1. UNIT 2: Basic Chemistry
BIG IDEA: Examining substances at the molecular level helps us understand basic processes of life

2. Basic Chemistry
Living and non living things are all made of the same basic building blocks of matter
Basic life processes all follow the laws of chemistry
Structure of Atoms
Chemical Reactions
Compounds and Mixtures
Water-Acids and Bases

3. Structure of Atoms
Start big and end small OrganismsOrgan Systems  Organs  Tissues Cells  Compounds Elements Atoms

4. ATOM:
Smallest amount of an element that still has the properties of that element.
Atoms have structure and are made up of smaller particles that give them their characteristics and control their interactions with other atoms

5. Structure of an Atom e N P
Nucleus: Center of atom, where protons and neutrons are located P N e

6. Structure of an Atom e
Orbit: Area outside nucleus where electrons are in constant motion N P P N e

7. Orbits spin and rotate in three dimensions.
Structure of an Atom P N e
Orbits spin and rotate in three dimensions.

8. Each Orbit is a specified distance from the nucleus.
Structure of an Atom P N e
Each Orbit is a specified distance from the nucleus.

10. Structure of an Atom P N e
Nucleus
Orbit

11. Structure of an Atom

12. An element has its own number of e, P and N
Structure of an Atom - e
An element has its own number of e, P and N N + P + P N - - e

13. The different combination of P, N and e make each element unique
Structure of an Atom - e
The different combination of P, N and e make each element unique N + P + P N - - e

14. Main Elements in Human Body
Oxygen
Carbon
Hydrogen
Nitrogen

15. Main Elements in Earth’s crust
Oxygen
Silicon
Aluminum
Iron

16. Structure of an Atom Atomic particles: - Protons, P+, Charge of +1
- Electrons, e-, charge of -1
- Neutrons, N, zero charge

17. Structure of an Atom
Normally, all the “+” of the protons and the “-” from the electrons balance out and the overall charge of an atom is zero.

18. What if an atom loses an electron?
Structure of an Atom -
What if an atom loses an electron? e e N N + P P + P P N N
- Atom becomes positive - e -

19. Structure of an Atom What if an atom gains an electron? - + + - - e NP + P N
- Atom becomes negative e - - - e

20. Any charged atom is called an ion
Structure of an Atom
Any charged atom is called an ion
- Positive ions are called cations
- Negative ions are called anions

21. Structure of an Atom-The Periodic Chart
Atomic number is the number of protons
Atomic Mass is the “approximate” number of protons + neutrons
Assume Electrons = Protons
(except Ions)

22. Atomic Mass = Protons + Neutrons
Why don’t the electrons figure in?

23. Drawing Atoms: Each orbit can hold a maximum number of electrons.
- Orbit 1: holds a max of 2
- Orbit 2: holds a max of 8
- Orbit 3: holds a max of 8
You must fill the inner orbits before adding electrons to the outer orbits.
Electrons in the outermost orbit are called valence electrons

24. Examples e e 12 Mg 24 e P N

25. Examples 8 O 16

26. Examples 10 Ne 20

27. Examples
Look at the column on periodic table to figure out Valence electrons
C __________ N____________

28. Examples
Look at the column on periodic table to figure out Valence electrons
O __________ H ____________

29. Chemical Reactions- Bonds
Compounds
Atoms are chemically bound together
Definite proportions required
Properties of a compound are different from the properties of the elements that make up that compound
Made up of many particles of the same type held together by a bond using the valence electrons

30. Types of bonds that form Compounds
Covalent- each atom shares electrons with the other
Molecules are formed by this type of bond

31. Types of bonds that form Compounds
Ionic Bond- One atom gives an electron to the other

32. IONIC:
Creates opposite charge that holds atoms together
Form crystals

33. Chemical Formulas Al2O3 2Al2O3
Subscript shows how many atoms of the element it is written after
This number (co-efficient) shows how many of the entire molecule there are

34. A + B  C synthesis reaction A  B + C decomposition
Chemical Reactions
Change in the arrangement of atoms that creates a different substance Number of atoms before and after the reaction are equal.
A + B  C synthesis reaction
A  B + C decomposition
A + B  C + D Displacement

35. Chemical Reactions A + B  C Reactants: The “stuff” you start with
Products: The “stuff” you end up with
A + B  C
Reactants
Products

36. Chemical Reactions C6H12 O6 + 6O2  6CO2 + 6H2O
C6H12 O6 + C6H12 O6  C12H22O11 + 6H2O
H20  H+ + OH-

37. Mixtures
Mixtures have “ingredients” that do not bind chemically with each other
Each ingredient keeps its own properties
Definite proportions not required
Types: solution, suspension, colloid

38. Mixtures
Solution: homogeneous; even throughout; solute (substance) completely dissolves in solvent (liquid) examples: air,
Suspension: Heterogeneous; looks even if shaken; but particles settle to bottom examples-water column in oceans and lakes

39. Mixtures
Colloid: heterogeneous BUT does not settle; sort of in between the other two.
Examples-milk and fog

40. Mixtures vs. Compounds Look at your notes:
What are three big differences between Mixtures and Compounds?

41. Properties of Water
Water is held together with special covalent bond called polar covalent bond - Means water has poles, or ends. - O is the negative end - H’s are the positive end

42. Water is the Universal Solvent
Important solvent in many solutions
Anything with a charge will attract water molecules and dissolve
Ionic and polar molecules have charge
Nonpolar molecules (like fat) do not have charge and will not dissolve

43. Properties of Water

44. Properties of Water
Cohesion: Water molecules stick together because of charges

45. Cohesion
Creates Surface tension - allows stickbugs to walk on water!

46. Adhesion Water molecules stick to other charged substances like glass
Glass stirring rod

47. Concept of pH
pH = power of Hydrogen
A way of measuring how many Hydrogen ions, H+, there are in a solution
Determines whether a solution is an acid or a base

48. Acids and Bases
Acids: a chemical that when dissolved in water releases a hydrogen ion (H+)
HX (in water)  H+ + X-

49. Properties of Acids
Taste sour – think of lemon
Turn litmus paper from blue to red
Corrodes Metal
Examples: Sulfuric Acid, Lemon Juice, Battery Acid

50. Acids and Bases
Base: a chemical that when dissolved in water releases a hydroxide ion (OH-)
XOH (in water)  OH- + X+

51. Properties of Bases
Taste bitter – cough meds.
Turn litmus paper back to blue after acid turns it red
Can cause serious burns
Examples: Bleach, KOH, NaOH

52. Acids and Bases - Examples
NaOH + H2O  Na+ + OH- + H2O
HCl + H2O  H+ + Cl- + H2O

53. Acids and Bases will “cancel” each other out
When an Acid and a Base are mixed together they will “Neutralize” each other and create Water and a Salt
This is a Neutralization Reaction

54. Neutralization Reaction
HCl + NaOH  NaCl + H2O
A Salt Water
HNO3 + KOH  KNO3 +H2O
A salt Water

55. pH Scale – a measure of the concentration of Hydrogen Ions
Acid
Neutral
(water)
Base 1 2 3 4 5 6 7 8 9 10 11 12 13 14
High H+
Low OH-
High OH-
Low H+
H+ = OH-

56. Concept of pH
Where is the “safe” pH?
pH must stay between in the human body
Another factor that must maintain homeostasis

57. Concept of pH Are there exceptions? Stomach is acidic
Intestines are basic
Buffers are necessary
weak acids or bases that react with strong acids or bases to prevent sudden changes in pH

58. What is the pH of Rain water??
Usually between Water reacts with CO2 in air to form Carbonic Acid (H2CO3)

59. What is the pH of Rain water??
Acid Rain: - Rain water reacts with pollutants such as Sulphur dioxide and Nitrogen oxides in air - Forms Sulphuric Acid, Nitric Acid, Ammonium Sulphate - Decreases pH even further