Chapter 2: The Chemistry of Life

ATOMS Are the smallest particles of an

element that has all the properties of that element

They are the building blocks of matter

They are made up of smaller particles: protons, neutrons and electrons- arranged in a specific way.

Atoms continued… MOST STABLE (unlikely to react)

when outermost energy level is completely filled

Energy Levels- have a set maximum # of electrons

Ion= atom that has lost or gained electronsLose electrons= become positive ionsGain electrons= negative ions

Elements- a substance that cannot be broken down by chemical processes into

simpler substances

*Protons are positively charged

*Neutrons have no electrical charge

*Electrons are negatively charged and are located along the outside

Isotopes Different number of neutrons, but same

element  They have the same proton and electron

number!

Compound two or more elements bonded together

Ex. H2O, NaClCompounds that contain CARBON and HYDROGEN together are termed, ORGANIC compounds

Chemical BondsAre the attractions that hold 2

or more atoms together to form a compound.

Whenever a chemical bond is formed or broken, energy is either absorbed or released

Ionic Bonds the chemical bond formed from the

attractive force between ions with opposite charges = NO ELECTRICAL

CHARGE (electrons are lost by one element & gained by another)

2. Covalent Bonds bonds in which electrons are

NOT gained or lost, but shared.Co- cooperative (sharing) Ex. Water, carbohydrates, lipids, proteins

and nucleic acids all have covalent bondsTYPES of Covalent BONDSSINGLE- 2 electrons sharedDOUBLE- 4 electrons sharedTRIPLE- 6 electrons shared

 

Types of bonds

The units formed by covalent bonds are called molecules—most are made of atoms from different elements

Some are notEx. N2, O2

Polar Molecules Atoms do not share electrons equally  There is a slightly negative end and a slightly

positive endEx. Water is POLAR

  

Van der Waals Forces Intermolecular forces of attraction Weaker forces than ionic or covalent

bonds

Gecko example on page 39

Do section Assessment 2-1 #s 1-6

2-2 Properties of Water Solutions: a uniform mixture of two or

more substances Water solutions are important because all

of life’s chemical processes occur in solution Uniform- mixed evenly so parts cannot be

distinguished 2 Components (parts)

Solvent- dissolving substance found in greatest amount

Solute- Dissolved substance

Water = The Universal Solvent Why? Because of polarity- dissolves

polar molecules, ionic compounds

2 Properties of water besides having hydrogen bonds (which are

weak chemical attractions between hydrogen and other atoms)

1. Cohesion- “sticking together”: causes surface tension- a filmlike boundary forms on the surface of water

Adhesion: attraction of molecules of different substances

2. Expansion- water expands as it freezes Ice has a lower density than liquid water Ice floats on water D= m/v D>1= sink

D<1= float

Acids, Bases and Salts When ionic compounds are placed in water

forming a solution, the compound breaks apart and releases ions.

Acid- A compound that releases Hydrogen Ions (H+) in water

Base- A compound that produces Hydroxide ions (OH-) when dissolved in water

Salt- Compounds that yield ions other than hydrogen or hydroxide ions when in solution, are called salts

pH SCALE pH scale is the standard measurement

of the concentration of hydrogen ions (H+) present in a solution

p= “power H= hydrogen ion concentration

pH scale ranges from 0 to 14

0 7 14

ACIDS BASESNEUTRAL

2- 3 Carbon Compounds Carbon has 4 valence electrons. Can bind with

many elements and to each other. Organic Chemistry is the study of carbon and hydrogen compounds.

Most abundant elements in our body : Don’t CHNO: carbon, Hydrogen, nitrogen and oxygen

Macromolecules: large molecules are formed by a process called polymeriazation

Monomers + monomers + monomers= polymers

Four groups of organic compounds found in living things:

1. Carbohydrates: sugars starches and cellulose—living things use carbs as main energy source and structural purposes

Sugars: mono, di and polysaccacharide Animals use glycogen Plants use starch

2. lipids: fats, oils and waxes—Can be used to store energy, they are important parts of membranes and waterproof coverings.

3. nucleic acids: store and transmit hereditary or genetic information--- made of monomers called nucleotides

3 PARTS!!2 KindsDNA Deoxyribonucleic

acid RNA: ribonucleic acid

4. Proteins: made up of smaller units called amino acids (Amino because has an NH2 on one end and a –COOH on the other)

Very important: Protein Synthesis in cells

Functions: Defense(antibodies), movement(actin/myosin), Transport (hemoglobin), hair and nails (keratin)

2-4 Chemical Reactions and Enzymes Chemical Reactions: a process that

changes one set of chemicals into another set of chemicals They always involve the breaking of bond

in the reactants and the formation of new bonds in the products

Example ( Label the reactants and products) CO2 + H2O H2CO3

Energy in Reactions Energy is released or absorbed

whenever chemical bonds form or are broken

Chemical reactions that release energy often occur spontaneously. Chemical reactions that absorb energy will not occur without a source of energy.

Energy Releasing 2H2 + O2 2H2O

Energy Absorbing2H2O 2H2 + O2

Energy Releasing (Exothermic)

Activation Energy- the energy needed to get a reaction started

Energy Absorbing (Endothermic)

Catalyst: is a substance that speeds up the rate of a chemical reaction- they work by LOWERING the activation energy

ENZYMES are protein catalysts

Enzyme - Substrate Complex Substrate= reactant, substance to be

changed Active site= where the substrate

attaches