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# 7H Atoms, Elements and Molecules ## 1. The Air We Breathe * **Particles:** Tiny pieces of matter that make up everything. * **Atoms:** The simplest particles of matter that make up everything. * **Elements:** A substance made up of one type of atom. ## 2. Earth's Elements * **Earth's Crust:**...

# 7H Atoms, Elements and Molecules ## 1. The Air We Breathe * **Particles:** Tiny pieces of matter that make up everything. * **Atoms:** The simplest particles of matter that make up everything. * **Elements:** A substance made up of one type of atom. ## 2. Earth's Elements * **Earth's Crust:** Made up of oxygen, iron, silicon, aluminum, calcium and other elements. * **Naturally Occurring Elements:** Usually found as compounds, some found pure. Can be extracted from compounds by simple chemical reactions. * **Properties:** What an element is like, its appearance and how it behaves. * **Recycling:** Using a material again to save resources and make sure we don't run out. ## 3. Metals and Non-Metals * **Metals:** Solid, high melting point, strong, flexible, malleable, shiny, and good conductors of heat and electricity. Three-quarters of all elements are metals, found on the left side of the periodic table. * **Common Metal Properties:** Solid, high melting point, strong, flexible, malleable, shiny, good conductors of heat and electricity. * **Non-Metals:** Low melting points, brittle, not shiny and poor conductors of heat and electricity. **Examples include** * **Malleable:** Able to be beaten and bent into shape. * **Flexible:** Able to bend without breaking. * **Conductor:** A substance that allows something to pass through it (e.g. heat, electricity). * **Brittle:** Not easily bent – breaks under pressure. * **Magnetic:** Iron, nickel and cobalt are the only magnetic elements. ## 4. Making Compounds * **Mercury:** The only metal that is liquid at room temperature. * **Common Compound:** Silicon Dioxide is the most common compound in the Earth's crust, found in sand, quartz, and granite. * **Forming Compounds:** The first stage often involves heating a mixture of elements. Energy is often given out when elements react to form compounds. * **Compound formation examples:** * **Iron Sulfide:** Compound formed by heating a mixture of iron and sulfur. * **Properties of Iron Sulfide:** Iron can be separated from sulfur using a magnet but iron sulfide is not magnetic. * **Metal Ores:** A rock containing a compound of a metal. If one of the elements in the compound is a metal its name goes first. The non-metal at the end of the compound's name has its name changed so it ends in -ide. ## 5. Chemical Reactions * **Chemical Reaction:** A change in which one or more new substance is formed. * **Word Equation:** Used to model chemical reactions. * **Reactants:** The starting substances – written on the left of word equation. * **Products:** The new substances made – written on the right of word equation. ## Other Concepts * **Molecules:** Two or more atoms joined together in a group. * **Compounds:** Two or more different atoms joined together. * **Mixture:** Two or more substances jumbled together but not chemically joined together. * **Periodic Table:** A table that lists all of the known elements. * **Air:** A mixture of different gases – nitrogen, oxygen, argon, carbon dioxide. * **Pure:** A substance made up of a single element/compound and nothing else. * **Chemical Symbols:** The 1 or 2 letters given to each element. ## Thermal Decomposition * **Thermal Decomposition:** Using heat to break down a compound- used to extract metals from their compounds. * **Examples of Thermal Decomposition** * **Mercury Oxide:** Mercury oxide → mercury + oxygen (compounds containing a metal, carbon and oxygen. Found in limestone, chalk and marble) * **Calcium Carbonate:** Copper carbonate → copper oxide + carbon dioxide(Carbon dioxide turns limewater cloudy) * **General Rule:** A compound that contains two elements plus oxygen will end in -ate (e.g. zinc sulfate contains zinc, sulfur and oxygen). **Additional Notes:** The document also includes instructions to work through memorization and highlight definitions to aid in learning.