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Chemical Formula and Equations


"The Atom"

Chemical Formula and Equations - What is a Chemical Formula?
Chemical Formulas are a type of shorthand for representing the elements in a compound. Element Symbols are included on the Periodic Table. Chemical symbols (Element symbols) from the periodic table are used for the individual elements e.g. H for hydrogen, C for carbon, O for oxygen, N for nitrogen, Ca for calcium and Na for Sodium. Substances that have two or more atoms bonded together, and therefore more than one element e.g. H2O are called compounds. See Examples of Compounds.

Chemical Formula and Equations - Subscripts
A chemical formula or equation shows the symbols of the elements in the compound and the ratio of the elements to one another. If a substance contains more than one atom of a particular element, this quantity is indicated in chemical formulas or equations using a subscript number after the element symbol.

The subscript number refers only to the element it immediately follows. For example, the chemical formula for water is H2O which indicates that 2 atoms of Hydrogen combines with 1 atom of oxygen.

How to write a Chemical Formula or Equation using Subscripts
To type or write a subscript for a chemical formula or equation just follow these simple instructions:

  • Type in the formula or equation for example H2O

  • Highlight the number

  • Click Format

  • Select Font... Decrease the font size of the number

  • Under the heading Effects tick the Subscript Box

  • The formula will now show the equation with the number in subscript - H2O

Chemical Formula and Equations - Examples and Meanings of Subscripts
For example, the chemical formula for water is H2O which indicates that 2 atoms of Hydrogen combines with 1 atom of oxygen. The chemical formula for sodium chloride (Salt) is NaCl indicating that one atom of sodium combines with one atom of chlorine in a one-to-one ratio. Subscripts are added, following the element symbol, to indicate that the number of atoms of that element in the compound if it is greater than one. For example, the formula for magnesium bromide MgBr2 which indicates that one magnesium atom combines with two bromine atoms.

Meanings and Examples of Chemical Formula and Equations
The following examples of Chemical Formula and Equations explain their meaning.

Example of Chemical Formula for Salt (Sodium Chloride) - NaCl


Symbol Na indicates the element Sodium
Symbol Cl indicates the element Chlorine
No subscripts indicate only 1 atom for each element

Example of Chemical Formula for Water - H2O


Symbol H indicates the element Hydrogen
Symbol O indicates the element Oxygen

Subscript indicates 2 atoms of Hydrogen

Chemical Formula and Equations - Common Chemical Formula List
The following list of Chemical Formula and Equations shows some of the most common chemical formulas.

Na : Sodium

H2O : Water

C6H12O6 : Glucose

C2H6O : Alcohol

CaSO4 : Sulfate Group

H2S : Hydrogen Sulfide

NaCl : Salt

O2 : Oxygen

C2H6O : Ethanol

C2H4O2 : Vinegar

NH3 : Ammonia

Mg : Magnesium

C2H4O2 : Acetic Acid

C4H10 : Butane

NO3 : Nitrate

Cu : Copper

N2 : Nitrogen

CO2 : Carbon Dioxide

H2SO4  : Sulfuric Acid

CH4 : Methane

C12H22O11 : Sucrose

C3H8 : Propane

NaHCO3 : Baking Soda

F : Fluoride

F2 : Fluoride

H2O2 : Peroxide

C8H10N4O2 : Caffeine

NaCl : Sodium Chloride

C9H8O4 : Aspirin

HCl : Hydrochloric Acid

Zn(NO3)2 : Zinc

CO : Carbon Monoxide

NaOH : Sodium Hydroxide

NaCN : Sodium Cyanide

Ca(CN)2 : Calcium Cyanide

Au : Gold

I : Iodine

Sn : Tin

C6H6 : Benzene

H2S : Hydrogen Sulfide

CH3COCH3 : Acetone

H3PO4 : Phosphoric Acid

C5H12 : Pentane

CH3OH : Methanol

HBr : Hydrobromic Acid

H2CO3 : Carbonic Acid

Ti : Titanium

NaClO : Sodium Hypochlorite

C2H6 : Ethane

(NH4)2SO4 : Ammonium Sulfate

C8H18 : Octane

CuSO4 : Copper Sulfate

C27H46O : Cholesterol

C7H6O2 : Benzoic Acid

H2SO3 : Sulfurous Acid

C6H12O6 : Galactose

C6H8O6 : Ascorbic Acid

CO2 : Dry Ice

NaNO3 : Sodium Nitrate

CaO : Calcium Oxide

HIO3 : Iodic Acid

C3H6O3 : Lactic Acid

MgBr2 : Lactic Acid

H2O : Water Vapor

C : Carbon

H : Hydrogen

CnH2nOn : Sugar

O4S2-  : Sulfate

N2O : Nitrogen

C6H8O7 : Citric Acid

C8H18 : Octane

C10H16O : Camphor

AgI : Silver Oxide

As4O3 : Arsenic Trioxide

Au2O3 : Gold Trioxide

Au2S : Gold Sulfide

Br2 : Bromine

Al2O3 : Aluminium foil

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