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Chemical Bonds Worksheet
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Ionic Bonding
How create the Lewis Structure (Dot Diagram) of an
atom. (Problems 1-8)
Example: Draw the Lewis Structure of a Magnesium Atom.
1.
Find the atomic number of that element by locating that element using the
periodic table. The atomic number tells us the number of total protons,
electrons, and neutrons in the atom.
Mg has an atomic number of 12.
Mg has 12 TOTAL electrons
2.
Find the number of valence electrons. Remember that atomic numbers tell
us the number of electrons, but NOT the number of VALENCE electrons.
Valence electrons are the electrons in the outermost energy level, that
determine if the element forms a chemical bond or not.
There can be 2 electrons in the innermost energy level of the atom
There can be 8 electrons in each of the energy levels after the 1st one.
Magnesium
Atomic
Number
Atomic
Mass
Number of
Protons,
electrons,
and
neutrons
Column in
the periodic
table
Number of
valence
electrons
12
24.305
amus
12
2
2
Mg has 2 valence electrons because it has 12 total electrons. 2 of those occupy the 1 st energy
level, and 8 of them occupy the 2nd energy level. Therefore there are 2 electrons left over in the 3 rd
energy level.
Shortcut- Mg has 2 valence electrons because it is in the 2nd column.
3.
Draw the Lewis structure, by writing down the atomic symbol. Then place each valence electron
around the symbol as a dot. Place one at each of the 4 sides of the symbol, then double them up.
The most valence electrons that an element can have would be 8 and the least would be 1 valence
electron.
BAD
GOOD
Lewis Structures of Atoms: Draw Lewis Structures for the following elements.
1. Cl
5. S
2. H
6. Ca
3. O
4. Ar
7. F
8. Na
How to Convert an atom into an ION. (Problems 9-16)
Example: What does a Chlorine Ion look like?
1.
2.
Draw the lewis structure of a chlorine atom.
Follow the octet rule. Atoms are unstable until they have a full
outer shell of electrons. For H and He, this means that they have 2
electrons. For all other elements, this means that they have 8.
For this reason, Noble Gases do NOT form ions.
If chlorine gains just 1 electron, it will have 8 electrons in its outer
shell. So add 1 electron to the chlorine atom.
Atom
Ion
F
-
Ca
2+
S
2-
Ne
Does not
form an
ion
3.
Remember that the charge of an electron is negative. So if we gain 1 electron our atom gets a
negative charge. All negatively charged ions are called anions. Write the ion’s charge in the
upper right hand side of the lewis structure.
4.
If an ion loses electrons to have 8 electrons in its outer shell, it loses negative charges. This makes
the atom positively charged. Positively charged ion are called cations. See the steps below for
making a sodium cation.
Lewis Structures of Ions: Draw Lewis Structures for the following IONS. (one of them doesn’t form an
ion)
9. Cl
10. H
11. O
13. S
14. Ca
15. F
12. Ar
16. Na
How to draw Lewis Structures of Ionic Compounds
(Problems 17-21)
Example: What molecule would form from Sodium ions and chlorine ions?
1.
Draw the lewis structure of a chlorine atom and a sodium atom.
2.
Convert the atoms to ions. But…
Electrons can’t just come from nowhere (that would violate the 1 st law of Thermodynamics!). So
when sodium loses an ion it must be transferred to the chlorine.
Draw the process of moving electrons from one atom to the other.
3.
Re-draw the lewis structure of the combined molecule. Include the charge of each ion.
4.
Sometimes this can be a little more difficult. Think of bonding aluminum to oxygen. Aluminum
wants to get rid of 3 electrons, but oxygen can only take 2.
Therefore, the last remaining electron must go to another oxygen atom. But this atom is still short
1 electron.
In order to make the oxygen have a full octet lets take an electron away from a second Aluminum
atom.
In order to make the aluminum have a full octet, it would have to lose another 2 electrons, so lets
add another oxygen atom
Now all 3 oxygen atoms have full octets and both aluminum atoms have full octets. Redraw the
ionic compound to make everything look neat. Add in charges.
Ionic Bonding: Draw the lewis structures of the following ionic compounds.
17.
Potassium and chlorine
18.
oxygen and aluminum
19.
magnesium and fluorine
20.
Bromine and Calcium
21.
Lithium and Sulfur
How to write the chemical formula of an ionic
compound(Problems 22-26)
Example:
Write the chemical formula of the compound made from fluorine and
magnesium
1. Draw the lewis structure of the compound that a fluorine atom and
a magnesium atom make.
Metal
Compound
Na
Nonmetal
Cl
Al
O
Al2O3
Mg
F
MgF2
NaCl
2.
Ionic compounds are made when metals and
non-metal bond together. Identify the metal
and and non-metal using the periodic table
3.
Write the atomic symbols of the two elements. The metal always goes first.
4.
Since there are 2 fluorine ions in one molecule of this compound, add a “2” subscript after the F.
Chemical formulae of ionic compounds: write the chemical formulae of the following ionic compounds
22.
Potassium and chlorine
Answer______________
23.
oxygen and aluminum
Answer______________
24.
magnesium and fluorine
Answer______________
25.
Bromine and Calcium
Answer______________
26.
Lithium and Sulfur
Answer______________
How to name ionic compounds(Problems 27-31)
Example: Name the compound made from chlorine and sodium.
1. Draw the lewis structure of the compound that a chlorine atom and a sodium atom make.
2.
Write the chemical formula of the compound that they make.
NaCl
3.
The first part of the name is just the metal.
Sodium
4.
The second part of the name is the nonmetal
Sodium chlorine
5.
Take away the last syllable of the non-metal and replace it with the “–ide” suffix.
Sodium chloride
Naming ionic compounds: name the following ionic compounds
27.
Potassium and chlorine
Answer______________
28.
oxygen and aluminum
Answer______________
29.
magnesium and fluorine
Answer______________
30.
Bromine and Calcium
Answer______________
31.
Lithium and Sulfur
Answer______________
Covalent Bonding
How to draw Lewis Structures of
Covalent Compounds (Problems 32-37)
Example: What molecule would form from 1 Carbon atom and unlimited
hydrogen atoms?
1.
Draw the lewis structure of a Carbon atom and a hydrogen atom.
Atom
Calcium
Carbon
Aluminum
Hydrogen
Metal or
Nonmetal
Metal
NonMetal
Metal
NonMetal
2.
Create a covalent bond between the carbon atom and the hydrogen atom. All covalent bonds are
between 2 or more non-metals (no metals are needed). In a covalent bond, electrons are shared.
Therefore a single bond counts as 2 electrons for both the carbon and the hydrogen.
3.
Follow the octet rule. Atoms are unstable until they have a full outer shell of electrons. For H
and He, this means that they have 2 electrons. For all other elements, this means that they have 8.
For this reason, Noble Gases do NOT form covalent bonds.
Our Hydrogen now has 2 valence electrons and is “happy” according to the octet rule.
Our Carbon has 3 single electrons and a single bond for a total of 5 electrons. It is NOT “happy.”
4.
Bond more hydrogen atoms on to the carbon atom until all the hydrogen atoms have 2 valence
electrons and the carbon atom has 8 valence electrons.
5.
Rewrite the lewis structure of the molecule to make it look neat.
Simple Covalent Bonding: Draw the lewis structures of the following covalent compounds.
32.
2 carbon atoms and unlimited hydrogen atoms
33.
Bromine and Oxygen
34.
1 Nitrogen atoms and unlimited hydrogen atoms
35.
Oxygen and hydrogen
36.
1 sulfur atom, 4 oxygen atoms and unlimited hydrogen atoms (tricky)
37.
Phosphorus and hydrogen
How to draw Lewis Structures of
Covalent Compounds using Double and
Triple bonds (Problems 38-43)
Example: What molecule would form from 1 Carbon atom and unlimited
oxygen atoms?
Bond
Single
Number
of
electrons
it holds
2
Double
4
Triple
6
1.
Draw the lewis structure of a Carbon atom and an Oxygen atom.
2.
Always start with the carbon atom (if there is one). Carbon often forms the “central atom” of
covalent compounds. Create a covalent bond between the carbon atom and the oxygen atom. In a
covalent bond, electrons are shared. Therefore the carbon is now surrounded by 5 electrons and
the oxygen is now surrounded by 7 electrons. According to the octet rule, neither atom is
“happy.”
3.
Create another covalent bond between the carbon atom and another oxygen atom. In a covalent
bond, electrons are shared. Therefore the carbon is now surrounded by 6 electrons and both
oxygens are now surrounded by 7 electrons. According to the octet rule, none of the atoms are
“happy.”
If we add two more oxygens the carbon will be “happy” but none of the oxygens will be. So this is not
possible
4.
There is a way that we can satisfy both the oxygens and the carbon. If we take the one of the extra
electrons on the carbon and share it with one of the extra electrons on one of the oxygens, we can
form a second bond. We now have a double bond.
5.
Take the last extra electron on the carbon and share it with the extra electron on one of the last
oxygen, we can form a second double bond. We now have 2 double bonds. Each double bond
counts as 4 electrons. All of our atoms now have 8 valence electrons.
6.
Rewrite the lewis structure of the molecule to make it look neat.
Advanced Covalent Bonding: Draw the lewis structures of the following covalent compounds.
38.
1 carbon atom, 2 oxygen atoms and unlimited hydrogen atoms
39.
1 sulfur atom, 1 nitrogen atom, 2 oxygen atoms, and 1 hydrogen atom
40.
1 Nitrogen atom, 1 hydrogen, and 1 carbon atom
41.
2 Carbon atoms and 2 hydrogen atoms
42.
Hydrogen, Oxygen, and Nitrogen
43.
2 Nitrogens
How to write the chemical formula of a covalent
compound(Problems 44-48)
Example: Write the chemical formula of the compound made from
Nitrogen and Bromine.
1. Draw the lewis structure of the compound that a Nitrogen atom
and bromine atoms make.
Nonmetal
C
Nonmetal
F
Compound
H
O
H2O
C
O
CO2
CF4
2.
Write the atomic symbols of the two elements. The central atom usually goes first.
3.
Since there are 3 bromine atoms in one molecule of this compound, add a “3” subscript after the
Br.
Chemical formulae of covalent compounds: write the chemical formulae of the following covalent
compounds
44.
Phosphorus and chlorine
Answer______________
45.
1 sulfur atom, 1 nitrogen atom, 2 oxygen atoms, and 1 hydrogen atom
Answer______________
46.
Oxygen and fluorine
Answer______________
47.
1 Carbon and 4 Hydrogens
Answer______________
48.
2 Nitrogens
Answer______________
How to name covalent compounds(Problems 49-53)
Example: Name the compound made from nitrogen and bromine.
1. Draw the lewis structure of the compound that nitrogen and bromine make.
2.
Write the chemical formula of the compound that they make.
3.
The first part of the name is just the central atom.
4.
The second part of the name is the second element with the “ide” suffix.
5.
Add in the latin prefix to denote the number of atoms.
Number
2
3
4
5
6
7
8
9
10
Naming covalent compounds: name the following covalent compounds
49.
1 carbon and 2 oxygens
Answer______________
50.
Hydrogen and Chlorine
Answer______________
51.
Oxygen and fluorine
Answer______________
52.
2 carbon atoms and 2 hydrogen atoms
Answer______________
53.
2 carbon atoms and 6 chlorine atoms
Answer______________
Prefix
Bi
Tri
Tetra
Penta
Hexa
Septa
Octa
Nona
Deca