Transcript Elements, Compounds, and Chemical Equations

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Elements, Compounds, and
Chemical Equations
Counting Atoms and Balancing
Equations
1. Counting Subatomic Particles:
Use the periodic table
• The atomic number is the same as the number
of protons.
• The number of protons is the same as the
number of electrons.
• The mass number is the protons added to the
neutrons.
Atomic Number = Protons = Electrons (APE)
Mass Number = Protons + Neutrons
Neutrons = Mass Number - Protons
1. Counting Subatomic Particles:
Find the number of protons, neutrons, and
electrons in:
Lithium
Atomic Number = Protons = Electrons (APE)
Mass Number = Protons + Neutrons
Neutrons = Mass Number - Protons
1. Counting Subatomic Particles:
Find the number of protons, neutrons, and
electrons in:
Lithium
Atomic Number = 3
Protons = 3
Neutrons = 4
Electrons = 3
Mass Number = 7
1. Counting Subatomic Particles:
Find the number of protons, neutrons, and
electrons in:
Gold
Atomic Number = Protons = Electrons (APE)
Mass Number = Protons + Neutrons
Neutrons = Mass Number - Protons
1. Counting Subatomic Particles:
Find the number of protons, neutrons, and
electrons in:
Argon
1. Counting Subatomic Particles:
Find the number of protons, neutrons, and
electrons in:
Lead
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
• Subscripts describe the number of that type of
atom. They appear after the element symbol,
are small, and written hanging below the
symbol.
• Coefficients describe the number of molecules
present. Coefficients apply to all elements in
the molecule. They are written before the
formula for the molecule and are large.
4H2O
Coefficient:
There are 4
molecules of
water.
Subscript:
There are 2 atoms
of Hydrogen in each
water molecule.
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
• Subscripts describe the number of that type of
atom. They appear after the element symbol,
are small, and written hanging below the
symbol.
• Coefficients describe the number of molecules
present. Coefficients apply to all elements in
the molecule. They are written before the
formula for the molecule and are large.
• H2O = 2 hydrogen and 1 Oxygen
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
• Subscripts describe the number of that type of
atom. They appear after the element symbol,
are small, and written hanging below the
symbol.
• Coefficients describe the number of molecules
present. Coefficients apply to all elements in
the molecule. They are written before the
formula for the molecule and are large.
• 3H2O = 6 Hydrogen and 3 Oxygen
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
Count and Draw the atoms in
the molecule.
NH4
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
Count and Draw the atoms in
the molecule.
NH4
N = Nitrogen = 1
H = Hydrogen = 4
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
Count and Draw the atoms in
the molecule.
2NH4
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
Count and Draw the atoms in
the molecule.
NH4
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
Count the atoms present:
C6H12O6
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
C6H12O6
Carbon – C – 6
Hydrogen – H – 12
Oxygen – O – 6
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
3C6H12O6
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
3C6H12O6
Carbon – C – 6 x 3 = 18
Hydrogen – H – 12 x 3 = 36
Oxygen – O – 6 x 3 = 18
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
2NaC2H3O2
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
2NaC2H3O2
Sodium - Na – 1 x 2 = 2
Carbon – C – 2 x 2 = 4
Hydrogen – H – 3 x 2 = 6
Oxygen – O – 2 x 2 = 4
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
KNO3
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
4KNO3
3. Balancing Equations:
Count the atoms in the reactants and the products.
• Count the total number of each type of atom on the
reactant (ingredient) side.
• Count the total number of each type of atom in the
product (what you make) side
• If the number of each type of atom matches, the
equation is balanced. If the numbers do not match
the equation is not balanced.
• Equations must be balanced to show that the same
atoms that go into a reaction are the atoms that
come out, THEY ARE JUST REARRANGED to make
new substances.
3. Balancing Equations:
Count the atoms in the reactants and the products.
2Cu + O2  2CuO
Reactants
Element
Copper
Oxygen
Products
3. Balancing Equations:
Count the atoms in the reactants and the products.
2Cu + O2  2CuO
Reactants
Element
Products
2
Copper
2
2
Oxygen
2
The Equation is Balanced!!!
3. Balancing Equations:
Count the atoms in the reactants and the products.
2H2O  3H2 + O2
Reactants
Element
Hydrogen
Oxygen
Products
3. Balancing Equations:
Count the atoms in the reactants and the products.
2H2O  3H2 + O2
Reactants
Element
Products
4
Hydrogen
6
2
Oxygen
2
3. Balancing Equations:
Count the atoms in the reactants and the products.
3Fe + 4H2O  4H2 + Fe3O4
Reactants
Element
Iron
Hydrogen
Oxygen
Products
3. Balancing Equations:
Count the atoms in the reactants and the products.
3Fe + 4H2O  4H2 + Fe3O4
Reactants
Element
Products
3
Iron
3
8
Hydrogen
8
4
Oxygen
4
3. Balancing Equations:
Count the atoms in the reactants and the products.
2Fe2O3 + 3H2  2Fe + 3H2O
Reactants
Element
Iron
Oxygen
Hydrogen
Products
3. Balancing Equations:
Count the atoms in the reactants and the products.
CaCO3  CaO + CO2
Reactants
Element
Calcium
Carbon
Oxygen
Products
3. Balancing Equations:
Count the atoms in the reactants and the products.
CaCO3  CaO + CO2
Reactants
Element
Products
1
Calcium
1
1
Carbon
1
3
Oxygen
3
3. Balancing Equations:
Count the atoms in the reactants and the products.
2NaCl  2Na + Cl2
Reactants
Element
Products
3. Balancing Equations:
Count the atoms in the reactants and the products.
2NaCl  2Na + Cl2
Reactants
Element
Products
2
Na
2
2
Cl
2
3. Balancing Equations:
Count the atoms in the reactants and the products.
CH4 + 2O2  CO2 + 2H2O
3. Balancing Equations:
Count the atoms in the reactants and the products.
CH4 + 2O2  CO2 + 2H2O
Reactants
Element
Products
1
C
1
4
H
4
4
O
4
3. Balancing Equations:
Count the atoms in the reactants and the products.
C5H12 + 6O2  5CO2 + 6H2O
3. Balancing Equations:
Count the atoms in the reactants and the products.
C5H12 + 6O2  5CO2 + 6H2O
Reactants
Element
Products
5
C
5
12
H
17
12
O
16
2. Counting Atoms in Chemical Formulas:
Examine the subscripts and coefficients
C6H12O6