1. Elements, Compounds, and Mixtures

2. First, we need a brief review
First, we need a brief review! So far, we have learned that an atom has a nucleus containing protons and neutrons, and is surrounded by a cloud of electrons.
When atoms share or trade electrons, they form BONDS. Two or more atoms bonded together is called a MOLECULE.

3. Chemists show that atoms are bonded together using the symbols below
Two hydrogen atoms bonded together
H H H
H C H
One carbon and four hydrogen atoms bonded together

4. Since this molecule contains two of the same type of atom, this is an ELEMENT.
H H H
H C H
Since this molecule contains two different types of atoms, this is a COMPOUND.

5. Chemical bond. Carbon and hydrogen are sharing electrons.
Notice that in a compound, the different atoms are connected by chemical bonds. H
H C H
Chemical bond. Carbon and hydrogen are sharing electrons.

6. In a MIXTURE, the atoms or molecules are NOT connected by chemical bonds.
H H
C H
C H

7. On your paper, write down which letter is an element, which letter is a compound, and which letter is a mixture. A B C

8. On your paper, write down which letter is an element, which letter is a compound, and which letter is a mixture.
O H
O H O
H H
O O H
H__H
H__H H__H
H__O__H
H_O_H A B C