1. The Structure of Matter (Science 10 Review)
The Atom

2. Do Now
Place your lab safety contract into the blue bin (by station 8).
Pick-up both a work booklet and a periodic table (by station 5)

3. Plan for the Week Science 10 Review
What is an element? Atom? Neutron? Proton? Electron?
Bohr and Lewis Dot Diagrams
Look at why we often need to dissolve things in water to do chemical reactions
Differences between electrolytes and non electrolytes

4. The Plan
Explain how science & technology have influenced, & been influenced by historical development & societal needs.
Science 10 chemistry review
Learn about atoms & how to diagram them
Bohr diagram
Lewis dot diagram
Practice drawing a diagram of an atom

5. Lab Safety Rap

6. Elements
A pure substance cannot be broken down into simpler substances by chemical means.
You find these on the periodic table.
The smallest part of an element is an atom.

7. Atom The basic unit of matter. It is made up of
Protons – positively charged particles located in the nucleus of an atom (p+).
Neutrons – a neutral particle located in the nucleus of an atom (no).
Electrons – a negatively charged particle located in the region surrounding the nucleus of an atom (e-).

8. Atoms
Protons
Neutrons
Electrons

9. Atoms Particle Location Charge Proton Nucleus 1+ Neutron Electron
Electron
Surrounding Nucleus
1 –

10. Joke for the Day
A neutron walks into a bar, sits down and asks for a drink. Finishing, the neutron asks "How much?"
The bartender says, "For you, no charge."

11. Atoms Atomic Number – this is the number of protons within the atoms.
Hydrogen has an atomic number of 1 which means that it has 1 proton.
Sulfur has an atomic number of 16 which means that it has 16 protons.
Carbon = _______ p+
Sodium = _______ p+
It is the number of protons which makes one element different from another.

12. Atoms
Atomic Mass - the average mass of the atoms of an element including all isotopes.
To calculate the number of neutrons, take the atomic mass and subtract the protons.
Neutrons = atomic mass – protons
Nitrogen = 14 – 7 protons = 7 neutrons
Fluorine = 19 – 9 protons = 10 neutrons
Helium = 4 -
Oxygen =16 -

13. Atoms
Mass Number – the total number of protons and neutrons in an atom.
Mass = neutrons + protons
Oxygen = 8 protons + 8 neutrons = 16
Oxygen = 8 protons + 9 neutrons = 17
These different masses are the isotopes of oxygen.

14. Practice Try #2 & 3 (p. 8) on your own.
When done-Read the bottom of page 7 from Science 20 on electrical characteristics.

15. Sketching Diagrams of Atoms
Niel Bohr developed the idea that only a certain number of electrons are able to occupy an energy level.
An energy level is a specific region surrounding the nucleus that is available for electrons.
Level 1
Level 2

16. Sketching Diagrams of Atoms
Step 1: Use the atomic number and atomic mass listed on the periodic table to determine the number of protons, electrons, and neutrons (PEN) that make up the atom.
Step 2: Draw the nucleus of the atom with the appropriate number of protons and neutrons within the nucleus.
Step 3: Use dots to represent the electrons in each energy level that surrounds the nucleus.

17. Sketching Diagrams of Atoms
Each energy level holds a specific # of e-. The number of electrons in a given energy level is shown by the number of elements in each period (row) on the periodic table.

18. Sketching Diagrams of Atoms
E.g.,. The first energy level can hold two electrons. This is shown by the first period having only two elements (H and He). The second energy level can hold eight electrons. This is shown by the second period of the periodic table having eight elements: Li, Be, B, C, N, O, F, and Ne.

19. Bohr Diagram of Chlorine Atom
Step 1: Determine the number of protons, electrons, and neutrons.
P: number of protons = atomic number
= 17
E: number of electrons = number of protons (b/c it is an atom)
N: number of neutrons = atomic mass – number of protons
= – 17
= 18 rounded

20. Bohr Diagram of Chlorine Atom
Step 2: Draw the nucleus of the atom. The nucleus of the atom contains the protons and neutrons.
17p
18n

21. Bohr Diagram of Chlorine Atom
Step 3: Draw the electrons in their appropriate energy levels.
Chlorine has 17 electrons. The first energy level can hold 2 electrons, leaving 15 more to place.
The second energy level can hold 8 electrons, leaving 7 more to place.
The third energy level can hold 8 electrons, but there are only 7 remaining. The final 7 will fit on the third energy level.

22. Bohr Diagram of Chlorine Atom

23. Bohr Diagram of Chlorine Atom
Here is a more concise way to represent the
final Bohr diagram
7e-
8e-
2e-
17p
18n

24. Practice
Try #5 a, d, & g (p. 9 of textbook)

25. Lewis Dot Diagrams
Is a representation of an atom that shows only the valence electrons.
Valence electrons are the electrons in the outermost (last) energy level.

26. Lewis Dot Diagrams

27. Lewis Dot Diagrams
Step 1: Write the chemical symbol. This symbol will represent the inner electrons and the nucleus.
Step 2: Determine the number of electrons in the outermost energy level. (The column number will help you to do this).
Step 3: Use a dot to represent each electron in the outer energy level. The dots are placed on the north, east, south, or west sides of the symbol. Each position only has room for two electrons. Double up on electrons only after all the other positions contain at least one electron.

28. Lewis Dot Diagrams
Atom
Bohr Diagram
Lewis Dot Diagram
Oxygen

29. Lewis Dot Diagrams
Atom
Bohr Diagram
Lewis Dot Diagram
Oxygen 8p 8n O

30. Lewis Dot Diagram for Oxygen

31. Lewis Dot Diagrams Atom Bohr Diagram Lewis Dot Diagram 15p 16n P
Phosphorus
15p
16n P

32. Lewis Dot Diagram

33. Practice
Try #6c & d (p. 10) on your own.

34. Octet Rule
All atoms strive to complete the outer shell with electrons and thus become a stable atom. They can complete these outer shells by gaining, losing or sharing electrons from other atoms.

35. Gaining Electrons
Chlorine has 7 electrons in the outer shell & will gain ___ electron to complete the shell.
Since it has gained ___ electron, it now has a 1- charge and is now a charged atom called an ion.
Ion – an electrically charged atom or group of atoms. A negatively charged ion is called an anion.

36. Losing Electrons
Sodium has 1 electron in its outer shell and will lose this electron to complete the outer shell.
Since it has lost an electron, it now has 1+ charge and is now a charged atom called an ion.
A positively charged ion is called a cation.

37. If an atom gains electrons, it becomes negatively charged
If an atom gains electrons, it becomes negatively charged. If it loses electrons it becomes positively charged.

38. The Periodic Table

39. Metals vs. Non-Metals
Metals tend to form positively-charged ions (cations)
Non-metals tend to form negatively-charged ions (anions)

40. Assignment
Pg. 5 & 6 of workbook.

41. Assignment
Page 8 practice # 1
Page 9 practice #5
Page 10 practice #6

42. Answers Page 8 practice # 1 - 3
Protons are found in the nucleus and have a positive charge. The # of protons is the same as the atomic number.
Neutrons are found inside the nucleus and have no charge. They add mass to the atom.
Electrons are found surrounding the nucleus and have a negative charge. They play a role in bonding.
# 2 & 3 are in the back of the textbook

43. Answers Pg. 9 # 5 4e- 2e- a) Carbon 6p+ 6no 1e- 1p+ b) Hydrogen 0no
c) Aluminium

44. Answers Pg. 9 # 5 1e- 2e- d) lithium 3p+ 4no 1e- 8e- 2e- e) sodium
f) fluorine
7e-
2e-
9p+
10no

45. Answers Pg. 9 # 5 8e- 2e- g) neon 10p+ 10no 2e- 2p+ h) helium 2no
Pg. 10 #6 is in the back of the textbook