BiologyBiology

Ms. PetrucciBiology

Chapter 2: Chemistry of LifeChapter 2: Chemistry of Life• Vocabulary

• 2-1

◦ Atom

◦ Nucleus

◦ Electron

◦ Element

◦ Isotopes

◦ Compound

◦ Ionic Bond

◦ Ions

◦ Covalent Bond

◦ Molecule

◦ Van der Waals forces

• 2-2◦ Cohesion◦ Adhesion◦ Mixture◦ Solution◦ Solute◦ Solvent◦ Suspension◦ pH Scale◦ Acid◦ Base◦ Buffer

• 2-3o Monomero Polymero Carbohydrateo Monosaccharideo Polysaccharideo Lipido Nucleic Acido Nucleotideo Ribonucleic Acid (RNA)o Deoxyribonucleic Acid (DNA)o Proteino Amino acid

• 2-4o Chemical Reactiono Reactanto Producto Activation Energyo Catalysto Enzymeo Substrate

The Blue PlanetThe Blue Planet

Water BasicsWater BasicsWater, H2O, is made of two hydrogen

atoms bonded covalently with one oxygen atom.

Can exist on Earth as a solid, liquid or gas depending on the temperature.

Covers 70% f the Earth’s surface.It is essential for lifeWater Cycle

WaterWaterBent molecule. This gives it unique

properties.

Hydrogen BondingHydrogen Bonding

Water and the Hydrogen BondWater and the Hydrogen Bond

• High surface tension

• Relatively high boiling point

• High heat capacity

• Adhesion

• Cohesion

• Density in solid state is less dense•Unique

Properties of WaterProperties of WaterUniversal solvencyPhases of water ◦ Solid◦ Liquid◦ Gas

Surface tensionCapillary ActionDensitySpecific Heat

Let’s Talk WaterLet’s Talk Water

Acid Base and pHAcid Base and pH

http://sv.berkeley.edu/showcase/flash/juicebar.html

Acids or Bases?Acids or Bases?ACID, BASE or NEUTRAL?

◦ Soda

◦ Soap

◦ Coffee

◦ Wine

◦ Water

◦ Grapefruit

Calculating pHCalculating pH

Acidic & Basic Solutions◦ All aqueous solutions contain H3O and OH- ions

Neutral solutions

Acidic solutions

Basic Solutions

pH◦ Measures the acidity/basicity of a solution.

pH = -log[H3O+]

[H3O+] = 10-pH

pOH- Measures the acidity/basicity of a solution.

pOH = -log[OH-][OH-] = 10-pOH

Try a calculation:Try a calculation:

pOH =- log [OH-]

= - log (1.3 x 10-2 M) = 1.9

pH = 14 – pOH

= 14.0 - 1.9

= 12.1

Practice Problems:Practice Problems:Fill in the missing information. 

[H+]= 4.18 x 10-8M

[OH-] = 

pH =

pOH =

acidic, basic, or neutral? _______________

[H+] =  [OH-] = 2.74 x 10-2M

pH =

pOH =

acidic, basic, or neutral? ______________

Your turn – What do you already Your turn – What do you already know?know?

What are mixtures (solutions, colloids and suspensions)?

Define a mixture in your own words & give 2 examples

MixtureMixture

A mixture is a combination of two or more substances where there is no chemical combination or reaction.

Mixtures combine physically in no specific proportions. They just mix.

Mixtures are classified as:◦ HOMOGENOUS/HETEROGENOUS◦ SOLUTIONS◦ COLLOIDS◦ SUSPENSIONS

Solutions, Colloids and SuspensionsSolutions, Colloids and Suspensions

ColloidsColloids

In a colloid the particles are mixed together but not dissolved.

The particles are relatively large and are kept permanently suspended.

A colloid will not separate upon standing.

The particles are constantly colliding, and this allows a colloid to scatter light – thus colloids often seem cloudy.

Colloids are heterogeneous or homogeneous mixtures of intermediate sized particles (between 1 nm and 1000 nm) and do not settle out.

ExamplesExamples

SolutionsSolutions

A solution is a type of homogeneous mixture formed when one substance dissolves in another.

It is the best mixed of all mixtures.

A solution always has a substance that is dissolved and a substance that does the dissolving.

The substance that is dissolved is the solute and the substance that does the dissolving is the solvent.

TypesTypes

ExamplesExamples

SuspensionSuspension

Suspension- a heterogeneous mixture in which the particles are large enough to be seen by a microscope or the unaided eye (eventually, they settle out of the mixture). Example: stirring a teaspoon of dirt in a glass of water.

Solution, Suspension or Colloid?Solution, Suspension or Colloid?

Finger paints

Mayonnaise

Sugar in Water

Muddy water

• Muddy water

• Italian Dressing

• Jell-O

• Sulfur vapor in air

Fun little flow chartFun little flow chart