Upload
alison-melton
View
222
Download
2
Tags:
Embed Size (px)
Citation preview
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