Composition of Matter Chapter 2 The students will learn about the: difference between elements and compounds, types of mixtures and to distinguish between physical and chemical changes and properties

What is Matter? The “stuff” of which the universe is composed. It has mass and it occupies space. All matter is composed of atoms. –About 100 different types of atoms.

Types of Matter Solid –Matter that has a definite shape and volume. Not compressible. Liquid –Matter that has a definite volume and takes the shape of its container. Not compressible. Gas or Vapor –Matter that assumes both the shape and volume of the container. Readily compressible.

What is Mass? What is a substance? It is the amount of matter that an object contains. A substance is matter that has a uniform and definite composition. –Example: Hydrogen Oxygen Water Sugar Salt

Types of Substances Difference between Elements and compounds Elements –Substances that have only one type of atom. –It cannot be decomposed into simpler substances by chemical or physical means. –C, H, O, N, Na, Fe, Cu, K Compounds –A substance that has more than one type of atoms. –It can be broken down into elements only by chemical processes. –NaCl, H 2 O, C 6 H 12 O 6, H 2 SO 4

Compounds can be broken down into elements by chemical reactions. Example –H 2 SO 4 can be broken down into the following elements: H = Hydrogen S = Sulfur O = Oxygen

Difference Between Physical and Chemical change. Physical Change –A change in the form of substance, not in its chemical nature. –Chemical bonds are not broken nor formed in a physical change. –From ice to water to steam Chemical Change –The change of substances into other substances through a reorganization of the atoms; a chemical reaction. –2 H 2 + O 2  2 H 2 O

Difference Between Physical and Chemical Properties. Physical Properties –A quality or condition of a substance that can be observed or measured without changing the substance’s composition. –Example of physical properties are boiling point, density, color, volume, odor, and melting point.

Difference Between Physical and Chemical Properties. Chemical Properties –The ability of a pure substance to form new substances. –Examples of chemical properties are the ability to release heat or absorb heat, etc.

Indication of a Chemical Reaction 1.Production of Heat and Light. –Exothermic reaction: process that releases heat. –Endothermic reaction: Process that absorbs heat from its surroundings 2.Production of gas (bubbles). 3.Formation of a precipitate –A precipitate is a solid that separate from a solution. 4.Change in color.

Mixtures –It is a physical blend of two or more substances. –Something that has variable composition. –It can be separated by physical means. –Examples: sterling silver air soda coffee

Types of Mixtures solution 1.Heterogeneous Mixture –A mixture that is not uniform in composition. Salad Vinegar and oil 2.Homogeneous Mixture –Also known as Solution –A mixture that is uniform in composition. Salt water Water and food coloring

Distillation It is a purification process in which a liquid is evaporated and then condensed again to a liquid; used to separate dissolved solids from liquids or liquids from liquids according to boiling point.

Types of Matter (summary) MATTER SubstanceMixture ElementCompound Pure Not Pure HomogeneousHeterogeneous K, P, O Cu, Na NaCl, H 2 O C 6 H 12 O 6 Also Known as a Solution Alloys, suspensions, etc. Physically separable

Chemical Reactions Chemical reaction Reactants Products In a chemical reaction, one or more substances change into new substances. In chemical reactions, the starting substances are called reactants and the substances formed are called products.

Chemical Equation Reactants Yields Products CH O 2 CO H 2 O

Vocabulary Law of conservation of mass During a chemical reaction, the quantity of matter is unchanged. Mass of reactants = Mass of products This is the law of conservation of mass –In any physical or chemical change, Mass is not created nor destroyed; it is conserved.