Chemicals of LifeA Unit on Biochemistry

Important terms:Atoms:

Basic building block of matter.

Composition of an atom:Made up of three subatomic particles:

Protons + in the nucleus

Neutrons neutral in the nucleus

Electrons --- electron shell

Elements: Substance made up of

all one type of atom.

Six most common elementsfound in living organisms:

C, H, N, O, P, S

hyperlink

http://www.youtube.com/watch?v=DYW50F42ss8

Molecules/compounds: Two or more atoms bonded together to create a new substance with new properties..

Molecules/compounds:

Two or more atoms bonded together to create a new substance with new

properties.

Example: NaCl /Sodium Chloride

Sodium

White crystalSolid

Explosive in water

Chlorine

Green GasVery poisonous

Sodium Chloride

White crystalSolid

Not explosiveNot poisonous

Table Salt

Most common compoundsin a living organism:

CarbohydratesLipidsProteinsNucleic AcidsWater

Two types of compounds:

Inorganic compounds: Do not contain carbonCan not be decomposed

Must be recycledExamples:

Sand, glass, styrofoamSoil, rocks, metals and water

Inorganic Compounds found in all living

organisms:

WATER

Water: H2O1. Made up of two hydrogen atoms bonded to one oxygen atom.

2. Atoms bond to form an angular molecule

3. Water is classified as a polar molecule.

Polar because like the Earth or a bar magnet it has a partial positive and a partial negative end.+

-

One of the most important rules in biology is that:

Opposites attract:

Therefore, one molecule of water’s positive end is attracted to another molecule of water’s negative end giving water many unique properties. Weak Hydrogen bonds hold the molecules together.

+ -+ -

Water’s unique characteristics:-1. Water is an inorganic molecule

-Contains no carbon-2. Water covers 75% of the Earth’s surface

-3. Water makes up 70% to 80% of a living organism

-4. Water is made up of two hydrogen atoms and one oxygen atom

-5. Water forms an angular molecule

-6. Water is a POLAR MOLECULE-has a + and a – end

+

-

7. Water occurs in three phases-Solid -molecules have a small amount of energy -molecules have just a little movement (just vibrating against each other)-molecules are close together and held in place with hydrogen bonds.-Liquid -molecules gain some energy and some movement -Hydrogen bonds are broken -molecules begin to spread out-Gas -molecules gain a lot of energy - molecules have a lot of rapid movement (enough to escape the surface into the air as a gas )-molecules widely spaced out

PHASE DIAGRAM OF WATER

8. Water displays cohesion: Co=

together hesion or hesive =

to stick

Cohesion is the attraction between like molecules. (one water molecule attracted

to another water molecule).

This occurs due to the fact that water is a polar molecule and opposites attract.

+

-

+

-

9. Water displays adhesion

• Adhesion– is the tendency of certain dissimilar molecules to

cling together due to attractive forces.

The water molecules are attracted to the “sides” of the graduated cylinder causing the water to raise up on the sides.

Water forms a concaved meniscus.

The water molecules are attracted to the sides of the glass container.

10. Water expands when frozen.

When frozen, the water molecules slow down and due to their polarity they will line themselves up + to – end thus taking up more volume and lowering it’s density.

O

H H

..

O

H H H

HH

HO

O

Solid Liquid

Occupies more volume

Occupies less volume

11. Water is known as the UNIVERSAL SOLVENT:

It dissolves more substances than any other substance on Earth.

To dissolve means that the molecules of one substance are picked up and totally surrounded by water molecules.

Demo of salt dissolving In water.

Mini Experiment #1

What is cohesion?-waters

attraction to other water molecules

Mini Experiment #2:

Water Alcohol

Mini Experiment #3

Cup 1 Cup 2 Ice in water Ice in alcohol

Reason why this occurred?

Mini Experiment #4Substance Soluble/dissolves Insoluble/does not

dissolve

Salt

Sugar

Oil

Powder soap

Mini Experiment #5

Using the two terms you defined, adhesion and cohesion, explain why the water is able to travel down the string from position A to position B.

STRING DEMO

13. Due to its polarity, water is excellent at making two types of

mixtures

1. Suspensions

2. Solutions

What is a mixture:- 2 or more substances combined but not chemically.-each substance retains it’s own properties.-each substance can be separated from the other.

Examples???????

Suspensions:A substance is mixed with water and the 2 substances separate.

The less dense substance is “suspended above” the more dense substance.

Example: Oil and water

This happens because water is polar and oil is NONPOLAR

(no + or – ends)

Blood is a suspension:

Solutions:One substance dissolves into another substance.

Examples:Kool aidSalt water

Cytoplasm is a solution:

The Rule:Likes dissolves likes:

Polar substances dissolve other polar substances

Water dissolves salt

Nonpolar substances dissolve other nonpolar substances

Gasoline or lighter fluid dissolves oil

Parts of a solution:

Substance doing the dissolving. (water)Solute:

Substance being dissolved. (salt)

Solution: Created when the solute

DISSOLVES in the solvent. (salt water)

Aqueous solution: water is the solvent

Saline solution: salt is the solute

3 types of water solutions:

Acids, Bases and Neutral

Acids:A substance that releases +H ions

when dissolved in water.

Acidic Solutions:

HCl is Hydrogen Chloride

• HCl is Hydrogen Chloride– H is +1 and Cl is – 1 therefore it is neutral– Not dangerous to us and our tissues– When HCl is dissolved into water, the H and Cl

ions separate.

• HCl is now known as Hydrochloric Acid– It is now very dangerous to us and our tissues

Base:A substance that releases -OH

ions when dissolved in water.

Basic Solution:NaOH is Sodium Hydroxide

NaOH is Sodium HydroxideNa is +1 and OH is – 1 therefore it is neutralNot dangerous to us

When NaOH is dissolved into water, the Na and OH ions separate.

NaOH, sodium hydroxide is now very dangerous to us and our tissues

Neutral: A substance that release no +H

or –OH ions when dissolved in water

A substance that releases and equal amount of both the +H and the – OH ions and they cancel each other out.

OR

Neutral Solution:

pH Scale:

-measures the strength and weaknesses of an acid (%H+) and of bases (%OH-)

-based on a scale of 0 to 14

pH scale:

pH and common substances:

Neutralization Reaction:When an acid and a base of equal strength are mixed and cancel each other out creating a neutral substance.

HCl + NaOH ---- NaCl + HOHStrong Strong neutral neutral acid base no H or OH H = OH

Buffer:A substance which guards against shifts in the pH level.

Our blood is an example of a buffer. Blood uses extra H+ and OH- ions substances to help resist pH changes in our body.

Lab: Using Acid-Base Indicators

Indicator Test:-special chemicals that can show whether a substance is an acid, a base or is neutral.

-Two type of indicators:-pH paper: Used to determine the

strength or weakness of an acid or a base.

-litmus paper: Used to determine the presence of either or both H+ or –OH ions.

pH paper:

Litmus Paper:

-Two types of litmus paper.

-RED and BLUE

Litmus Paper:

Red Litmus Paper

- stays red when H+ ions are present. -turns blue when OH- Ions are present.

Blue Litmus Paper

- turns red when H+ ions are present. -stays blue when OH- Ions are present.

ItemResult of Test

Blue LitmusRedor

Blue

Red LitmusRedor

Blue

pH paperColor and

Number

Strong Acid, Weak Acid

Strong Base,Weak Base

1. Benedict’s solution