Mixtures, Elements, and Compounds PDF

Mixtures, elements and compounds Teacher: Ms. Pusey Follow up question of burning magnesium Introduce Magnesium (the Element): Hold up a piece of magnesium ribbon. Ask students: “What do you think this shiny, silvery material is made of?” Explain that magnesium is a metal...

Mixtures, elements and compounds Teacher: Ms. Pusey Follow up question of burning magnesium Introduce Magnesium (the Element): Hold up a piece of magnesium ribbon. Ask students: “What do you think this shiny, silvery material is made of?” Explain that magnesium is a metallic element (found on the periodic table) and is represented by the symbol Mg. Reinforce: Magnesium is a pure element because it is made of only one type of atom. Demonstration Burning the Magnesium: Light a Bunsen burner and, using tongs, hold the magnesium ribbon in the flame. Ask students: “What do you think will happen when we heat this element?” As the magnesium begins to burn, students will observe a very bright white light and a powdery white substance forming as it burns. Ask: “Why do you think it is glowing so brightly?” ThePhoto by PhotoAuthor is licensed under CCYYSA. Final stage of burning Magnesium ribbon Collect the White Ash: Once the magnesium has completely burned, a white powder (magnesium oxide) will be left behind. Place the white ash (magnesium oxide) on a heat-resistant surface (like a Petri dish or beaker). Ask students: “What do you think this white substance is? Is it still the same element we started with, or has it changed?” Leading discussion Magnesium Ribbon: An Element: Discussion: "The shiny ribbon we started with was magnesium, a pure element made up of only one type of atom — magnesium atoms." Emphasize that elements are the simplest form of matter and cannot be broken down into simpler substances by chemical reactions. The Reaction: Formation of a Compound: Explain: When the magnesium burned, it reacted with oxygen from the air. This is a chemical reaction where magnesium atoms combined with oxygen atoms to form a new substance: magnesium oxide (MgO). Cont'd Ask: “What do you think happens when atoms of different elements combine?” Lead to the explanation that when elements chemically bond, they form a compound. MgO is a compound because it contains two different elements, magnesium and oxygen, chemically bonded together. Molecules in Compounds: Explain: A molecule is formed when two or more atoms bond together. In this case, the compound magnesium oxide is made up of molecules, with each molecule containing one magnesium atom and one oxygen atom (MgO). Pure substance Pure substance is a type of matter that is made up of only one kind of particle that is chemically bonded. This Photo by Unknown author is licensed under CC BY. Elements An element is a pure substance made up of only one type of atom. It cannot be broken down into anything simpler by chemical means. Compounds A compound is a substance made when two or more different elements are chemically combined Examples of compounds include water and sodium chloride This Photo by Unknown author is licensed under CC Molecules A group of two or more than two atoms of the same or different elements that are chemically bonded together is called a molecule. For example, two atoms of hydrogen and one atom of oxygen react with each other and form one This Photo by Unknown author is licensed under CC BY-NC. molecule of water. Mixture A mixture is a combination of two or more substances that are physically combined and can be separated by physical means There are two types of mixtures Homogeneous Mixture Heterogenous Mixture Homogeneous Mixture A homogeneous mixture is a mixture throughout the solution in which the composition is uniform. This means that you cannot see the different particles that make up the mixture. This Photo by Unknown author is licensed under CC BY-ND. Heterogeneous Mixture a mixture in which the properties and composition are non-uniformed. Example salt and pepper, sand and water This Photo by Unknown author is licensed under CC Classification of mixtures A solution is a homogeneous mixture of one or more solutes dissolved in a solvent. solvent: the substance in which a solute dissolves to produce a homogeneous mixture. solute: the substance that dissolves in a solvent to produce a This Photo by Unknown author is licensed under CC BY-ND. homogeneous mixture.  Classification of mixtures A suspension is a heterogeneous mixture in which some of the particles settle out of the mixture upon standing. Example: muddy water, sand in water. A colloid is a heterogeneous mixture in which the dispersed particles are intermediate in size between those of a solution and a suspension. Examples include milk and oil and water. Summary of solution Solutions are transparent, meaning light can pass through them without being scattered. Example: Salt dissolved in water, sugar dissolved in tea. Key Characteristics: Homogeneous (uniform composition throughout). The solute particles do not settle over time. Cannot be separated by filtration. Examples: saltwater, vinegar, air (mixture of gases). ThePhoto by PhotoAuthor is licensed under CCYYSA. Summary of suspension Suspensions are opaque or cloudy, and the particles can scatter light. Example: Muddy water, sand in water, flour in water. Key Characteristics: Heterogeneous (non-uniform composition). The particles settle over time. Can be separated by filtration. Examples: muddy water, flour in water, salad ThePhoto by PhotoAuthor is licensed under dressing. CCYYSA. Summary on colloid Colloids appear homogeneous to the naked eye but are actually heterogeneous at a microscopic level. Example: Milk, mayonnaise, jelly, fog. Key Characteristics: The particles do not settle over time. Exhibits the Tyndall effect (scattering of light). Cannot be separated by ordinary filtration. Examples: milk, fog, whipped cream. ThePhoto by PhotoAuthor is licensed under CCYYSA. questions What is an element? Provide two examples. How are elements different from compounds? Why can’t elements be broken down into simpler substances? What is a compound? Provide two examples of compounds. questions How are the properties of a compound different from the properties of the elements that make it up? Explain how water (H₂O) is a compound. Which elements are present, and how do they combine? Why can’t compounds be separated by physical methods like mixtures? What is a mixture? Provide two examples of mixtures from everyday life. How do mixtures differ from compounds? What are the two main types of mixtures? Explain the difference between them with examples.