Chemical FormulaChemical Formula

atomatom

moleculemoleculecompound

ex: H20, NaCl

elementelement

O OO O22

matter

symbol - p 20•usually 1 or 2 letters that are used to identify an element

•only 1st letter is capitalized (ex: He - helium)

symbol

hydrogenhydrogen

HH

CoCoCOCO

Co - cobalt

CO - carbon, oxygen

formula - p 20• a combination of symbols that shows the ratio of elements in a compound

• Ex: HEx: H22O, the ratio of O, the ratio of

Hydrogen to Oxygen is 2:1Hydrogen to Oxygen is 2:1

formula

Example (add to notes on formula)

• CHCH44 (methane) (methane)

• 1:4 ratio1:4 ratio• 1 Carbon atom: 4 Hydrogen atoms1 Carbon atom: 4 Hydrogen atoms

Word Equations

A word equation gives the names of the substances involved in a reaction. For example:

copper + oxygen → copper oxidecopper + oxygen → copper oxide

Copper and oxygen are the reactants, and copper oxide is the product.

Chemical EquationsChemical equations give the symbols and molecular formula of the substances involved in a reaction. In the example below, if we just replace the words shown below with the correct chemical formula, we will get an unbalanced equation, as shown here:copper + oxide yields copper oxide

Cu + OCu + O2 2 → CuO → CuO

Chemical equations give the symbols and molecular formula of the substances involved in a reaction. In the example below, if we just replace the words with the correct chemical formula, we will get an unbalanced equation, as shown here:

Copper + oxygen yields copper oxide

Cu + O2 → CuO To make things equal, we need to adjust the number

of units of some of the substances until we get equal numbers of each type of atom on both sides of the arrow.

Here is the balanced chemical equation:

2Cu + O2 → 2CuO

2Cu + O2 2CuO

atomsatoms

twotwo

ElementsElements compoundscompounds

fewerfewer

largerlarger

threethree

threethree

1010

2121

more than a billionmore than a billion

bb

cc

ee

aadd

22 sulfursulfuroxygenoxygen

11

2233

22 nitrogennitrogen

hydrogenhydrogen11

3344

66

4545

66

33

44

hydrogenhydrogen

carboncarbonoxygenoxygen

hydrogenhydrogenoxygenoxygen

carbon carbon

hydrogenhydrogen oxygenoxygen

magnesiummagnesium sulfursulfur oxygenoxygen

sodium sodium oxygen oxygen

hydrogenhydrogen

3322

11

331212

2222

1111

11

11

11

11

11

44

22

22

33

33

22

33

55

66

22

44

iron iron oxygenoxygen

22

33

11

11

11

33

sodium sodium hydrogen hydrogen

carbon carbon oxygenoxygen