–       In 1817, Jakob Berzelius created an international system to represent all elements with symbols.

–       We still use his system today (all over the world), which involves elements being represented by one or two letters found in their name.  The first letter is always capitalized.  If there is a second letter, it is always a small letter.

–       Different countries may have different words or spellings for elements, but everyone uses the same symbols.

CHEMICAL SYMBOLS

–       You can probably see why carbon has the symbol C and nitrogen has the symbol N, but why does sodium have the symbol Na?

–       Some symbols are short forms for element names in different languages, mostly Latin.

–       Let’s look at some examples:

ELEMENT NAME	ELEMENT SYMBOL	NAME AND LANGUAGE
Sodium	Na	Natrum, Latin
Potassium	K	Kalium, Latin
Iron	Fe	Ferrum, Latin
Gold	Au	Aurium, Latin
Tungsten	W	Wolfram, German
Lead	Pb	Plumbum, Latin

–       Some other elements have been named for locations around the world, such as:

ELEMENT NAME	ELEMENT SYMBOL	LOCATION NAMED FOR
Germanium	Ge	Germany
Francium	Fr	France
Polonium	Po	Poland
Neptunium	Np	Neptune (8th planet)

–       Other elements have been named after famous scientists:

ELEMENT NAME	ELEMENT SYMBOL	FAMOUS SCIENTIST
Einsteinium	Es	Albert Einstein
Curium	Cm	Marie and Pierre Curie
Nobelium	No	Alfred Nobel
Rutherfordium	Rf	Ernst Rutherford
Fermium	Fm	Enrico Fermi

CHEMICAL FORMULAS

–       When we put elements together, we can create countless different chemicals.  The chemicals are then given symbols depending on which elements make up each new chemical.  The combination of element symbols is called a chemical formula.

–       A chemical formula let’s us know which elements and how many of each element are present in a specific chemical.

–       For example, the chemical formula NaCl represents salt (it’s chemical name is sodium chloride).  Which two elements make up salt?  Sodium and chlorine.

–       In each molecule of salt, one atom of sodium is combined with one atom of chlorine.  No numbers are required in this formula because only one atom of each element is involved in making salt.

–       If more than one atom of an element is involved in a chemical, a number must be included in the chemical formula.  The numbers in chemical formulas are called subscripts.  Subscripts are small numbers written below the letters.

–       For example, the chemical formula for water is H₂O.  This formula means that each molecule of water contains two atoms of hydrogen and one atom of oxygen.  The small 2 after the H represents two hydrogen atoms.

–       Let’s look at a few more chemical formulas:

• The formula for chalk (calcium carbonate) is CaCO₃.
  • What atoms (and how many) make up chalk?
    • 1 Calcium
    • 1 Carbon
    • 3 Oxygen

• Vinegar (acetic acid) has the following formula: C₂H₄O₂.
  • How many of each atom is in vinegar?
    • 2 Carbon
    • 4 Hydrogen
    • 2 Oxygen

–       Sodium bicarbonate (baking soda) has a formula that consists of 1 sodium atom, 1 hydrogen atom, 1 carbon atom, and 3 oxygen atoms.  What is the formula of baking soda?

• NaHCO₃

–       Sometimes brackets are used when writing formulas.  Any number outside of the bracket multiplies everything inside of the bracket by that number.  For example, the formula for calcium phosphate (a fertilizer) is Ca₃(PO₄)₂.  How many of each atom are in calcium phosphate?

• 3 Calcium
• 2 Phosphorus
• 8 Oxygen

–       Let’s try another one: Aluminum sulfate has a formula of Al₂(SO₄)₃.  How many of each atom are in aluminum sulfate?

• 2 Aluminum
• 3 Sulfur
• 12 Oxygen