Biological Hierarchy Emergent properties

Levels of Biological Organization

Evolution Universal connection -DNA Diverse classification of organisms

Key pointsMatter- pure form is elements/compounds

essential elementstrace elements

96% CHON

Element properties- dependent upon structure

Electron configuration- electrons are involved in chemical behavior

Nuclear structure- isotopes/radioactive isotopes

Types of bonds in compounds affects properties Ionic

Covalent: polar/nonpolar

Intermolecular attractions: Hydrogen bonding, dipole-dipole, London Dispersion aka van der Waals forces

Chemical reactions Breaking bonds- requires energy Making bonds –gives off energy

Equilibrium- dynamic reactions- forward and reverse rates become equivalent

Water- unique molecule due to polarity and hydrogen bonding

4 important properties of water Cohesion of water molecules

Moderation of temperature

Solid ice floats on liquid water

Universal solvent

Overview of Acid/Base Chemistry

Hydrogen ion (H+) acids

Hydroxide ion (OH-) bases

Water – has dynamic equilibrium in which molecules dissociate at the same rate at which they are being reformed

A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other

The hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion (H+)

The molecule with the extra proton is now a hydronium ion (H3O+), though it is often represented as H+

The molecule that lost the proton is now a hydroxide ion (OH–)

pH- measure of the concentration of H+ ion

pH = - log [H+]

In aqueous solutions: [OH-][H+] = 10-14

© 2011 Pearson Education, Inc.

Ch. 3 - Water & Lifeater & Life

• For a neutral aqueous solution, [H+] is 10–7, so

pH = –log [H+]

pH = –(–7) = 7

pH Scale

Battery acid

Gastric juice, lemon juice

Vinegar, wine,cola

BeerTomato juice

Black coffee

Rainwater

Urine

SalivaPure water

Human blood, tears

Seawater

Inside of small intestine

Milk of magnesia

Household ammonia

Householdbleach

Oven cleaner

Basicsolution

Neutralsolution

Acidicsolution

0

1

2

3

4

5

6

7

8

9

10

Neutral

[H+] = [OH]

Incr

easi

ngl

y B

asic

[H+]

< [

OH

]

Incr

easi

ngl

y A

cid

ic

[H+]

> [

OH

]

H+H+

H+

H+H+

H+

H+

H+

OH

OH

H+

OH

H+

OH

OH

OHOH

H+H+

H+

H+

OHOH

OH

OH OHOH

OHH+

11

12

13

14

BuffersThe internal pH of most living cells

must remain close to pH 7Buffers minimize changes in

concentrations of H+ and OH– in a solution

Most buffers consist of an acid-base pair that reversibly combines with H+

Buffer in Blood

The bicarbonate ion isn't a very strong acid or base. The direction it goes depends on the solution it is in.

CO2

CO2 + H2O H2CO3

H+ + HCO3

H+ + CO32 HCO3

CaCO3 CO32 + Ca2+

H2CO3