Biology 12 Name: _________________________________ Block: _________ Date: _______________

Unit 1 – Homeostasis; Chapter 2 – The Molecules of Cells

2.3 – The Chemistry of Water (p29-32) – STUDENT NOTES

Chemistry Review - the 3 types of chemical bonds important to biology are:

1) ____________ bond = the ___________ of electrons between a _________ ion and a ____________ ion

2) _____________ bonds = the ___________ of electrons between a _________ ion and a ____________ ion

There are 2 types of _____________ bonds

(a) in a ________________ bond, electrons are shared equally

(b) in a ________________ bond, electrons NOT equally shared.

3) _____________ bonds = is a weak polar bond ______________

___________________ molecules.

Some examples are:

Chemical Bonds form 2 types of compounds that are important to life:

____________________compounds and _______________ compounds

Today, our focus is on WATER:

Water is an ____________________ compound.

Water’s biological function/importance is due to its ______________________________

Water is a _________________________________.

How does the polarity of H2O produce H – bonding?

The oxygen atom is ________________ & _______________ charged. The hydrogen atom is ________________

& _______________ charged. Oxygen ________________ electron _______________ it creating a

Dipole.

The slightly positive __________ around the _____________ atom becomes attracted

to the slightly negative __________ around the _____________ atom of DIFFERENT water molecules

As water is a polar molecule, it has special or unique properties.

But first a note about HYDROPHILIC vs. HYDROPHOBIC substances:

Water is important to life!!! -- It has 5 unique properties – are all related to water being a polar molecule

One more quick review: Sodium Chloride = a salt made up of NaCl

A solute = salt =

A solvent = water =

Together: Solute + Solvent = ___________________

Special Property # 1: Water is a _____________________________________

Special Property # 2: Water is a _____________________________________

a)

b)

c)

Water molecules are:

Special Property # 3: Water is a _____________________________________

a)

Special Property #4: _____________Water is less dense than _______________ water

Why is this property important to living organisms?

Special Property #5: Water molecules can act as a __________ for hydrogen (H+) or hydroxide (OH-) groups

0 This makes water an important reactant for biochemical processes

HW and Review:

0 Textbook: 0 Ch2.3 Chemistry of Water p 29-320 Ch2.4 Organic Molecules p 32-330 Review questions p 56 Q#1-6, 41-48

0 Videos0 Bio12 – Biochem Playlist – videos #1 = 8

0 Water Lab Next Class