Download Name

Name __________________________________________Date_______________________Hr_____
HOMEWORK PACKET – CHANGES & BALANCING
PART I – PHYSICAL AND CHEMICAL CHANGES
Identify each of the following as a Physical or Chemical Change.
Put a P next to Physical Changes Put a C next to Chemical Changes
1. A piece of wood burns to form ash. _________
9. A tire is inflated with air. _________
2. Water evaporates into steam. _________
10. A plant turns sunlight, CO2, and water into
3. A piece of cork is cut in half. _________
sugar and oxygen. _________
4. A bicycle chain rusts. _________
11. Sugar dissolves in water. _________
5. Food is digested in the stomach. _________
12. Eggs turn into an omelet. _________
6. Water is absorbed by a paper towel. _________
13. Milk sours. _________
7. Hydrochloric Acid reacts with zinc. _________
14. A popsicle melts. _________
8. A piece of an apple rots on the ground._________
15. Turning brownie mix into brownies. _________
Choose 2 of the above examples and explain why you chose chemical or physical. Please choose one of each
type of change. Back up your explanation.
Physical change explanation:
_______________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Chemical change explanation: _______________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
PART II – DEALING WITH CHEMICAL EQUATIONS
Fill in the blank with the appropriate term(s).
chemical change
coefficient
balanced equation
chemical reaction
subscript
physical property
physical change
1. The “3” in CaCO3 ________________________________________
2. The state, size, or shape of a substance ________________________________________
3. The “6” in 6H2O________________________________________
4. What happens when two substances react to produce entirely different
substances________________________________________
5. An equation with an equal number of atoms in the reactants and
products________________________________________
6. Ice melting is an example of this kind of change ________________________________________
7. You cannot create or lose mass in a ________________________________________
1
Counting Atoms
The formula for a compound indicates the elements that make up the compound and the
number of atoms of each element present in the compound. These numbers of atoms are
indicated by the use of small numbers called subscripts. Sometimes groups of atoms act as a single
atom. Such a group of atoms is called a polyatomic ion. If a polyatomic ion is used in a formula
more than once, it is put in parentheses and the subscript appears outside of the parentheses. When
a
subscript appears outside the parentheses, it indicates that all of the elements inside the parentheses
should
be multiplied by that subscript. For example, the formula Fe(OH) 3 indicates the combination of one atom of iron, Fe,
three atoms of oxygen, O, and three atoms of hydrogen, H.
In the following examples, list each element in the compound and the number of atoms of each element present.
The first example has been done for you. You may already be familiar with some of the compounds.
Name
Use
Formula
Calcium carbonate
Limestone
CaCO3
Aspirin
Pain reliever
C9H8O4
Magnesium hydroxide
Found in milk of magnesia
Paradichlorobenzene
Moth crystals
C6H4Cl2
Acetic acid
Found in vinegar
C2H4O2
Trinitrotoluene (TNT)
Explosive
Calcium dihydrogen
phosphate
Fertilizer
Pyrite
Fool’s gold
Sucrose
Sugar
C12H22O11
Name
Use
Formula
Sulfuric acid
Used in car batteries
Atoms in Formula
Ca = calcium =1
C = carbon = 1
O = oxygen =3
Mg(OH)2
C7H5(NO2)3
Ca(H2PO4)2
FeS2
Atoms in Formula
H2SO4
2
Cellulose
Found in wood products such
as your pencil and paper
C6H7O2(OH)3
Asbestos
Insulator
Dichlorodiphenyltrichloroethane
(DDT)
Banned pesticide
Silicon dioxide
Sand
SiO2
Iron oxide
Rust
Fe2O3
Butane
Lighter fluid
C4H10
H4Mg3Si2O9
C14H9Cl5
PART III – BALANCING EQUATIONS
(1) Circle each subscript in each chemical formula.
(2) Draw a square around each coefficient.
(3) Answer the questions related to each chemical formula.
How many atoms each element are in the
formula shown?
2
C = ______ H = ______
What element does the O represent?
___________________
1.
O
5. 2Na2SO4
2. CO2
How many atoms of each element are in the
formula shown?
C = ______ O = ______
3. 5H2
How many atoms of Hydrogen are in this
formula as shown?
______
4. 2C2H6
How many atoms each element are in the
formula shown?
Na = ______ S = ______ O = ______
6. H2
What element does the H represent?
___________________
7. SO4
How many atoms of each element are in the
formula shown?
S = ______ O = ______
3
8. 5C2
How many atoms of carbon are in this formula
as shown?
______
9. 2Fe(OH)3
How many atoms each element are in the
formula shown?
Fe = ______ O = ______ H= ______
How many atoms of each element are in the
formula shown?
Al = ______ O = ______ H = ______
10. Al(OH)2
Part B: Label the chemical equation using PRODUCT, REACTANT, SUBSCRIPT, COEFFICIENT, and
YIELDS.
2 Mg + O2

2 MgO
Part C: Balance each of the following equations. Remember to count your atoms!
1.
H2
2.
H2O2
3.
Na
+
O2

H2O

H2O
+
O2
+
O2

Na2O
4.
N2
+
H2

NH3
5.
P4
+
O2

P4O6
6.
C
+
H2

CH4
7.
Al2 O3

Al +
O2
8.
Fe
+ H2O 
Fe3O4
+
NO
MORE!
H2
4
9. C2 H6
+
10. Na2SO4
O2 
+
CaCl2
CO2

+
CaSO4
H2O
+
NaCl
Atoms are not _______________ or _____________ during a chemical reaction. We know this because
of the Law of ____________________________. Scientists know that there must be the ___________
number of atoms on each ___________ of the ____________. To balance the chemical equation, you
must add _______________ in front of the chemical formulas in the equation. You cannot _______ or
___________ subscripts!
Part A: Identify the following parts of each chemical formula by circling the subscripts and drawing a
square around the coefficients.
H2
2 HCl
4 O2
CH4
3 CO3
2 NaOH
Part B: List the symbols for the atoms in each formula and give the number of each.
C2H6
NH3
2MgO
3 Al(OH)3
4P4O10
2 H2O2
Steps:
1) Determine number of atoms for each element.
2) Pick an element that is not equal on both sides of the equation.
3) Add a coefficient in front of the formula with that element and adjust your counts.
4) Continue adding coefficients to get the same number of atoms of each element on each side.
For Example:
Mg +
O2
Mg =

MgO
O=
Mg =
Try these:
1. Ca
+
O2

2. N2
+
H2

Ca =
N=
3. Cu2O
Cu =
4. H2O2
O=
O=
H=
Ca =
N=
+
C


H2O
+
O=
C=
CaO
NH3
Cu
Cu =
O=
H=
+
CO2
O=
C=
O2
5
H=
O=
H=
O=
More Balancing Act Practice
Continue to balance each equation. Remember you cannot add subscripts or place coefficients in the
middle of a chemical formula!!!!
1.
Na
+
MgF2 
2.
Mg
+
HCl
3.
Cl2
+
4.
NaCl
5.
NaF
+
Mg

MgCl2 +
H2
KI

KCl
+
I2

Na
+
Cl2
Na
+
O2

Na2O
6.
Na
+
HCl

H2
+
NaCl
7.
K
+
Cl2

KCl
Challenge: This one is tough!
C2H6 +
O2

CO2
+
H2O
PART IV - BONDING
Directions: Classify the following compounds as ionic (metal + non metal), covalent (nonmetal +
nonmetal), or both (compound containing both ionic and covalent bonds).
1. CaCl2
____________________
6. NaF
____________________
2. CO2
____________________
7. Na2CO3
____________________
3. H2O
____________________
8. CH4
____________________
4. BaSO4
____________________
9. SO3
____________________
5. K2O
____________________
10. LiBr
____________________
6
11. MgO
____________________
16. NO2
____________________
12. NH4Cl
____________________
17. AlPO4
____________________
13. HCl
____________________
18. FeCl3
____________________
14. KI
____________________
19. P2O5
____________________
15. NaOH
____________________
20. N2O3
____________________
Elements and Bonding
1)
Classify each of the following elements as an alkali metal, an alkaline-earth metal, transition metal,
metalloid, halogen, or noble gas based on its position in the periodic table:


2)
3)
boron
____________________
gold
____________________

krypton
____________________

calcium
____________________
How many valence electrons do each of the following elements have?

carbon ______

xenon ______

selenium ______

potassium ______

Which of the following ions are likely to be formed?
 N+5 ______
 F-1 ______

P-3 ______


Mg+2 ______
He+ ______

Al+2 ______
4)
Explain why oxygen is a fairly reactive element while neon is not.
5)
Explain why beryllium loses electrons when forming ionic bonds, while sulfur gains electrons.
6)
Explain why fluorine and chlorine have similar reactivity’s (the word “valence” should be somewhere in
your answer!)
7)
What ions will the following form?
7

Oxygen___________

Sodium___________

Lithium___________

Sulfur___________
Bonding Basics - Ionic Bonds
Complete the chart for each element.
Element
# of Protons
# of Electrons # of Valence Electrons
Oxidation Number
Sodium
Chlorine
Beryllium
Fluorine
Lithium
Oxygen
Phosphorus
Follow these steps to complete each ionic bond.
a) Write the symbols for each element.
b) Use colored pencils to create the Lewis structure for each (each element & its electrons must be different
color).
c) Draw an arrow (or more if needed) to show the transfer of electrons and move the electron to the new
location.
d) Determine the charge for each ion and write the formula.
e) Make sure the sum of the oxidation numbers is zero and write the chemical formula.
(1) Potassium + Fluorine
(2) Magnesium + Iodine
(3) Sodium + Oxygen
8
(4) Sodium + Chlorine
(5) Calcium + Chlorine
(6) Aluminum + Chlorine
Bonding Basics - Covalent Bonds
Complete the chart for each element.
Element
# of Protons
# of Electrons
# of Valence Electrons
# of Electrons to Fill
Outer Shell
Carbon
Chlorine
Hydrogen
Phosphorus
Oxygen
Sulfur
Nitrogen
Follow your teacher’s directions to complete each covalent bond.
a) Write the symbols for each element.
b) Use colored pencils (different color for each element & its electrons) to create the Lewis structure for
each.
c) Rearrange the electrons to pair up electrons from each atom.
d) Draw circles to show the sharing of electrons.
e) Draw the bond structure using symbols and lines.
f) Write the chemical formula for each molecule.
(1) Hydrogen + Hydrogen
9
(2) Hydrogen + Oxygen
(3) Chlorine + Chlorine
(4) Oxygen + Oxygen
(5) Carbon + Oxygen
(6) Carbon + Hydrogen
PART IV: WRITING AND NAMING FORMULAS
Writing Formulas
Write the correct formula for all of the following:
1) magnesium oxide
7) sodium sulfide
13) strontium phosphide
2) lithium bromide
8) radium bromide
14) barium iodide
3) calcium nitride
9) magnesium sulfide
15) sodium fluoride
4) aluminum sulfide
10) aluminum nitride
16) calcium bromide
5) potassium iodide
11) cesium sulfide
17) beryllium oxide
6) strontium chloride
12) potassium chloride
18) strontium sulfide
10
11