Elements are different types of atoms. They can be represented with their chemical symbol (which are just letters). Take a look at the periodic table below.
You will see each square is a different element (type of atom). Some elements have a single capital letter, while others have a capital letter and a lower case letter. For example, Boron has a chemical symbol of B. Neon has a chemical symbol of Ne.
Compounds are two or more different types of atoms that are chemically bonded together.
When we write them together in a chemical formula unit, we are saying they are chemically bonded.
Look at the examples of compounds below.
1) The first example has a capital H and a capital O. These letters are different, and written together, so that means they are chemically bonded. If you look at the picture you will see the atoms are touching to indicate they are chemically combined.
2) The second examples has a capital C and a capital O. These letters are different, and written together, so that means they are chemically bonded.
Just a reminder, the little number is called a subscript. It tells you how many atoms of each type of element you have. The little number belongs with the capital in front of it. If there is no number, that means you have only 1 atom of that element.
When reading chemical formula units to determine if they are an element or compound, use the following questions:
Is there more than one type of capital letter?
If the answer is yes, then it is a compound.
If the answer is no, then it is an element.
Instructions:
Complete the following worksheet by identifying each chemical formula unit as an element or compound: