Page 56 - Curriculum Visions Dynamic Book

Understanding equations
As you read through Volumes 1 to 15 in the Elements set, you will notice that many pages contain equations using symbols. Symbols make it easy for chemists to write out the reactions that are occurring in a way that allows a better understanding of the processes involved. If you are not familiar with these symbols, these pages explain them.
Symbols for the elements
The basis for the modern use of symbols for elements dates back to the 19th century.At that time a shorthand was developed using the first letter of the element wherever possible.
Written and symbolic equations
Thus O stands for oxygen, H stands for hydrogen, and so on. However, if we were to use only the first letter, there could be some confusion. For example, nitrogen and nickel would both use the symbols N.To overcome this problem, many element symbols take the first two letters of the full name, with the second letter in lower case. So, although nitrogen is N, nickel becomes Ni. Not all symbols come from the English name; many use the Latin name instead.That is why, for example, gold is not G but Au (from the Latin aurum), and sodium has the symbol Na (from the Latin natrium).
Compounds of elements are made by combining letters. So, the molecule carbon
In this book important chemical equations are briefly stated in words (they are called word equations) and are then shown in their symbolic form along with the states.
What reaction the equation illustrates
Word equation
Symbol equation
EQUATION: The formation of calcium hydroxide
Calcium oxide + water ➪ calcium hydroxide
CaO(s) +
H2O(l)
➪
heated
Ca(OH)2(aq)
Symbol showing the state:
s is for solid, l is for liquid,
g is for gas, and aq is for aqueous.
Diagrams
Sometimes you will find additional descriptions below the symbolic equation.
Some of the equations are shown as graphic representations.
Oxygen
Hydrogen
Calcium
Calcium oxide Water
Calcium hydroxide
Sometimes the written equation is broken up and put below the relevant stages in the graphic representation.
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