1. What is a chemical change vs. a physical change?

2. Atoms The basic building block of all matter Consist of: Nucleus
Proton (+)
Neutrons ( 0 )
Electrons (-)

3. INSIDE NUCLEUS PROTONS: + CHARGED NEUTRONS: NO CHARGE
ALWAYS THE SAME NUMBER OF ELECTRONS TO PROTONS

4. VALENCE SHELL - IS THE OUTERMOST SHELL

5. OUTSIDE THE NUCLEUS ELECTRONS: NEGATIVELY CHARGED
THEY ARE FOUND IN THE “ORBITAL” OR ENERGY SHELL

6. Element Made up of atoms CANNOT be broken down Examples:
Hydrogen (H), Oxygen (O), Carbon (C), Nitrogen (N)

7. Elements are found in the Periodic Table

8. Compound Made up of 2 or more different elements Chemically combined
CAN be broken down into its elements
EX: H2O

9. COMPOUND EX:
2 HYDROGEN + OXYGEN = WATER

10. Put the following in order from smallest to largest Compound, Atom, Element

11. Molecule
A group of atoms held together by covalent bonds and has no overall charge

12. How to find the number of protons, neutrons and electrons:
Atomic number tells you how many electrons or protons are in an element
How many protons or electrons are in this element?

13. how many protons or electrons are in this element?
ATOMIC NUMBER
ATOMIC MASS

14. Atomic mass = the number of protons + the number of neutrons
To find the number of neutrons, you must subtract the atomic number from the atomic mass

15. Step 1: Subtract the atomic mass from the atomic number
4 - 2 = 2
2 equals how many neutrons are in this element

16. How many protons or electrons are in N (Nitrogen) ?
How many neutrons are in Nitrogen?

17. STOP

18. BOHR MODEL

19. Bohr Model

20. Find your element on the periodic table.
Bohr Diagrams
Find your element on the periodic table.
Determine the number of electrons – it is the same as the atomic number.
This is how many electrons you will draw.

21. Find out which period (row) your element is in.
Bohr Diagrams
Find out which period (row) your element is in.
Elements in the 1st period have one energy level.
Elements in the 2nd period have two energy levels and so on

22. The second and third energy levels hold up to 8 electrons each.
In the Bohr model of the atom, the first energy level can accept up to 2 electrons.
The second and third energy levels hold up to 8 electrons each.
The fourth and fifth energy levels hold 18 electrons.

24. Electrons and energy levels
The first energy level can accept up to two electrons.
The second energy levels hold up to eight electrons.

25. Order of Filling in Dots for Electron Dot Diagrams
1 5
X 2 6
3 7

26. C Draw a nucleus with the element symbol inside.
Bohr Diagrams
Draw a nucleus with the element symbol inside.
Carbon is in the 2nd period, so it has two energy levels, or shells.
Draw the shells around the nucleus. C

27. C Bohr Diagrams Add the electrons. Carbon has 6 electrons.
The first shell can only hold 2 electrons. C

28. Bohr Diagrams
Since you have 2 electrons already drawn, you need to add 4 more.
These go in the 2nd shell.
Add one at a time -starting on the right side and going counter clock-wise. C

29. Bohr Diagrams
Try the following elements on your own: H He O Al Ne K C

30. Bohr Diagrams
Try the following elements on your own: H He O Al Ne K H

31. H Bohr Diagrams Try the following elements on your own: H – 1 electronAl Ne K H

32. He Bohr Diagrams He Try the following elements on your own: H O Al NeK He

33. He Bohr Diagrams Try the following elements on your own: H
He - 2 electrons O Al Ne K He

34. Bohr Diagrams
Try the following elements on your own: H He O Al Ne K O

35. O Bohr Diagrams Try the following elements on your own: H He
O - 8 electrons Al Ne K O

36. Al Bohr Diagrams Al Try the following elements on your own: H He O NeK Al

37. Al Bohr Diagrams Try the following elements on your own: H He O
Al - 13 electrons Ne K Al

38. Ne Bohr Diagrams Ne Try the following elements on your own: H He O AlK Ne

39. Ne Bohr Diagrams Try the following elements on your own: H He O Al
Ne - 10 electrons K Ne

40. Bohr Diagrams
Try the following elements on your own: H He O Al Ne K K

41. K Bohr Diagrams Try the following elements on your own: H He O Al Ne
K - 19 electrons K

42. Excited Atoms and Spectral Lines
Ground State-
when all of the electrons are as close to the nucleus as they can be.
Excited State-
when at least one electron has jumped to a higher energy level.

43. Valence Electrons- the electrons in the other shell
Group 1 = 1 valence electron
Group 2 = 2 valence electrons
Group 13 = 3 valence electrons
Group 14 = 4 valence electrons
Group 15 = 5 valence electrons
Group 16 = 6 valence electrons
Group 17 = 7 valence electrons
Group 18 = 8 valence electrons

44. STOP

45. Find your element on the periodic table.
Lewis Structures
Find your element on the periodic table.
Determine the number of valence electrons.
This is how many electrons you will draw.

46. C Write the element symbol.
Lewis Structures
Write the element symbol.
Carbon is in the 4th group, so it has 4 valence electrons.
Starting at the right, draw 4 electrons, or dots, clockwise around the element symbol. C

47. C On your worksheet, try these elements on your own: H P Ca Ar Cl Al
Lewis Structures
On your worksheet, try these elements on your own: H P Ca Ar Cl Al C

48. H Lewis Structures On your worksheet, try these elements on your own:P Ca Ar Cl Al H

49. P Lewis Structures On your worksheet, try these elements on your own:Ca Ar Cl Al P

50. Ca Lewis Structures On your worksheet, try these elements on your own:P Ca Ar Cl Al Ca

51. Ar Lewis Structures On your worksheet, try these elements on your own:P Ca Ar Cl Al Ar

52. Cl Lewis Structures On your worksheet, try these elements on your own:P Ca Ar Cl Al Cl

53. Al Lewis Structures On your worksheet, try these elements on your own:P Ca Ar Cl Al Al

54. Acids and Bases

55. What is pH? pH Measures how acidic or basic a substance is
Acid: has more Hydrogen ions and is represented as a on the pH scale.
Base: A substance that has LESS Hydrogen ions and more Hydroxide ions is represented as a 7.1 to 14 on the pH scale
Neutral: is a 7 on pH scale, and has an equal number of hydrogen and hydroxide ions

56. pH scale Goes from 0 through 14 Acids are below 6.9 (many foods)
Bases are above 7.1 (many household cleaners)

57. N E U T R A L
ACID
BASE
MOST BASIC
MOST ACIDIC

58. Buffers Weak acids or weak bases pH close to 7
Important to human systems

59. Important to Humans
Cells in the human body have a pH between 6.5 and 7.5.
A lower or higher pH will affect the chemical reactions that take place.
Natural buffering systems control pH, minimizing harm to cell
HOMEOSTASIS