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Review of Grade
9 Chemistry

Periodic Table
Structure of the Atom
Quiz: Element Symbols
 first 20 elements plus Br and I
 transition metals: Sb, As, Bi, Cd,
Cr, Co, Cu, Au, Fe, Pb, Mn, H...
Element symbol
 Rules for writing the element symbols:
 First letter capitalize
 Second lower case

 Hints to remember...
Periodic Table
 Periods: horizontal rows
 Families or Groups: vertical columns
 Elements in the same family have simila...
Periodic Table
Metals
 left and centre of the periodic table

Transition elements
(group 3-12)

Inner Transition elements (period 6 & 7)
Properties of Metals





conduct heat and electricity
ductile and malleable
Shiny, often silvery-grey in colour
solid...
Non-Metals
 right side of the periodic table
Properties of Nonmetals
 poor conductors of heat and electricity
 usually solid or gas at room temperature
(only Bromine...
Metalloids
 Metals are separated from
non-metals by a staircase of
elements called metalloids
Properties of Metalloids
 properties intermediate between metals and
non-metals

silicon

tellurium
Chemical Families
Chemical Families
 Alkali Metals (Group 1)

 soft, silver-grey metals
 reacts easily with water

 Alkaline Earth Metal...
Chemical Families
 Halogens (Group 17)

 coloured non-metals
 very reactive

 Noble Gases (Group 18)

 colourless non...
Atom
 An atom is the smallest part of an element
that has all the element’s properties
Atomic Theory
 Each element has its own unique kind of atom
 Atoms of different elements vary in mass,
volume and reacti...
Atomic Theory
 Atoms are not the smallest particles of matter
 Subatomic particles combine together
to form atoms
 Prot...
Subatomic Particles
 Protons have a charge of 1+
 Electrons have a charge of 1 Neutrons have a charge of 0 (neutral)
 ...
Subatomic Particle Summary
Particle
Proton
Neutron
Electron

Relative
Charge
Location Influences…
Mass
Subatomic Particle Summary
Particle

Relative
Charge
Location Influences…
Mass

Proton

+

Neutron

0

Electron

-
Subatomic Particle Summary
Particle

Relative
Charge
Location Influences…
Mass

Proton

+

1

Neutron

0

1

Electron

-

...
Inside an Atom: Nucleus
 Protons and neutrons form
the core of an atom, called
the nucleus
 The protons and neutrons
are...
Atomic Number
 The number of protons in an atom is known
as its atomic number
 Each atom has a unique number of protons
...
Mass Number
 Together the protons and neutrons make up
the mass of the atom
 The mass number is the sum of the number of...
Inside an Atom: Electron
Cloud
 Surrounding the nucleus
are a series of cloud-like
energy levels called shells
or orbital...
Inside an Atom
Imagine the nucleus
to be the size of a
golf ball. Then on
this scale the first
electron shell would
be abo...
Subatomic Particle Summary
Particle

Relative
Charge
Location Influences…
Mass

Proton

+

1

Neutron

0

1

Electron

-

...
Subatomic Particle Summary
Particle

Relative
Charge
Location Influences…
Mass

Proton

+

1

Nucleus

Neutron

0

1

Nucl...
Inside an Atom: Charge
 When the number of electrons equal the
number of protons, the atom is neutral (no
charge)
 When ...
Subatomic Particle Summary
Particle

Relative
Charge
Location Influences…
Mass

Proton

+

1

Nucleus

Neutron

0

1

Nucl...
Subatomic Particle Summary
Particle

Relative
Charge
Location Influences…
Mass

Proton

+

1

Nucleus

Mass &
Charge

Neut...
Bohr Model of the atom
 electrons surround the nucleus in shells
(or orbital)
 each shell has a specific energy level
 ...
Bohr Model of the atom
 the electrons in the valence shell are called valence
electrons
Bohr diagrams
 a Bohr diagram is an
illustration of an atom that
shows the arrangement and
number of electrons in each
sh...
Let’s look at an example…
Example: Sulphur
atomic
number
sulfur
16

S
32.065
atomic mass

 Gather information
from the periodic
table to draw the
B...
Rules for drawing Bohr
diagrams
 Place the symbol of the element in the center
 Electrons are drawn as far away as possi...
Example: Sulphur
 Bohr diagram:

first shell:
2 electrons
second shell:
8 electrons

Atomic number
= 16

S

third shell:
...
What’s wrong with this
drawing?
 The placement of
electrons in the
valence shell of this
diagram is inaccurate
 Electron...
What’s wrong with this
drawing?

S

 The placement of
electrons in the
valence shell of this
diagram is inaccurate
 Prem...
Create Bohr diagrams for the
first 20 elements
2

1

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20
Lewis dot diagrams
 A drawing of an atom with ONLY it’s valence
electrons
 Example: Carbon

C

 Example: Phosphorus

P
Lewis dot diagrams
 If an atom has a full valence shell, no
electrons are needed and thus only the
element symbol is used...
Create Lewis dot diagrams for
the first 20 elements
2

1

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20
Trends in the Periodic Table

What trends do you see in the number
of valence electrons for each group?
Trends in the Periodic Table
Group 1 elements have
1 valence electron

Group 17 elements has
7 valence electron

 All ato...
Trends in the Periodic Table

What trends do you see in the number
of orbitals for each period?
Trends in the Periodic Table
Period 2 elements
have 2 orbitals

Period 3 elements
have 3 orbitals

 All atoms of elements...
Counting Atoms Terms
Terms

Definition

Affect on atom count

Subscript

Small number written to the
lower right corner af...
Counting Atoms Terms
Terms

Example

Subscript

Na3PO4

Brackets

Mg3(PO4)2

Coefficient 2 H2O
3 Mg3(PO4)2

Atom count
Counting Atoms Terms
Terms

Example

Subscript

Na3PO4

Atom count

Na = 3
P=1
O=4
Brackets
Mg3(PO4)2 Mg = 3
P=1x2=2
O=4x2...
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Review grade 9 chemistry

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Transcript of "Review grade 9 chemistry"

  1. 1. Review of Grade 9 Chemistry Periodic Table Structure of the Atom
  2. 2. Quiz: Element Symbols  first 20 elements plus Br and I  transition metals: Sb, As, Bi, Cd, Cr, Co, Cu, Au, Fe, Pb, Mn, Hg, Ni, Pt, Ag, Sn, Ti, Zn
  3. 3. Element symbol  Rules for writing the element symbols:  First letter capitalize  Second lower case  Hints to remembering symbols for elements:  Hint 1: applies to hydrogen, boron, carbon, nitrogen, oxygen, fluorine, phosphorus, sulfur, iodine etc.  Hint 2: applies to helium, lithium, beryllium, neon, aluminum, silicon, argon, calcium, bromine etc.  Hint 3: applies to magnesium, chlorine, chromium, manganese, zinc, cadmium, platinum etc.  Hint 4: applies to sodium, potassium, iron, copper, silver, tin, antimony, gold, mercury etc.
  4. 4. Periodic Table  Periods: horizontal rows  Families or Groups: vertical columns  Elements in the same family have similar physical and chemical properties
  5. 5. Periodic Table
  6. 6. Metals  left and centre of the periodic table Transition elements (group 3-12) Inner Transition elements (period 6 & 7)
  7. 7. Properties of Metals     conduct heat and electricity ductile and malleable Shiny, often silvery-grey in colour solid at room temperature (except mercury)
  8. 8. Non-Metals  right side of the periodic table
  9. 9. Properties of Nonmetals  poor conductors of heat and electricity  usually solid or gas at room temperature (only Bromine is a liquid at room temperature)  brittle  dull
  10. 10. Metalloids  Metals are separated from non-metals by a staircase of elements called metalloids
  11. 11. Properties of Metalloids  properties intermediate between metals and non-metals silicon tellurium
  12. 12. Chemical Families
  13. 13. Chemical Families  Alkali Metals (Group 1)  soft, silver-grey metals  reacts easily with water  Alkaline Earth Metals (Group 2)  silver-grey metals  harder and less reactive than group 1 metals
  14. 14. Chemical Families  Halogens (Group 17)  coloured non-metals  very reactive  Noble Gases (Group 18)  colourless non-metals  odourless  very unreactive (does not combine easily with other atoms)
  15. 15. Atom  An atom is the smallest part of an element that has all the element’s properties
  16. 16. Atomic Theory  Each element has its own unique kind of atom  Atoms of different elements vary in mass, volume and reactivity
  17. 17. Atomic Theory  Atoms are not the smallest particles of matter  Subatomic particles combine together to form atoms  Protons  Neutrons  Electrons
  18. 18. Subatomic Particles  Protons have a charge of 1+  Electrons have a charge of 1 Neutrons have a charge of 0 (neutral)  The masses of protons and neutrons are almost 2000 times greater than the mass of electrons
  19. 19. Subatomic Particle Summary Particle Proton Neutron Electron Relative Charge Location Influences… Mass
  20. 20. Subatomic Particle Summary Particle Relative Charge Location Influences… Mass Proton + Neutron 0 Electron -
  21. 21. Subatomic Particle Summary Particle Relative Charge Location Influences… Mass Proton + 1 Neutron 0 1 Electron - 1/2000
  22. 22. Inside an Atom: Nucleus  Protons and neutrons form the core of an atom, called the nucleus  The protons and neutrons are held together by strong forces
  23. 23. Atomic Number  The number of protons in an atom is known as its atomic number  Each atom has a unique number of protons and thus each atom has a different atomic number
  24. 24. Mass Number  Together the protons and neutrons make up the mass of the atom  The mass number is the sum of the number of protons and neutrons in an atom
  25. 25. Inside an Atom: Electron Cloud  Surrounding the nucleus are a series of cloud-like energy levels called shells or orbitals  These shells are occupied by electrons  The electron cloud is 10,000 times larger than the nucleus
  26. 26. Inside an Atom Imagine the nucleus to be the size of a golf ball. Then on this scale the first electron shell would be about one kilometer from the golf ball, the second shell about four kilometers, the third nine kilometers etc.
  27. 27. Subatomic Particle Summary Particle Relative Charge Location Influences… Mass Proton + 1 Neutron 0 1 Electron - 1/2000
  28. 28. Subatomic Particle Summary Particle Relative Charge Location Influences… Mass Proton + 1 Nucleus Neutron 0 1 Nucleus Electron - 1/2000 Shell
  29. 29. Inside an Atom: Charge  When the number of electrons equal the number of protons, the atom is neutral (no charge)  When there are more electrons (-) than protons (+) the charge is negative  When there are less electrons (-) than protons (+) the charge is positive
  30. 30. Subatomic Particle Summary Particle Relative Charge Location Influences… Mass Proton + 1 Nucleus Neutron 0 1 Nucleus Electron - 1/2000 Shell
  31. 31. Subatomic Particle Summary Particle Relative Charge Location Influences… Mass Proton + 1 Nucleus Mass & Charge Neutron 0 1 Nucleus Mass Electron - 1/2000 Shell Charge
  32. 32. Bohr Model of the atom  electrons surround the nucleus in shells (or orbital)  each shell has a specific energy level  the innermost shell holds 2 electrons  the next two shells hold 8 electrons  the outermost shell is called the valence shell
  33. 33. Bohr Model of the atom  the electrons in the valence shell are called valence electrons
  34. 34. Bohr diagrams  a Bohr diagram is an illustration of an atom that shows the arrangement and number of electrons in each shell N 7p 7n S Cl 16p 16n 17p 18n
  35. 35. Let’s look at an example…
  36. 36. Example: Sulphur atomic number sulfur 16 S 32.065 atomic mass  Gather information from the periodic table to draw the Bohr diagram Atomic number = number of protons = number of electrons (in a NEUTRAL atom) = 16
  37. 37. Rules for drawing Bohr diagrams  Place the symbol of the element in the center  Electrons are drawn as far away as possible (e.g. north-south, east-west orientations)  Electrons pair up if there are more than 4  Keep count of the maximum number of electrons per shell (first shell holds 2 electrons, the next two shells hold 8 each)
  38. 38. Example: Sulphur  Bohr diagram: first shell: 2 electrons second shell: 8 electrons Atomic number = 16 S third shell: 6 electrons total: 16 electrons In a sulphur atom, the valence shell has 6 electrons
  39. 39. What’s wrong with this drawing?  The placement of electrons in the valence shell of this diagram is inaccurate  Electrons need to be as far away as possible.
  40. 40. What’s wrong with this drawing? S  The placement of electrons in the valence shell of this diagram is inaccurate  Premature pairing of electrons
  41. 41. Create Bohr diagrams for the first 20 elements 2 1 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
  42. 42. Lewis dot diagrams  A drawing of an atom with ONLY it’s valence electrons  Example: Carbon C  Example: Phosphorus P
  43. 43. Lewis dot diagrams  If an atom has a full valence shell, no electrons are needed and thus only the element symbol is used  Example: Helium = He
  44. 44. Create Lewis dot diagrams for the first 20 elements 2 1 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
  45. 45. Trends in the Periodic Table What trends do you see in the number of valence electrons for each group?
  46. 46. Trends in the Periodic Table Group 1 elements have 1 valence electron Group 17 elements has 7 valence electron  All atoms of elements in the same group have the same number of valence electrons  As the group number increases, so do the number of valence electron
  47. 47. Trends in the Periodic Table What trends do you see in the number of orbitals for each period?
  48. 48. Trends in the Periodic Table Period 2 elements have 2 orbitals Period 3 elements have 3 orbitals  All atoms of elements in the same period have the same number of shells (orbitals)  As the period number increases, so do the number of shells
  49. 49. Counting Atoms Terms Terms Definition Affect on atom count Subscript Small number written to the lower right corner after the element symbol. Indicates number of atoms of that element. If there are no numbers, a ‘1’ is assumed. Brackets Surrounds a group of atoms. Used when there is more than one of a group of atoms (e.g. polyatomics) Large number written in front of a molecule. All elements inside a bracket is in multiplies of the subscript written after the bracket. Coefficient Indicates the total number of the molecule. All elements after it would be in multiples of the number.
  50. 50. Counting Atoms Terms Terms Example Subscript Na3PO4 Brackets Mg3(PO4)2 Coefficient 2 H2O 3 Mg3(PO4)2 Atom count
  51. 51. Counting Atoms Terms Terms Example Subscript Na3PO4 Atom count Na = 3 P=1 O=4 Brackets Mg3(PO4)2 Mg = 3 P=1x2=2 O=4x2=8 Coefficient 2 H2O H=2x2=4 O=1x2=2 3 Mg3(PO4)2 Mg = 3 x 3 = 9 P=1x2x3=6 O=4x2x3= 24
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