Grade 9 Chemistry – Topics 4-6 Review (ANSWERS)
1. How can you tell if a compound is ionic or molecular simply by looking at the periodic table?
If a substance is IONIC, it is made of a METAL (+) and a NON METAL (-). If a substance is
MOLECULAR, it is made of 2 NON METALS (-)
2. Summarize the rule for naming ionic compounds, and give an example.
1) Name the METAL first (full name, no changes)
2) Name the NON METAL second, change the ending to “ide”
EXAMPLE: Lithium and Chlorine
Li = 1+, Cl = 1- (NOTE** the 1+ and 1- create a neutral compound, perfectly balanced)
NAME: Lithium chloride
3. Why do molecular compounds require prefixes for number of atoms, when ionic compounds do
not? Nonmetals may combine in a variety of ratios, so it is important that the name of a
molecular compound indicates how many atoms of each type of element are present in the
compound. This is accomplished using prefixes. If there is only one atom of the first element,
no prefix is used. It is customary to prefix the name of one atom of the second element with
mono-. For example, CO is named carbon monoxide rather than carbon oxide.
4. What are the prefixes for molecular compounds?
1 atom __________________MONO
2 atoms _________________DI
3 atoms _________________TRI
4 atoms _________________TETRA
5. Summarize the rule for naming molecular compounds and give an example.
You can write the formula for a covalent compound from its name by
1) writing the symbols for the first and second element
2) translate the prefixes into subscripts.
For example, xenon hexafluoride would be written XF6.
It is common for students to confuse ionic compounds and covalent compounds and then have
trouble trying to write formula from the compounds names. You aren't balancing charges of
covalent compounds; if the compound does not contain a metal, don't try to balance this!
6. What is the exception to the prefix rule for molecular compounds?
When the first metal has only 1 atom, you do not call it “MONO” _________
Example: CO2 = Carbon dioxide, NOT Monocarbon dioxide
7. What is a polyatomic ion?
A compound that consist of two or more atoms with one overall charge
8.
When naming polyatomic compounds, CO3 is called carbonate and SO4 is called sulfate. When
you see “ate” instead of “ide” at the end of a compound name, you know it is a polyatomic
compound.
Name these two compounds:
Na2O = Sodium oxide
Na2SO4 = Sodium sulfate
9. Name the following compounds:
BeSO4 ______________________________ ( I ) Beryllium sulphate
P2S3
______________________________ ( M ) Diphosphorus trisulfide
AlCl2
______________________________ ( I ) Aluminum chloride
N2O3
______________________________ ( M ) Dinitrogen trioxide
Mg3P2 ______________________________ ( I ) Magnesium phosphide
BeBr2
______________________________ ( I ) Beryllium bromide
CCl4
______________________________ ( M ) Carbon tetrachloride
10. Write chemical formulas for the following compounds. Circle the letter “I” if the compound is
ionic and “M” if the compound is molecular.
Difluorine oxide ______________________
( M ) F2O
Carbon monoxide ____________________
( M ) CO
Lithium bromide_____________________
( I ) LiBr
Magnesium carbonate _______________
( I ) MgCO3
Aluminum sulfide_____________________
( I ) Al2S3
Chlorine trifluoride ___________________
( M ) ClF3
Sodium hydride ______________________
( I ) NaH
11. What do subscript, italicized letters after a formula mean? Specifically identify what (s), (l), (g)
and (aq) mean.
Solid, Liquid, Gas, Aqueous
12. What are the chemical formulas for the following common household compounds?
Table salt _________________________ NaCl
Sugar _____________________________ C12H22O11
Rust ______________________________ Fe2O3
Water _____________________________ H2O
13. Explain the difference between an element symbol, a chemical formula, and a chemical
equation. Give an example of each.
Element symbol: Abbreviations that are used to denote a chemical element. Typically, they are
one or two-letters long with the first letter (only) capitalized.
Chemical formula: A way of expressing information about the atoms that constitutes a
compound.
It identifies each element by its symbol and shows the number of atoms of each element found
in each molecule of that compound. If a molecule contains more than one atom of a particular
element, this quantity is indicated using a subscript after the chemical symbol
Chemical equation: A chemical equation is a written representation of the process that occurs
in a chemical reaction. A chemical equation is written with the reactants on the left side of an
arrow and the products of the chemical reaction on the right side of the equation.
14. Write formulas for compounds formed when the following elements combine:
Lithium and Fluorine _______________________________ LiF
Beryllium and Chlorine _____________________________BeCl2
Sodium and Nitrogen ______________________________Na3N
Magnesium and sulfur _____________________________MgS
15. What is the difference between a “Group” and a “Period” on the periodic table?
A group is a vertical column within the periodic table, a period is a horizontal row in the periodic table
16. Highlight/Colour the periodic table with the following:
 Alkali Metals = Pink
 Alkali Earth Metals = Blue
 Halogens = Green
 Nobel Gases = Yellow
 Metalloids = Orange
Fill in the following chart.
Chemical Formula
Chemical Name
1.
Li3N
Lithium nitride
2.
BeO
Beryllium oxide
3.
Rb2Se
Rubidum selenide
4.
ScP
Scandium phophide
5.
CaF2
Calcium fluoride
6.
AuI3
Gold (III) Iodide
7.
Pb(ClO2)2
Lead (II) chlorite
8.
MnBr4
Manganese (IV) bromide
9.
Ba(MnO4)2
Barium permanganate
10.
Ra3N2
Radium nitride
Molecular Bonding Practice #2
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
C2F4
Dicarbon tetrafluoride
N3O2
Trinitrogen dioxide
P5Cl
Pentaphosphorous monochloride
BBr3
Boron tribromide
Se4I2
Tetraselenium diiodide
N2F5
Dinitrogen pentafluoride
Si4P2
Tetrasilicon diphosphide
As5N4
Pentaarsenic tetranitride
P2S3
Diphosphorous trisulfide
S3Cl3
Trisulfur trichloride