What is Chemical formula?
A '''chemical formula''' is a way that chemists describe a [[molecule]]. The formula says what [[atom]]s, and how many of each type, are in the molecule. Sometimes the formula shows how the atoms are linked, and sometimes the formula shows how the atoms are arranged in space. The letter shows what [[chemical element]] each atom is. These are called [[chemical symbol]]s and they are one or two letters long.<ref>{{Cite web|url=http://www.chemicalelements.com/|title=chemical elements|first=|last=|website=|publisher=|accessdate=June 8, 2016}}</ref> The [[subscript]] shows the number of each type of atom. For example, [[methane]] has one [[carbon]] (C) atom and four [[hydrogen]] atoms; the chemical formula is CH<sub>4</sub>. The [[sugar]] molecule [[glucose]] has six carbon atoms, twelve hydrogen atoms, and six [[oxygen]] atoms, so its chemical formula is C<sub>6</sub>H<sub>12</sub>O<sub>6</sub>. Chemical formulas are used in [[chemical equation]]s to describe [[chemical reaction]]s. The 19th-century Swedish chemist [[Jöns Jacob Berzelius]] worked out this system for writing chemical formulas. == Reading and writing formulas == Chemical formulas are another way to represent the number of atoms.<ref>{{Cite web|url=http://www.chem1.com/acad/webtext/intro/int-3.html|title=Chemical Formula and their Arithmetic|first=|last=|website=|publisher=|accessdate=June 6, 2016}}</ref> Chemical formulas are used to represent kinds of atoms in a combination. Chemical formulas use subscripts to tell how many of each atom are present in a combination. Subscripts are small numbers to the lower right of a symbol. They represent the number of atoms of that element in the equation. Before writing Chemical formulas, write down the symbol of each atom present in your equation. Writing chemical formula is a way of informing the chemical figure. It is most easily found in the periodic table. The periodic table is a chart of all well-known parts. Use the periodic table to reference the figure that cannot be remembered.<ref>{{cite book |title