<p>Compound Notes</p><p>An element is a part of matter made of only one type of atom. Elements can be found in nature or made in a laboratory. All elements are listed on the Periodic Table of Elements according to the number of protons in the nucleus. The smallest part of an element is called the atom.</p><p>A compound is a form of matter that is made when two or more elements combine to form a chemical bond. The atoms become linked and can only be separated by a chemical reaction. Millions of compounds can be made from combinations of elements. Some common examples of compounds include salt, water, sugar, baking soda and vinegar. A molecule is the smallest part of a compound. Inside a salt shaker, there are millions of molecules of salt. </p><p>A compound is usually much different from the elements that make it up. For example, salt is a compound formed when sodium and chlorine chemically combine. Sodium is a gray solid that will catch on fire when placed in water. Chlorine is a greenish gas with a strong odor. However salt does not react with water and has no odor. The reason for this is when the atoms are chemically linked, they lose their original properties.</p><p>A chemical symbol is the abbreviation used to represent an element. A chemical formula is the abbreviation used to represent a compound. It is made up of symbols of the elements and the number of atoms of each element that are in the compound. </p><p>The chemical formula for water is H2O. The 2 after the H means there are two atoms of hydrogen. When there is no number written after a chemical symbol, there is one atom of that element. So in a water molecule, there are 2 atoms of hydrogen and 1 atom of oxygen. Another example of a compound is propane with a formula of C3H8, this means there are three carbon atoms and eight hydrogen atoms.</p><p>1. Define element: ______</p><p>2. Define compound: ______</p><p>3. Define molecule: ______</p><p>4. Give 2 examples of compounds ______</p><p>5. Describe what happens to an element’s properties when it joins with other elements to form a compound. 6. What is the difference between a chemical symbol and a chemical formula?</p><p>7. The formula for baking soda is NaHCO3. List the elements and the number of atoms of each element found in baking soda.</p><p>Element Name # of atoms Na - H - C - O - </p><p>8. Listed below are some compounds with their chemical formulas. For each formula, list the components of each compound.</p><p>Chalk CaCO3 Calcium – 1, Carbon – 1, Oxygen – 3</p><p>Salt NaCl ______</p><p>Sulfuric Acid H2SO4 ______</p><p>Sand SiO2 ______</p><p>Sugar C6H12O6 ______</p><p>Rust Fe2O3 ______</p><p>Hydrogen peroxide H2O2 ______</p><p>Aspirin C9H8O4______</p><p>Iron Pyrite (Fool’s Gold) FeS2______</p><p>9. Why is a chemical formula useful for scientists?</p><p>10. If salt is made of sodium and chlorine and chlorine is what they use to kill germs in a pool, why does salt not kill germs?</p>