1. CHEMISTRY

2. Composition of Matter
Matter - Everything in universe is composed of matter
Matter is anything that occupies space or has mass
Mass – quantity of matter an object has
Weight – pull of gravity on an object

3. Elements
Pure substances that cannot be broken down chemically into simpler kinds of matter
More than 100 elements (92 naturally occurring)

4. 90% of the mass of an organism is composed of 4 elements (oxygen, carbon, hydrogen and nitrogen)
Each element unique chemical symbol
Consists of 1-2 letters
First letter is always capitalized

5. Atoms
The smallest particle of an element that retains all the properties of that element.
Properties of atoms determine the structure and properties of the matter they compose
Our understanding of the structure of atoms based on scientific models, not observation

6. The Nucleus 2 main regions: Central core & electron shell
Consists of positive charged protons and neutral neutrons
Nucleus is positively charged
Contains most of the mass of the atom

7. The Protons
All atoms of a given element have the same number of protons
Number of protons called/determines the atomic number
Number of protons balanced by an equal number of negatively charged electrons

8. The Neutrons
The number varies slightly among atoms of the same element
Different number of neutrons produces isotopes of the same element

9. Atomic Mass Protons & neutrons are found in the nucleus of an atom
Protons and neutrons each have a mass of 1 amu (atomic mass unit)
The atomic mass of an atom is found by adding the number of protons & neutrons in an atom

10. The Electrons
Negatively charged high energy particles with little or no mass
Travel at very high speeds at various distances (energy levels) from the nucleus

11. Electrons in the same energy level are approximately the same distance from the nucleus
Outer energy levels have more energy than inner levels
Each level holds only a certain number of electrons

12. Energy Levels Atoms have 7 energy levels
The levels are K (closest to the nucleus), L, M, N, O, P, Q (furthest from the nucleus)
The K level can only hold 2 electrons
Levels L – Q can hold 8 electrons (octet rule)

13. Periodic Table
Elements are arranged by their atomic number on the Periodic Table
The horizontal rows are called Periods & tell the number of energy levels
Vertical groups are called Families & tell the outermost number of electrons

15. Compounds Most elements do not exist by themselves
Readily combine with other elements in a predictable fashion

16. A compound is a pure substance made up of atoms of two or more elements
The proportion of atoms are always fixed
Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound

17. Molecules are the simplest part of a substance that retains all of the properties of the substance and exists in a free state
Some molecules are large and complex

18. Chemical Formulas
Subscript after a symbol tell the number of atoms of each element
H20 has 2 atoms of hydrogen & 1 atom of oxygen
Coefficients before a formula tell the number of molecules
3O2 represents 3 molecules of oxygen or (3x2) or 6 atoms of oxygen

19. The physical and chemical properties of a compound are different from the physical and chemical properties of the individual elements that compose it.

20. The tendency of elements to combine and form compounds depends on the number and arrangement of electrons in their outermost energy level
Atoms are most stable when their outer most energy level is filled & won’t react with other atoms.

21. Most atoms are not stable in their natural state
Tend to react (combine) with other atoms in order to become more stable (undergo chemical reactions)
In chemical reactions bonds are broken; atoms rearranged and new chemical bonds are formed that store energy.

22. Covalent Bonds
Formed when two atoms share one or more pairs of electrons

23. Ionic Bonds
Some atoms become stable by losing or gaining electrons. These atoms are called Ions.
Atoms that lose electrons are called positive ions.

24. Atoms that gain electrons are called negative ions.
Because positive and negative electrical charges attract each other ionic bonds form

25. States of Matter Atoms are in constant motion
The rate at which atoms or molecules in a substance move determines its state.

26. Solid Molecules tightly linked together in a definite shape
Vibrate in place
Fixed volume and shape

27. Liquids Molecules not as tightly linked as a solid
Maintain fixed volume
Able to flow and conform to shape of container

28. Gas
Molecules have little or no attraction to each other
Fill the volume of the occupied container
Move most rapidly
To cause a substance to change state, thermal energy (heat) must be added to or removed from a substance

29. Solutions

30. Solutions
A solution is a mixture in which 2 or more substances are uniformly distributed in another substance

31. Water is the universal solvent
Solute is the substance dissolved in the solution
Particles may be ions, atoms, or molecules
Solvent is the substance in which the solute is dissolved
Water is the universal solvent

32. Solutions can be composed of varying proportions of a given solute in a given solvent --- vary in concentration (measurement of the amount of solute)
A saturated solution is one in which no more solute can be dissolved.
Aqueous solution (water as solvent) are universally important to living things

33. Dissociation of water
Breaking apart of the water molecule into two ions of opposite charge (due to strong attraction of oxygen atom of one molecule for H atom of another water molecule)
H2O  H+ (hydrogen ion) + OH- (hydroxide ion)

34. Acids and Bases
One of the most important aspects of a living system is the degree of acidity or alkalinity

35. Acids
Number of hydrogen ions in solutions is greater than the number of hydroxide ions
HCl  H+ + Cl-

36. Bases
Number of hydroxide ions in solution is greater than the number of hydronium ions
NaOH  Na+ + OH-

37. pH Scale
logarithmic scale for comparing the relative concentrations of hydrogen ions and hydroxide ions in a solution
ranges from 0 to 14
Each pH is 10X stronger than next
e.g. ph 1 is 10 times stronger than ph 2

38. the lower the pH the stronger the acid
the higher the pH the stronger the base
pH 7.0 is neutral

39. Buffers Control of pH is very important
Most enzymes function only within a very narrow pH
Control is accomplished with buffers made by the body
Buffers keep a neutral pH (pH 7)

40. Buffers neutralize small amounts of either an acid or base added to a solution
Complex buffering systems maintain the pH values of your body’s many fluids at normal and safe levels