2.1 Properties of Matter Identify properties of matter as extensive or intensive. Define physical property and list several common physical properties of substances. Differentiate among three states of matter. Describe a physical change.

Properties of Matter Bamboo has properties that make it a good choice for use in chopsticks. It has no noticeable odor or taste. It is hard, yet easy to split, and it is heat resistant. You will learn how properties can be used to classify and identify matter.

Properties of Matter Properties:used to identify substances Extensive: depends on the amount of matter Intensive: depends on the nature of matter (NOT the amount)

Properties of Matter Physical Property observed or measured without changing the substance’s composition ex.: mass, color, density, melting point, boiling point, state, etc.

States of Matter  There are three states of matter:  solid: definite shape and definite volume, can not be compressed easily  liquid: no definite shape but definite volume, also difficult to compress  gas: no definite shape or volume, easily compressed  (vapor : gaseous state of a substance that is normally a solid or liquid)

Physical Changes do not involve a change in the identity of the substance Physical changes can be reversible or irreversible

Physical Changes As gallium melts in a person’s hand, the shape of the sample changes, but the composition of the material does not change.

–1.Which of the following would be described as an extensive property of matter? temperature color mass hardness 2.1 Section Quiz.

–2.Which properties can be observed without changing the composition of a substance? all properties of a substance intensive properties chemical properties physical properties

–3.Match the states of matter with the following descriptions: (1) takes the volume and shape of its container (2) has a definite shape and volume (3) has a definite volume but an indefinite shape (1) liquid, (2) solid and (3) gas (1) gas, (2) solid, and (3) liquid (1) gas, (2) liquid, and (3) solid

2.2 Mixtures Categorize a sample of matter as a substance or a mixture. Distinguish between homogeneous and heterogeneous samples of matter. Describe two ways that components of mixtures can be separated.

Mixtures mixtures: physical blend of two or more components with each component keeping its own properties the composition of a mixture is not definite throughout like a substance

Types of Mixtures Heterogeneous mixtures: composition is not uniform throughout Homogeneous mixtures: composition is uniform throughout (often called solutions) phase: part of a sample with uniform composition and properties

Separating Mixtures differences in physical properties can be used to separate mixtures filtration: separates solids from liquids in a heterogeneous mixture distillation: separates a liquid from solids and liquids in a homogeneous mixture

Solve

2.2 Section Quiz. –1. Which of the following phrases describes a mixture? composition varies composition may vary components cannot be separated

2.2 Section Quiz. –2. Which of the following is a homogeneous mixture? vinegar iron filings in sand chicken noodle soup muddy water

2.2 Section Quiz. –3. Which technique is used to separate homogeneous mixtures? filtration distillation magnetism dissolving

2.3 Elements and Compounds Explain the difference between an element and a compound. Distinguish between a substance and a mixture. Identify the chemical symbols of elements, and name elements, given their symbols.

Elements and Compounds element: simplest form of matter that has a unique set of properties compound: substance made of two or more different elements chemically bonded (not mixed) in a fixed proportion properties of compounds: are different from properties of the elements that make them up ex.: H 2 0

Substances If the composition of a material is fixed, the material is a substance. If the composition of a material may vary, the material is a mixture.

Chemical Change produces matter with a different composition than the original matter –one or more substances react to form new substance(s)

Symbols and Formulas chemical symbol: represents an element using a capital letter and sometimes a second lower case letter symbols come from the element names which are usually English but can be Latin or from some other source

Symbols and Formulas subscripts: indicate the number of atoms of an element in any compound chemical formula: represents the number and type of elements in a compound compounds have a fixed composition so there formula will always be the same

2.3 Section Quiz –1. Passing an electric current through a certain substance produces oxygen and sulfur. This substance cannot be a(n) compound. mixture. element. solution.

2.3 Section Quiz –2. Which of the following is a mixture? sodium chloride carbon dioxide sucrose air

2.3 Section Quiz. –3. The symbol for the element potassium is K. Po. P. Pt.

2.4 Chemical Reactions Describe what happens during a chemical change. Identify four possible clues that a chemical change has taken place. Apply the law of conservation of mass to chemical reactions.

Chemical Reactions chemical property: ability of a substance to undergo a specific chemical change chemical changes are also referred to as chemical reactions reactants form products

Indications of Chemical Change all of these indicate a possible chemical change but may not mean one has actually occurred energy transfer –observed as heat absorbed or given off and/or light being given off color change gas production –observed as bubbles being given off formation of a precipitateprecipitate –observed as a solid settling out of a liquid

Law of Conservation of Mass Mass is neither created nor destroyed. In a chemical reaction, the mass of the reactants equals the mass of the products