Elements, Compounds, and Mixtures

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.

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

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.

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.

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

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

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