Chapter 5 State Standards: 3.b; 5.a; 7.c 1

Chapter 5-1: Elements 2

Elements An element is made up of only one type of atom (particle) It is a pure substance that cannot be separated into simpler substances A pure substance is when all the atoms (building blocks) are identical within the substance 3

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Classifying Elements Elements are classified according to their characteristic properties (physical & chemical) Physical: hardness, melting point, density, thermal conductivity, color, etc. Chemical: reactivity and flammability 5

Grouping Elements 3 Major Groups: Metals: shiny, conduct heat and electrical current Nonmetals: do not conduct heat or electric current, solid nonmetals are dull in appearance Metalloids: have properties of both metals and nonmetals 6

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Chapter 5-2: Compounds 8

Compounds Compounds are made by chemically combining two or more elements Chemically combine to form a new substance with different properties 9 Proteins are found in all living things

Properties of Compounds Compounds have their own unique physical and chemical properties Physical: melting point, density, and color Chemical: reactivity Combine in specific ratios 10

Breaking Down Compounds Since compounds can only be formed chemically, they can only be broken down through a chemical change Usually requires energy in the form of heat or electrical current 11

Common Compounds Vinegar (acetic acid) Baking Soda (sodium bicarbonate) Table Salt (sodium chloride) Carbonated Water (carbonic acid) Citric Acid 12 NaHCO 3 NaCl CH 3 COOH H 2 CO 3 C6H8O7C6H8O7

Chapter 5-3: Mixtures 13

Mixtures Combination of two or more substances that are not chemically combined Materials do not react to form a compound Elements in a mixture keep their original properties (characteristic properties) 14

Physically Separating Mixtures Using a magnet Centrifuge – separates mixtures based on densities Filtering Evaporating – heating p143 15

Solution Solution is a homogeneous (evenly mixed) mixture containing two or more substances A simple solution is two substances that are going to be combined. Solute - the substance to be dissolved Soluble – able to dissolve Insoluble – unable to dissolve Solvent - the one doing the dissolving *substance with largest amount is solvent Can be gases, liquids or solids 16

Concentration of Solutions The amount of a dissolved substance in a volume of mixture/solution (g/mL) Solubility – how well a solute can dissolve in a solvent 17 Same amount of solute, different amount of solvent. Same amount of solvent, different amount of solute. Concentrated Diluted

Examples of Solutions StatesExamples Gas in gasAir (oxygen in nitrogen) Gas in liquidSoft drinks (carbon dioxide in water) Liquid in liquidAntifreeze (alcohol in water) Solid in liquidSalt water (salt in water) Solid in solidBrass (zinc in copper) 18 Ex: Sugar in water vs. Sand in water. Sugar dissolves and is spread throughout the glass of water. The sand sinks to the bottom. The sugar-water could be considered a solution. The sand-water is a mixture.

Elements Compounds Chemically Combined Elements change Mixtures Elements stay the same 19