1. The Chemical Basis of Animal Life
Chapter 2

2. Chemistry
The branch of science dealing with composition of substances and reactions among these substances.
A knowledge of chemistry is essential for understanding the structure and function of animals because body functions involve chemical changes.

3. Matter Matter: is anything that occupies space and has mass.
Solids – Liquids – Gases
Matter has many properties.
PHYSICAL
different densities, melting points, boiling points, freezing points, color or smells.
CHEMICAL
what elements combine with each other in reactions.
Matter has many properties. It can have PHYSICAL properties like different densities, melting points, boiling points, freezing points, color or smells. There are also CHEMICAL properties that define matter. Like what elements combine with each other in reactions. Matter can combine in the same ways, physically and chemically.

4. Matter Matter includes all solids, liquids and gases
Matter is composed of elements which make up mass
Currently, 92 naturally occurring elements
~ 15 found in most animals and 4 (C,H,O,N) account for ~ 97% of animal’s body weight
A remaining ~ 3% are Ca, P, and K

5. Matter is composed of elements
Elements: chemical substances that ordinary chemical reactions cannot break down into simpler units.

6. ATOMS
Atoms atoms everywhere. Don't laugh, it's true. There are always atoms around unless you are inside of a vacuum. There are different types of atoms, one for each element. There are even different kinds of atoms for each element called IONS. You'll understand what we mean in a second.
We also introduce you to what happens when atoms combine. There are millions of ways atoms bond and make billions of COMPOUNDS. Don't know where to start? Start with atomic STRUCTURE and learn what is inside of an atom.

7. Atoms
Atoms are the smallest parts of an element that can enter into a chemical reaction.

8. Structure of Atoms Nucleus contains (+)protons and neutral neutrons
Atoms are composed of
nucleus and electron cloud
Nucleus
contains (+)protons and neutral neutrons
Electron cloud
contains (-) electrons

9. Atomic Number
The atomic number is equal to the # of protons in an atom
Oxygen At# = 8
Carbon At# = 6
Hydrogen At# = 1
Nitrogen At#= 7
Calcium At # = 20

10. Atomic Mass Atomic Mass = # of protons + # of neutrons
Oxygen = At. Mass of 16
Carbon = 12
Hydrogen = 1 (has no neutrons)
Nitrogen = 14
ISOTOPES: Same atom but has different atomic weight due to + or – neutrons
Carbon 13 has 7 neutrons instead of 6 (stable does not break down
RADIOISOTOPES
Unstable isotopes. 14C release small particles and energy.

11. Electron Shells Electrons are arranged in energy shells
Seven possible shells
Each shell can only hold a certain # of electrons
The nearest to the nucleus never has more than two.
The 2nd and 3rd hold up to eight electrons.

12. Chemical Compounds in Living Things
In varying combinations, the elements carbon, hydrogen, oxygen, and nitrogen make up practically all the chemical compounds in living things.

13. Compounds and Molecules
Water is a compound H O 2

14. Compounds
Compounds are composed of 2 or more elements chemically united in fixed portions.
ie. Water has 2 Hydrogen atoms and 1 Oxygen atom

15. Molecules Compounds of atoms held together by covalent bonds Covalent
Atoms share outer shell electrons with other atoms
i.e. O2

16. Hydrogen Bonds
Hydrogen gains a slightly positive charge as it is drawn toward another atom and leaves a proton behind.
Hydrogen bond is weak

17. Ionic bonds
Atoms gain or lose electrons in outer most shell creating a charge
A charged atoms is called an ion

18. Acids, Bases, and Buffers
Electrolytes conduct electricity in a solution
Acid –releases hydrogen (H+) ions in water
Base – releases hydroxide
ions (OH-) in water

19. Acids, Bases, and Buffers
pH – the measure of acidity or alkalinity of a substance
Range from 0-14
0 = Strong ACID
14= Strong BASE
7 = neutral

21. The pH scale and pH values of various aqueous solutions
Increasingly Acidic
[H+] > [OH–]
Increasingly Basic
[H+] < [OH–]
Neutral
[H+] = [OH–]
Oven cleaner 1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH Scale
Battery acid
Digestive (stomach)
juice, lemon juice
Vinegar, beer, wine,
cola
Tomato juice
Black coffee Rainwater
Urine
Pure water
Human blood
Seawater
Milk of magnesia
Household ammonia
Household bleach
Figure 3.8

22. Two types of compounds ORGANIC INORGANIC Those that contain carbon
Those that do not contain carbon
INORGANIC

23. Inorganic Compounds Primarily those that do not contain carbon.
Exception is carbon dioxide
Water and minerals are both inorganic
Living things contain a great many inorganic compounds
The compounds that make up bones and form salts are inorganic

24. Organic Compounds
Organic compounds contain carbon

25. Why is carbon so special?
Carbon is a unique element because of its remarkable ability to form covalent bonds that are strong and stable.
Carbon has 4 electrons in its outer shell; thus, it must share 4 electrons by covalent bonding – either with single or double bonds.
This allows carbon to form chains and rings

26. Carbon Atom
Carbon has 4 electrons in outer shell - - - - - -

27. Hydrocarbons
Are organic molecules that contain only carbon and hydrogen (most are in a linear arrangement)
Form the framework of all organic molecules
H H H H H H H
H-C-C-C-C-C-C-C-H

28. Compounds of Life carbohydrates lipids proteins nucleic acids
The four groups of organic compounds found in living things are :
carbohydrates
lipids
proteins
nucleic acids