DO NOW Open your notebook, ready to take notes. Answer this question in your notebook: What is the difference between an element and a compound? Reminder: Isotopes Lab due Friday

ELEMENTS, COMPOUNDS, AND MIXTURES

An element is a substance composed of a single kind of atom

Example: Aluminum

- Atoms are the basic particles of an element. Different elements have different properties because their atoms are different

When atoms combine they form a chemical bond, a force or attraction between two atoms. In most cases, atoms combine to form larger particles called molecules.

Example: A molecule of water consists of an oxygen atom chemically combined to two hydrogen atoms.

- Compound: 2 or more elements chemically combined in a set ratio

A compound may be represented by a chemical formula, which shows the elements in the compound and the ratio of the atoms. Example: Carbon Dioxide

When elements are chemically combined, they form compounds having properties that are different from those of the uncombined elements!

Example: A snail’s shell is composed of calcium, carbon, and oxygen

Number of Elements H2O  Made of two different elements Example: H2O  Made of two different elements Hydrogen, Oxygen C6H12O6  How many different elements? Three! Carbon, Hydrogen, Oxygen

The subscript is the number written to the right of a chemical symbol and slightly below it.