1. Chapter 2 The Basics of Life

2. Matter, Energy, and Life
Matter: Anything that has mass and occupies space.
Energy: The ability to do work.
Two types of energy:
Kinetic energy - Energy of motion
Potential energy - Stored energy, available to do work

3. Law of Conservation of Energy
AKA The First Law of Thermodynamics
Energy is never created or destroyed.
Energy can be converted from one form to another, but the total energy remains constant.

4. Forms of Energy There are five forms of energy:
Mechanical energy – Movement
Nuclear energy – Atomic reactions
Electrical energy – Flow of charged particles
Radiant energy – Heat, light, x-rays and microwaves
Chemical energy - Energy in chemical bonds

5. What is the nature of matter?
Matter is made up of atoms & elements.
Atoms are the smallest unit of matter that exists alone & made up of:
Protons
Electrons
Neutrons
Elements are chemical substances made up of 1 kind of atom.
The Periodic Table (CP – p.1065, H – Back of book)

6. The Periodic Table of the Elements
Mass or weight
The Periodic Table of the Elements

7. Atomic Structure Atoms are composed of: Protons – “+” charged
Neutrons – no charge
Electrons – “-” charge

8. Atomic Structure

9. Elements Elements are chemical substances made up of one kind of atom.
Isotopes
Atoms of the same element that have different numbers of neutrons.
Atomic weight is isotope average in a mixture.
Mass number
The sum of protons and neutrons in the nucleus.

10. Isotopes of Hydrogen

11. Electrons Electrons occupy specific energy levels around the nucleus.
Energy levels hold specific numbers of electrons.
The first energy level can have up to 2 electrons.
Atoms seek to have a full outer energy level.
Atoms that have full outer energy levels are inert.
Other atoms seek to fill their outer energy levels through chemical bonds.

12. The Formation of Molecules
Molecules consist of two or more atoms joined by a chemical bond.
A compound is a chemical substance made of two or more elements combined in chemical bonds.
The formula of a compound describes the nature and proportions of the elements that comprise the compound.
H2O

13. Molecules and Kinetic Energy
Molecules are constantly in motion.
Temperature is a measure of the average speed of the molecules in a substance.
The greater the speed, the higher the temperature.
Measured in Fahrenheit, Celsius or Kelvin
Heat is a measure of the total kinetic energy of molecules.
Measured in calories (amount of heat that will raise 1g of water 1 degree Celsius).
Heat and Temperature are related.
Add heat energy to a substance and the molecules will speed up, and the temperature will rise.

14. Ionic Bonds The attraction of oppositely charged ions.
Ions are atoms that gain or lose electron(s).
Cation - When an atom gives away an electron, therefore has a positive charge. (Na+)
Anion - When an atom accepts an electron, therefore, has a net negative charge. (Cl-)

15. Ionic Bonds When atoms gain or lose electrons, they become ions.
Two oppositely-charged ions attract each other and form an ionic bond.
Ions, due to their charge, dissolve readily in polar solvents. 15

16. Covalent Bonds Form by sharing electrons.
The sharing of electrons cause the outer energy levels to overlap.
Single, double & triple covalent bonds occur in nature.

17. Covalent Bonds

18. Hydrogen Bonds
The positive hydrogen end of one polar molecule is attracted to the negative end of another polar molecule.
This attraction is a hydrogen bond.
Hydrogen bonds hold molecules together.
Since they do not hold atoms together, they are not considered true chemical bonds.
Hydrogen bonds are very important in biology.
They stabilize the structure of DNA and proteins.
Water molecules can “stick” together with hydrogen bonds.

19. Water: The Essence of Life
H2O has special properties that make it an essential molecule for life.
This is a polar covalent bond.
- Notice how the “+” charge is
located at the H end.
- Why do you suppose that is?
- Because the H electrons are
pulled to the O and are ‘trapped’ in O’s orbit, keeping
them to the inside of the
molecule.

20. Acids, Bases and Salts
Acid - Ionic compounds that release hydrogen ions (H+) into a solution. A hydrogen atom without its electron is a proton.
Base - Ionic compounds that remove hydrogen ions from solution. The hydroxide ion (OH-) being negatively charged, removes positively charged H+ from solution.
Salt - Ionic compounds that do not release either H+ or OH- when dissolved in water. However, they are generally the result of the reaction between an acid & a base in solution.

21. pH A measure of hydrogen ion concentration
Solutions with high hydrogen ion concentrations
Have low pH
Are acidic
Solutions with low hydrogen ion concentrations
Have a high pH
Are basic
There is a 10-fold difference in hydrogen ion concentration between solutions that differ by one pH unit.
A solution with pH 4 has ten times as many hydrogen ions as a solution with pH 5.

22. The pH Scale A measure of hydrogen ion concentration
A solution with pH 4 has ten times as many hydrogen ions as a solution with pH 5.