Download Chemical Practice

Name _Answers___________________________
Date ____________________ Hour _________
Chemical Practice
Examples:
Oxidation numbers need to be balanced / canceled out!
1. If an element has +3 oxidation #, it has _3_ valence electrons and wants to (lose/gain) _3_ electrons.
+2 oxidation means there is _2_ valence electrons and wants to (lose/gain) _2_ electrons.
- 2 oxidation means there is _6_ valence electrons and wants to (lose/gain) _2_ electrons.
- 1 oxidation means there is _7_ valence electrons and wants to (lose/gain) _1_ electrons.
+1 oxidation means there is _1_ valence electrons and wants to (lose/gain) _1_ electrons.
The noble gasses have _full_ valence electrons and want to (lose/gain) _0_ electrons.
2. What is ionic bonding?
Ionic bonding describes the process where electrons are transferred between elements creating
oppositely charged ions that then are attracted to each other.
3. What is the definition of an oxidation number?
Oxidation numbers are the charges of an ion. So, an oxidation number includes both a charge (positive
or negative) and a number.
4. If an element has an oxidation number of +2, what will it want to do?
Those elements will want to lose 2 electrons.
5. Hydrogen cannot combine with Neon to form a compound. Why?
Neon is a noble gas, meaning that it already has a full valence. As a result, neon is already stable and
does not want to gain or lose electrons.
6. Calcium and Potassium cannot combine to form a compound. Why?
Calcium has an oxidation number of +2, meaning it would like to lose 2 electrons. And, potassium has
an oxidation number of +1, meaning it would like to lose 1 electron. Transferring electrons is not
possible and like charges repel.
7. In order for an ionic bond to happen, a _+_ ion must mix with a _-_ ion.
8. If an element loses three electrons, what is its new charge?
That element would have a charge of +3.
9. How can you explain why the elements in Carbon’s family have either +4 or – 4 oxidation number?
It is equally easy for elements with 4 valence electrons to lose or gain 4 electrons so depending on what
happens, they can have either a positive or negative charge.
10. To balance out the oxidation #’s for a +1 and -2 bond, there needs to be 2 (+1) for every 1 (-2).
To balance out the oxidation #’s for a +3 and -3 bond, there needs to be _1_ (+3) for every _1_ (-3).
To balance out the oxidation #’s for a +2 and -1 bond, there needs to be _1_ (+2) for every _2_ (-1).
To balance out the oxidation #’s for a +1 and -4 bond, there needs to be _4_ (+1) for every _1_ (-4).
To balance out the oxidation #’s for a +2 and -3 bond, there needs to be _3_ (+2) for every _2_ (-3).
To balance out the oxidation #’s for a +3 and -2 bond, there needs to be _2_ (+3) for every _3_ (-2).
11. What will happen if you mix some of an element that wants to gain three electrons with some that wants
to lose one electron? [Hint: consider the ions each would form.]
An element that wants to gain 3 electrons would acquire a charge of -3. An element that wants to lose 1
electron would acquire a charge of +1. These elements would form an ionic bond. Each molecule of the
compound would have one -3 ion and three +1 ions.
12. What will happen if you mix together a bunch of two different elements, one with an oxidation of +2
and one with the oxidation of – 1? [Hint: the oxidation numbers need to cancel out.]
An ion with an oxidation of +2 would form an ionic bond with an ion with oxidation of -1. Each
molecule of that compound would have one +2 ion and two -1 ions.
13. What will happen if you mix +2 ions with – 3 ions? [Hint: the oxidations need to cancel out.]
Again, an ionic bond would form. The molecule of the compound form would contain three +2 ions and
two -3 ions.
2
14. Write in the Oxidation numbers of the elements on the left column and the top row on the table below.
Then, write the formula of the combination of ions on the left column and the top row. Study the ones
done for you.
P _-3_
S _-2_
F _-1_
Li _+1_
Li3P
Li2S
LiF
Be _+2_
Be3P2
BeS
BeF2
Al _+3_
AlP
Al2S3
AlF3
Cu +1
Cu3P
Cu2S
CuF
Cu +2
Cu3P2
CuS
CuF2
Fe +2
Fe3P2
FeS
FeF2
Fe +3
FeP
Fe2S3
FeF3
15. The metals in families 3 – 12 behave differently than the other families in terms of forming ions.
Copper (Cu) and Iron (Fe) are examples of these metals. The oxidation number of these metals will be
given to you. What is one simple observation you can make about one of these metal ions?
Some of these metals have more than one oxidation number.
16. Take a guess…..why you think some metal ions might have two oxidation numbers?
Answers may vary … It’s possible that these metals can have different electron arrangements and so
have different valences.
17. What is a polyatomic ion?
A polyatomic ion is an ion (charged particle) made of more than one atom. {Your polyatomic ions can
be found on the back of your periodic table.}
Formulas and Naming Compounds
READ: Write the oxidation number for each ion (some are given). Write the formula for the ionic bond and
the name of this new compound. Always write the cation (+ ion) first in the formula.
Use the back of your periodic table to put the names of the two ions together. The names of the ions may be a
little different to show that it is now in a compound. The chlorine ion is called chloride, bromine is bromide,
sulfur is sulfide, oxygen is oxide….. If they will not combine, write NOT POSSIBLE.
Ion with oxidation
number
Ion with oxidation
number
Compound formula
Name of compound
Mg +2
Br –1
MgBr2
Magnesium bromide
H _+1_
Cl _-1_
HCl
Hydrogen chloride
Ca _+2_
Br _-1_
CaBr2
Calcium bromide
3
Ion with oxidation
number
Ion with oxidation
number
Compound formula
Name of compound
H _+1_
S _-2_
H2S
Hydrogen sulfide
Na _+1_
Ar _0_
Will not bond
Not possible
Ca _+2_
Na _+1_
Will not bond
Not possible
Fe +2
O _-2_
FeO
Iron (II) oxide
Fe +3
O _-2_
Fe2O3
Iron (III) oxide
Cl _-1_
Be _+2_
BeCl2
Beryllium chloride
Si _+4_
O _-2_
SiO2
Silicon oxide
H _+1_
P _-3_
H3P
Hydrogen phosphide
Xe _0_
Mg _+2_
Will not bond
Not possible
P _-3_
Al _+3_
AlP
Aluminum phosphide
Cu +2
Cl _-1_
CuCl2
Copper (II) chloride
Cu +1
Cl _-1_
CuCl
Copper (I) chloride
He _0_
F _-1_
Will not bond
Not possible
Br _-1_
Al _+3_
AlBr3
Aluminum bromide
NH4 _+1_
PO4 _-3_
(NH4)3PO4
Ammonium phosphate
NH4 _+1_
NO3 _-1_
NH4NO3
Ammonium nitrate
SiO4 –4
K _+1_
K4SiO4
Potassium silicate
B _+3_
OH _-1_
B(OH)3
Boron hydroxide
Using the back of your periodic table, find the formulas for the following compounds containing polyatomic
ions. First write the formula for each ion which is being bonded.
Compound Name
Ions in Compound
Compound Formula
Sodium Carbonate:
Na +1
___Na2CO3
+2
CO3 –2
-2
___
Magnesium Sulfate:
Mg _____SO4 _______
___MgSO4____________
Potassium Nitrate:
K+1_______NO3-1______
___KNO3_____________
+3
-1
Aluminum Hydroxide:
Al ______OH _______
___Al(OH)3___________
Ammonium Carbonate:
NH4+1_____CO3-2______
___(NH4)2CO3_________
Iron (III) Oxide:
Fe+3______O-2________
___Fe2O3_____________
Sulfur Phosphate:
S-2________PO4-3_____
___Not possible________
Calcium Chlorite:
Ca+2_______ClO2-1_____
___Ca(ClO2)2__________
Hydrogen Hydroxide:
+1
-1
H ________OH ______
4
___HOH______________ (H2O)