Chapter 2 Matter and Change Chemistry pg. 38. 2.1 Properties of Matter Properties used to describe matter are classified as: 1. Extensive – depends on.

Chapter 2Matter and Change

Chemistry pg. 38

2.1 Properties of Matter

• Properties used to describe matter are classified as:1. Extensive – depends on the amount of

matter in a sample ex. Mass, volume

2. Intensive – depends on the type of matter in a sample, not the amount ex. Color, hardness, boiling point

Substance

• Matter that has a uniform and definite composition

ex. Gold, copper (pure substances)

Every sample has identical intensive properties because every sample has the same composition

Physical Property

• A quality or condition of a substance that can be observed or measured without changing the substance’s composition

• Help chemists identify substances• Hardness• Color• Conductivity• Malleability(see Table 2.1, Pg. 40)

Three states of matter

• Solid-definite shape, volume, not easily compressed

• Liquid-indefinite shape, flows, definite volume, almost incompressible

• Gas-indefinite shape, indefinite volume, easily compressed

• http://www.chem.purdue.edu/gchelp/liquids/character.html

Physical Changes

• Properties of a material change but the composition does not

ex. Boil, freeze, melt, condense AND break, split, grind, cut, crush

Physical changes can be REVERSIBLE or IRREVERSIBLE

Classifying Matter(2.2 and 2.3)

• Matter…has mass, takes up space

• Mixture…physical blend of two or more components–Based on distribution, can be

homogeneous or heterogeneous

Heterogeneous Matter• The composition is not uniform throughout• Considered a mixture because more than

one phase–Any region with a uniform set of

properties

Examples?

Homogeneous Matter• The composition is uniform throughout• One phase…components evenly distributed

Mixture (solution)

Substance

Solutions

• Homogeneous mixtures• Solute in a solvent (dissolves the

solute)• Many are liquids, but can be

gases or solids

Substances• Homogeneous matter, same composition

throughout

Elements Compounds -one kind of atom -2 or more

elements chemically joined -fixed proportions

Not sure, use the chart

Separating mixtures

• Distillation - a liquid is boiled to produce a vapor which is condensed into a liquid

Other ways?

distillation• How to perform simple distillation in the che

mistry lab | Wonder How To

2.3 Elements and Compounds

• Substances classified as 1. ____________- simplest form of matter

that has a unique set of properties (O, H) 2. ___________- substance that contains 2

or more elements chemically combined in a fixed proportion (C6H12O6)

• Compounds can be broken down by _____________ means.• Elements cannot be broken down

• Chemical change produces matter with a different composition than the original matter

Sugar Carbon + Water

Properties of Compounds• Generally, properties of compounds are

different from their component elements

• Sodium - soft, gray metal, reacts with oxygen +• Chlorine - yellow-green poisonous gas Sodium chloride Reaction

Distinguishing Substances and Mixtures

• If the composition of a material is fixed, the material is a substance

examples?

• If the composition of a material may vary, the material is a mixture

examples?

Classifying Matter

• Classify the following materials as an element, compound, or mixture.

a. Table salt

b. Salt water

c. Sodium

Symbols and Formulas

• Chemical symbols elements O, C, Na, Ne

• Chemical formulas compounds CO2 , H2O

2.4 Chemical Reactions

• Chemical Property – the ability of a substance to undergo a specific chemical change (describes the way a substance may react to form other substances)

examples?

- can be observed only when a substance undergoes a chemical change

• Fig. 2.13 (pg. 53)Chemical reaction S + Fe

*physical - composition of matter never changes*chemical – composition of matter always changesChemical change = chemical reaction

Reactants Products

• Chemical change = chemical reaction (one or more substances change into one or more new substances)

Reactants Products

Recognizing Chemical Changes

4 Ways:1. 2. 3.4.

• Precipitate an insoluble substance that

forms in, and separates from, a solution

Identify clues for chemical changes

magnesium ribbon in flame

Sodium iodide solution added to mercury(II) chloride solution

Law of Conservation of Mass

• In any physical change or chemical reaction, mass is ________________.

mass of products = mass of reactants