regulate cell processes. Some are used to form bones and muscles. Others transport substances into or out of cells or help fight disease.

Proteins have up to four levels of organization. 1. sequence of amino acids in a protein chain 2. a.a.’s within a chain can be twisted or folded 3. the chain can be folded 4. more than one chain can be orientated in space

Proteins

2-4 Chemical Reactions and Enzymes

Key Concepts

What happens to chemical bonds during chemical reactions?

How do energy changes affect whether a chemical reaction will occur?

Why are enzymes important to living things?

2-4 Chemical Reactions and Enzymes

chemical reaction: a process that changes, or transforms, one set of chemicals into another

reactants: the elements or compounds that enter into a chemical reaction

products: the elements or compounds produced by a chemical reaction

Chemical reactions always involve changes in the chemical bonds that join atoms in compounds

Chemical Reaction Example

Energy in ReactionsEnergy Changes

EndothermicAbsorption of energy

ExothermicRelease of energy

Activation EnergyEnergy needed to get a reaction started

Endo or Exo?

Enzymescatalyst-substance that speeds up the rate of a

chemical reactionBy lowering a reaction’s activation energy!

Enzymes speed up chemical reactions that take place in cells.

Enzyme Action

Regulation of Enzyme Activity

Factors that affect the activitytemperaturepH