Name
KEY
Date
Pd
Chemistry – Unit 6 Worksheet 1
When Metal-Non-Metal (ionic) compounds are dissolved, the metal particles tend to form
positively charged ions (cations) as evidenced by their attraction to a negative electrode, while
non-metal particles tend to form negatively charged ions (anions) and migrate to a positively
charged electrode. We will now examine the patterns that exist for the ratios in which these
elements combine in order to determine the charges of the ions they form.
1. Write the formula, draw a particle diagram for each compound, and name it.
The ratio of ions in each compound is given. When naming ionic compounds, we simply write
the name of the first (the metal) element and then the second (non-metal) element, but change
the ending to –ide. See the completed names below. Note that no prefixes are used.
Atoms
involved
formula
1 calcium
1 oxygen
2 lithium
1 oxygen
CaO
2 aluminum
3 sulfur
1 beryllium
1 sulfur
Al2S3
BeS
Li2O
particle
diagram
name
calcium oxide
Atoms
involved
formula
2 boron
3 oxygen
lithium oxide
aluminum sulfide
1 magnesium
1 oxygen
B2O3
2 sodium
1 sulfur
MgO
beryllium sulfide
3 sodium
1 nitrogen
Na2S
Na3N
particle
diagram
name
Atoms
involved
formula
boron oxide
1 magnesium
2 chlorine
magnesium oxide
1 lithium
1 fluorine
MgCl2
sodium sulfide
1 beryllium
2 bromine
LiF
1 aluminum
3 bromine
BeBr2
AlBr3
beryllium
bromide
aluminum
bromide
sodium nitride
1 sodium
1 fluorine
NaF
particle
diagram
name
magnesium
choride
lithium
fluoride
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sodium
fluoride
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Atoms
involved
formula
1 sodium
1 chlorine
1 calcium
2 bromine
NaCl
1 aluminum
3 chlorine
CaBr2
3 potassium
1 phosphorus
3 magnesium
2 phosphorus
AlCl3
K3P
Mg3P2
aluminum
chloride
potassium
phosphide
magnesium
phosphide
particle
diagram
name
sodium
chloride
calcium
bromide
2. Write each formula from Question 1 in the boxes corresponding to its elements. For example,
the compound formed from sodium and sulfur have been written in the box for sodium and in
the box for sulfur. Now add the rest.
Hydrogen
1
Helium
2
H
Lithium
3
He
Beryllium
4
Boron
5
Li
Li2O
LiF
Be
BeS
BeBr2
B
B2O3
Sodium
11
Magnesium
12
Aluminum
13
Na
Na2S
Na3N
NaF
NaCl
Potassium
19
K
K3P
Carbon
6
C
Silicon
14
Mg
MgO
MgCl2
Mg3P2
Al
Al2S3
AlBr3
AlCl3
Si
Calcium
20
Gallium
31
Germanium
32
Ca
CaO
CaBr2
©Modeling Instruction – AMTA 2013
Ga
Ge
2
Nitrogen
7
N
Na3N
Phosphorus
15
P
K3P
Mg3P2
Arsenic
33
As
Oxygen
8
Fluorine
9
Neon
10
Chlorine
17
Al2S3
BeS
Cl
MgCl2
NaCl
AlCl3
Argon
18
Selenium
34
Bromine
35
Krypton
36
O
CaO
Li2O
B2O3
MgO
Sulfur
16
S
Na2S
Se
F
LiF
NaF
Br
BeBr2
AlBr3
CaBr2
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Ne
Ar
Kr
3. What patterns do you find in the formulas of the compounds formed in the table in #2?
Elements in groups 1A and 7A combine in a 1:1 ratio, 2A and 7A in a 1:2 ratio, 3A and 7A in a 1:3 ratio. Elements in 2A and 6A
combine in a 1:1 ratio, 3A and 6A in a 2:3 ratio.
Based on these patterns, predict the formulas of the compounds formed by the ions below.
Ratio of ions in compound
Atoms
___ potassium ___ calcium
___ gallium
___ magnesium
involved
___ oxygen
___ sulfur
___ oxygen
___ fluorine
Ga2O3
MgF2
formula
K2O
CaS
4. How does a neutral atom become a positive ion? a negative ion?
A neutral atom must lose electrons to become a positive ion. It must gain electrons to become negative.
5. Do the elements in group 1A behave more like top or bottom tape? How about the elements in
group 7A? How so?
Metals tend to lose electrons making them (+) charge, like the top tape. Elements in group 7A are non-metals and would gain
electrons. This makes them like the bottom tape.
6. Make whatever generalizations you can about the charge of the ions formed by elements in
columns 1A, 2A, 3A and 7A based on the ratio of atoms in each of the compounds they form.
Group I forms +1 ions, group 2A forms +2 ions, group 6A forms -1 ions and group 7A forms -1 ions. “But what if group 2A were
+1”. Then that group 7A would have to have a charge of -1/2, and that fractional charge is unlikely.
7. Using the fact that compounds are also neutral, account for the fact that the ions combine in
the ratios you have listed in the table in #2. Provide a couple of specific examples to support
your explanation.
Ions combine is such a way as to form compounds that are electrically neutral. Two =1 Li ions combine with one -2 oxide ion to
form lithium oxide, Li2O. The Al+3 ion combines with 3 Cl-1 ions to form the neutral AlCl3
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