Grade 9 Science – Unit 1 Lesson 9

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Grade 9 Applied Science – Chemistry
Chemical Symbols and Formulas
Chemical Symbols
You have learned that an element is a PURE SUBSTANCE that is made of the same atoms with
definitive Physical and Chemical Properties. Chemical Symbols are used to identify each element.
 Each Chemical Symbol is an ABBREVIATION of the name of the element. The abbreviation
consists of one or two letters.
 The names and symbols for the elements come from many sources including Latin and Greek
languages. For example, the symbol for silver is Ag because the Latin name for silver is
argentium. The symbol for mercury is Hg because the Latin name for mercury is hydragyrum
meaning liquid silver.
Table 1. Elemental Name and Chemical Symbol for Some of the First 20 Elements of the Periodic Table
Elemental Name
Atomic Number
Chemical Symbol
Hydrogen
1
H
Helium
2
He
Carbon
6
C
Nitrogen
7
N
Oxygen
8
O
Sodium
11
Na
Aluminum
13
Al
Silicon
14
Si
Chlorine
17
Cl
Potassium
19
K
Chemical Formula
Chemical Symbols can be combined to identify CHEMICAL COMPOUNDS.
 Table salt is a compound composed of Sodium (Na) and Chlorine (Cl). The Chemical Formula
for table salt is NaCl. These two elements bond together because one element gives an electron
(Na) while the other element takes the electron (Cl). This type of bond is called an IONIC BOND.
In this example, one atom of sodium combines with one atom of chlorine
 In water, there are TWO hydrogen atoms and one atom of oxygen bonded together. In a
Chemical Formula, a subscript number indicates how many of each element is present.
For example, H2O tells us there are two hydrogens and one oxygen.
PRACTICE
Use the chemical formula to determine the number of each element in the chemical compound
Compound Name
Chemical Formula
Ammonia
NH3
Sodium bicarbonate
NaHCO3
Acetic Acid (vinegar)
C2H4O2
Sodium nitrate
NaNO3
Acetylsalicylic acid
(aspirin)
C9H8O4
Calcium carbonate
(chalk)
CaCO3
Glucose (sugar)
C6H12O6
Calcium phosphate
Ca3(PO4)2
Number of Each Element
ANSWERS
Compound Name
Chemical Formula
Number of Each Element
Ammonia
NH3
1 Nitrogen; 3 Hydrogen
Sodium bicarbonate
NaHCO3
1 Sodium, 1 Hydrogen, 1 Carbon and 3 Oxygen
Acetic Acid (vinegar)
C2H4O2
2 Carbon, 4 Hydrogen and 2 Oxygen
Sodium nitrate
NaNO3
1 Sodium, 1 Nitrogen and 3 Oxygen
Acetylsalicylic acid
(aspirin)
C9H8O4
9 Carbon, 8 Hydrogen and 4 Oxygen
Calcium carbonate
(chalk)
CaCO3
1 Calcium, 1 Carbon and 3 Oxygen
Glucose (sugar)
C6H12O6
6 Carbon, 12 Hydrogen and 6 Oxygen
Calcium phosphate
Ca3(PO4)2
3 Calcium, 2 Phosphorus and 8 Oxygen
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