1. A Brief Overview of Chemistry
The Chemistry of Life
A Brief Overview of Chemistry

3. Periodic Table

4. Element: Substance consisting entirely of one type of atom.

5. Atom: Basic Unit of Matter
(smallest part of an element)

6. Parts of an Atom
Protons, Neutrons, Electrons

7. Nucleus
Nucleus: The central portion of an atom containing neutrons and protons

8. Outside nucleus
Electrons

9. Atomic Number The number of protons in the nucleus of the atom.
It is listed on the Periodic Table, in numeric order

10. Proton
Proton: Positively charged particle(s) found in the nucleus of an atom
Mass = 1

11. If you change the # of protons in an atom, you will have a different element…

12. Electron
Electron: A negatively charged particle(s) found orbiting around the nucleus of an atom
No mass
Electron cloud
Shells

13. Neutrons
Neutron: Neutral (no charge) particles found in the nucleus of an atom.
Mass = 1

14. # Protons = # Neutrons = # Electrons

15. Atomic Mass
Atomic Mass: Includes the protons & neutrons in the nucleus of an element.
#Protons + #Neutrons =
Atomic Mass

16. Isotope Change in the “expected” number of neutrons
The number of neutrons does NOT equal the number of protons

17. Isotope What is the atomic mass? What is the atomic number?
How many protons?
How many neutrons?

19. Radioactive Isotope Nuclei unstable
Breaks down at a constant rate over time
Radiation emitted can be dangerous
Often used in determining the age of various things (i.e. fossils & rocks)
The atomic mass is the average mass of all the known isotopes of the element

20. Atoms
All atoms are neutral; they have the same number of electrons as protons.
Example: An atom of 42He has an atomic number of 2 and a mass of 4.
Therefore, it has 2 protons and 2 neutrons in its nucleus.
Since it has 2 positive protons (neutrons are neutral) it must have 2 negative electrons to make the total charge neutral.

22. Chemical Compounds
It is a substance formed by the chemical combination of 2 or more elements in definite proportions
Atoms in compounds are held together by chemical bonds
Examples: H2O, NaCl, C6 H12 O6

23. Chemical Compound
Pure substance formed by two or more elements chemically combined.
Ex: water: water (H2O), sodium chloride (NaCl)

24. Valence Electrons Electrons available to form bonds
Located in outer shell

25. Subscript
A subscript is a small lowered number after a symbol for an element.
H2O: the 2 is lowered and considered
a subscript.
The 2 indicates how many atoms of the element are present in that compound.

26. Chemical Formula 6 12 6 States how many atoms are in each molecule.
How many carbon atoms are in C6 H12 O6?
How many hydrogen atoms?
How many oxygen atoms? 6 12 6

27. Chemical Equations CO2 + H2O C6 H12 O6 + O2 REACTANTS PRODUCTS
Let’s say I give you a chemical equation like—
CO2 + H2O C6 H12 O6 + O2
What are the names of these compounds?
Could you tell me which side are the reactants and which side are the products?
REACTANTS
PRODUCTS
Carbon
dioxide
Water
Sugar/glucose
Oxygen
Click for answers
Click for answers

28. Ionic Bond When >/= 1 electron transfers from one atom to another
Ions: charged either + or – (depending on whether they have lost or gained an electron)
Ex: NaCl

29. Covalent Bond Electrons are shared between atoms
Single bond: share 2 electrons
Double bond: share 4
Triple bond (rare): share 6
Ex: H2O

30. Van der Waals forces
When molecules are close together an attraction can develop between oppositely charged regions of nearby molecules
Example: water molecules

31. Geckos and Van der Waals
Geckos can stick to so many surfaces in a seemingly impossible manner.
Specifically, the tiny hairs on the gecko's feet (called setae) are split at the microscopic level into as many as 1,000 branches.
As a result, even though the Van der Waals forces acting on an individual tip is small, the adhesion of a billion or so tips adds up to enough force to let the gecko stick to basically anything.

32. Water (H2O) Most abundant compound in organisms Water is polar
Unequally shares electrons between hydrogen & oxygen atoms
Makes it possible for many other compounds to other compounds to dissolve in
water

33. Water has Hydrogen Bonds
Adhesion – the attraction of unlike molecules to one another
Cohesion – the attraction of like molecules to one another
Water “beads” because of cohesion
Cohesion causes water to form drops, surface tension causes them to be nearly spherical, and adhesion keeps the drops in place.

34. Solvent-Solute Water is often called The Universal Solvent
Solvent means to dissolve, or a dissolving agent. WATER is a SOLVENT!
Solute is what is to be dissolved. Sugar and salt are solutes when they dissolve in water.

35. Mixture vs. Solution
Mixture: >/= 2 elements physically mixed but not chemically combined (M & Ms)
Solution: all components evenly distributed
Solute: substance that is dissolved
Solvent: substance in which solute dissolves
Ex: Salt water: Salt = solute, Water = solvent

36. Suspension
Mixture of water and non-dissolved material

37. Elements in the Human Body
Most abundant element in our body
Oxygen – 65%
Carbon – 18.5%
Hydrogen – 9.5%
Nitrogen – 3.3%
All of these equal 96.3%. The other 4% are trace elements: Calcium (1.5), Phosphorous (1.0), Potassium (0.4), & others.
Water
Most abundant compound in our body

38. pH Scale The pH scale measures how acidic or basic a substance is.
It ranges from 0 to 14
A pH of 7 is neutral
A pH less than 7 is acidic
A pH greater than 7 is basic

39. If #H ions > # OH ions : ACID
If # OH ions > # H ions : BASE (alkaline)
Each number on the pH scale represents an exponential change in strength
Acids: the closer to 7 (neutral) on the pH scale… the weaker the acid
Bases: the closer to 7 (neutral) on the pH scale… the weaker the base

40. Acids
Acids taste sour
Strong Acids are dangerous and can burn your skin
Examples are: Vinegar, stomach acid, and citrus fruits

41. pH Scale 14 = Basic 0 = Acidic
Oven cleaner
Bleach
Ammonia solution
Increasingly Basic
Soap
Sea water
Human blood
7 = Neutral
Neutral
Pure water
Milk
Normal
rainfall
Acid rain
Tomato juice
Increasingly Acidic
Lemon juice
Stomach acid
0 = Acidic

42. Bases Solutions containing bases are often called alkaline.
Bases taste bitter
Bases feel slippery
Strong bases are very dangerous and can burn your skin
Examples: Lye and ammonia

43. pH Question
An ecologist is testing rainwater. She tests rainwater on the south side of town and finds that the pH is Then she tests the north side of town and finds that the pH is Which is more acidic?
Click for answer
6.2 is correct!

44. Buffers
Buffers are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH.

45. Organic Compounds
Carbohydrates
Lipids
Nucleic Acids
Proteins