1. Chapter 3:
Part I Biochemistry

2. Matter: Anything that has mass and takes up space – can be solid, liquid or gas
Atom: Smallest unit of matter that cannot be broken down by chemical means

3. Parts of an atom:
Protons (+)
Electrons (-)
Neutrons (0)
Protons and neutrons are found in the nucleus
Electrons orbit electron clouds around the nucleus

4. Inner energy level holds two electrons
Other energy levels holds eight electrons
The number of electrons in the outer energy shell determines the chemical properties of the atom.

5. Using the periodic table:

6. Atomic number = # of protons
Atomic mass = # of protons + neutrons
If number of protons = number of electrons, atom is neutral (no charge)
Elements are arranged horizontally in order of increasing atomic number
Elements are arranged vertically according to the number of electrons in the outer shell

7. Isotopes: atoms that differ in their number of neutrons
Carbon has 3 isotopes:
Carbon 12 (most abundant)
Carbon 13
Carbon 14 (radioactive - unstable)

8. Atom is most stable when the outer shell is filled
Number of electrons in outermost shell = valence electrons
Ex: Helium – 2 electrons in 1st shell
Neon – 8 electrons in 2nd shell
Elements in last column of periodic table have filled outer shells – Noble gases
To become stable, atoms form bonds with other atoms

9. Molecules: A group of atoms held together by covalent bonds
Ex: O2 or CO2
Compound: A substance made of the bonded atoms of two or more different elements.
Ex: CO2 or C6H12O6

10. Chemical/molecular formula: shows kind and proportion of atoms of element/molecule
Ex: 5HCl 8C
14Fe 6H2O
C6H12O6 3CO2
Na+ N2

11. Structural formula: Shows the arrangement of atoms within the molecule

12. Types of bonds: ionic bonds, covalent bonds & hydrogen bonds
Ion – an atom that has an electric charge because it has gained or lost electrons
Ions with opposite charges (- or +) are attracted to each other and form an ionic bond.
Ionic bonds – the attractive force between two oppositely charged ions

13. Ionic Bonds

17. In covalent bonds, atoms share electrons
Animation

18. Solution – a mixture in which ions or molecules are evenly distributed in another substance
Some water molecules break apart to form ions
Hydronium (H3O+)
Hydroxide (OH-)
In water, the balance of these ions is equal
In solutions such as acids and bases, the number of hydronium and hydroxide is unequal

20. Acids are any compound that increases the number of hydronium ions when dissolved in water
HCl  H+ + Cl-
H20 and H+ combine to form H3O+

21. Bases are any compound that increases the number of hydroxide ions when dissolved in water (also called alkaline).
NaOH  Na+ + OH-

22. pH – a measure of how acidic or basic a solution is
Acid – pH 0-6
Base – pH 8-14
Neutral - 7

24. Buffers: a substance that reacts to prevent pH changesd in a solution – do so by taking up excess H+ or OH- ions.
Help maintain pH in blood, stomach acid, urine, and intestinal fluid – example of how your body maintains homeostasis!!!