Matter- Properties and Change Chapter 3 Matter- Properties and Change

Properties of Matter Matter can be defined as anything occupying space that has mass A substance is matter that has a uniform and unchanging composition : Example: Table salt or Water are pure substances

States of Matter Solid: definite shape and volume, tightly packed, incompressible Liquid: flows, constant volume, takes shape of container Gas: molecules are far apart and freely moving

Physical vs. Chemical Changes Physical: difference appearance, same composition Boiling water, breaking a crystal Chemical: one or more substances that change to form a different substance Example: rust, fire *color change, heat, formation of a gas are all indicators that a chemical change has occurred

Conservation of Mass (matter) Mass of the reactants = Mass of Products “Matter cannot be created nor destroyed but changes from one form to another” Example: A 10.0 g sample of magnesium reacts with oxygen to form 16.6 g of magnesium oxide. How many grams of oxygen reacted?

Mixtures Heterogeneous mixture: substances remain individual Example: sand and water Homogeneous mixture: constant composition throughout = SOLUTIONS Example: ice tea * mixtures can be separated by physical means such as filtration, distillation, crystallization, and chromatography

Elements and Compounds Elements: cannot be broken down into simpiler substances by chemical or physical means Organized and predicted by periodic table- Mendeleev Compound: chemically combined two or more elements

Law of definite proportions The compound is always made up of the elements in the same proportion of mass Percent by mass(%) = mass of element X100 mass of compound Example: 500g of Sucrose was found to have 211.0 g of Carbon. What percent by mass is Sucrose composed of Carbon?

Law of Multiple Proportions Elements can form compounds in different ratios which are expressed in the chemical formula and can be calculated by percent mass. Example: H2O and H2O2