TNPSC Chemistry - Elements and compounds(symbols)
What is symbol? :
Symbols are used to represent names of elements.
A symbol is a shortened form of the name of an element.
Let us learn the brief history of symbols of elements.
GREEK SYMBOLS:
Some earliest symbols in form of geometrical shapes were those used by the ancient Greeks to represent the four elements earth,air,fire and water.
ALCHEMIST SYMBOLS:
In the days of alchemist, the different materials that they used were represented by pictorial symbols.
The work of trying to change less valuable metal into gold was called alchemy, and the men who did this work were alchemists.
DALTON'S SYMBOLS:
In 1808, John Dalton, English scientists tried to name the various elements based on these pictorial symbols.
The uses of the above symbols are difficult to draw and inconvenient to use. Hence, Dalton, symbols are not used; it is only of historical importance.
BERZELIUS SYMBOLS:
In 1813, Jon Jakob Berzelius, Swedish chemist devised a system using letters of alphabet. He argued that letters should be used because they could be written more easily than other signs. The modified version of Berzelius system follows under the heading
System for Determining Symbols of the Elements:
1. The symbols of the most common elements, mainly non-metals, use the first letter of their English name.
Element. Symbol
Boron. B
Carbon. C
Hydrogen. H
Iodine. I
2. If the name of the element has the same initial letter as another element, then symbol uses the first and second letters of their English name.
Element. Symbol
Aluminum. Al
Barium. Ba
Beryllium. Be
Bismuth. Bi
Bromine. Br
Cobalt. Co
3. If the first two letters of the names of elements are the same, then the symbol consists of first letter and second or third letter of English name that they do not have in common.
Element. Symbol
Argon. Ar
Arsenic. As
Chlorine. Cl
Chromium. Cr
Calcium. Ca
Cadmium. Cd
4. Some symbols are based on the old names or Latin name of the element. There are eleven elements.
Element. Latin name. Symbol
Sodium. Natrium. Na
Potassium. Kalium. K
Iron. Ferrum. Fe
Copper. Cupurum cu
Silver. Argentum. Ag
Gold. Aurum. Au
Mercury. Hydrargyrum. Hg
Lead. Plumbum. Pb
Tin. Stannum. Sn
Antimony. Stibium. Sb
Tungsten Wolfram. W
5. Names of some elements are derived from important country, scientist, colour, mythological character, planet.
How to write a symbol?
a. If the element has a single English letter as a symbol, it should be written in capital letter.
b. For elements having two letter symbols, the first letter should be in capital followed by small letter.
Significance of the symbol of an element:
a. Name of the element
b. One atom of the element
For example,
a. The symbol of N stands for the element of nitrogen
b. One atom of nitrogen
Molecule of an element:
The molecule of an element contains two or more similar atoms. For example, a molecule of chlorine contains two atoms of chlorine; it is therefore written as Cl2 (Chlorine).
Monoatomic molecule - Helium, Neon, Argon, Krypton etc,.
Diatomic molecule - Oxygen, Nitrogen, Chlorine, Fluorine etc,.
Triatomic molecule - O3 (Ozone)
Polyatomic molecule - P4 (Phosphorus), S8 (Sulphur).
Symbols are used to represent names of elements.
A symbol is a shortened form of the name of an element.
Let us learn the brief history of symbols of elements.
GREEK SYMBOLS:
Some earliest symbols in form of geometrical shapes were those used by the ancient Greeks to represent the four elements earth,air,fire and water.
ALCHEMIST SYMBOLS:
The work of trying to change less valuable metal into gold was called alchemy, and the men who did this work were alchemists.
DALTON'S SYMBOLS:
In 1808, John Dalton, English scientists tried to name the various elements based on these pictorial symbols.
The uses of the above symbols are difficult to draw and inconvenient to use. Hence, Dalton, symbols are not used; it is only of historical importance.
BERZELIUS SYMBOLS:
In 1813, Jon Jakob Berzelius, Swedish chemist devised a system using letters of alphabet. He argued that letters should be used because they could be written more easily than other signs. The modified version of Berzelius system follows under the heading
System for Determining Symbols of the Elements:
1. The symbols of the most common elements, mainly non-metals, use the first letter of their English name.
Element. Symbol
Boron. B
Carbon. C
Hydrogen. H
Iodine. I
2. If the name of the element has the same initial letter as another element, then symbol uses the first and second letters of their English name.
Element. Symbol
Aluminum. Al
Barium. Ba
Beryllium. Be
Bismuth. Bi
Bromine. Br
Cobalt. Co
3. If the first two letters of the names of elements are the same, then the symbol consists of first letter and second or third letter of English name that they do not have in common.
Element. Symbol
Argon. Ar
Arsenic. As
Chlorine. Cl
Chromium. Cr
Calcium. Ca
Cadmium. Cd
4. Some symbols are based on the old names or Latin name of the element. There are eleven elements.
Element. Latin name. Symbol
Sodium. Natrium. Na
Potassium. Kalium. K
Iron. Ferrum. Fe
Copper. Cupurum cu
Silver. Argentum. Ag
Gold. Aurum. Au
Mercury. Hydrargyrum. Hg
Lead. Plumbum. Pb
Tin. Stannum. Sn
Antimony. Stibium. Sb
Tungsten Wolfram. W
5. Names of some elements are derived from important country, scientist, colour, mythological character, planet.
How to write a symbol?
a. If the element has a single English letter as a symbol, it should be written in capital letter.
b. For elements having two letter symbols, the first letter should be in capital followed by small letter.
Significance of the symbol of an element:
a. Name of the element
b. One atom of the element
For example,
a. The symbol of N stands for the element of nitrogen
b. One atom of nitrogen
Molecule of an element:
The molecule of an element contains two or more similar atoms. For example, a molecule of chlorine contains two atoms of chlorine; it is therefore written as Cl2 (Chlorine).
Monoatomic molecule - Helium, Neon, Argon, Krypton etc,.
Diatomic molecule - Oxygen, Nitrogen, Chlorine, Fluorine etc,.
Triatomic molecule - O3 (Ozone)
Polyatomic molecule - P4 (Phosphorus), S8 (Sulphur).
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