# 2.15: Chemical Symbols and Formulas


### How do chess players monitor their moves in a game?

Suppose you were walking along and noticed a piece of paper on the ground with markings on it. You pick it up and see the paper in the picture above.

To most people, these notes are meaningless (maybe they're a secret spy code). But to a chess player, these symbols tell the story of a chess game. Each abbreviation describes a chess piece or a move during the game. The use of special symbols allows chess players to "see" the game without having to read a wordy and possibly incomplete description of what happened.

## Chemical Symbols and Formulas

### Chemical Formula

In order to illustrate chemical reactions and the elements and compounds involved in them, chemists use symbols and formulas. A chemical symbol is a one- or two-letter designation of an element. Some examples of chemical symbols are $$\ce{O}$$ for oxygen, $$\ce{Zn}$$ for zinc, and $$\ce{Fe}$$ for iron. The first letter of a symbol is always capitalized. If the symbol contains two letters, the second letter is lower case. The majority of elements have symbols that are based on their English names. However, some of the elements that have been known since ancient times have maintained symbols that are based on their Latin names, as shown below.

Chemical Symbol Name Latin Name
Table 1: Symbols and Latin Names for Elements
$$\ce{Na}$$ Sodium Natrium
$$\ce{K}$$ Potassium Kalium
$$\ce{Fe}$$ Iron Ferrum
$$\ce{Cu}$$ Copper Cuprum
$$\ce{Ag}$$ Silver Argentum
$$\ce{Sn}$$ Tin Stannum
$$\ce{Sb}$$ Antimony Stibium
$$\ce{Au}$$ Gold Aurum
$$\ce{Pb}$$ Lead Plumbum

### Chemical Formulas

Compounds are combinations of two or more elements. A chemical formula is an expression that shows the elements in a compound and the relative proportions of those elements. Water is composed of hydrogen and oxygen in a two to one ratio. The chemical formula for water is $$\ce{H_2O}$$. Sulfuric acid is one of the most widely produced chemicals in the United States and is composed of the elements hydrogen, sulfur, and oxygen. The chemical formula for sulfuric acid is $$\ce{H_2SO_4}$$.

## Summary

• A chemical symbol is a one- or two-letter designation of an element.
• Compounds are combinations of two or more elements.
• A chemical formula is an expression that shows the elements in a compound and the relative proportions of those elements.
• Some elements have symbols that derive from the Latin name for the element.

## Review

1. What is a chemical symbol?
2. What is a chemical formula?
3. How many hydrogen atoms are in one molecule of the compound C12H22O11?
4. What is the Latin name for the element potassium?

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