matter – classifications, properties and changes 1

Matter – Classifications, Properties and Changes

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Universe ClassifiedMatter, the stuff of which the universe is

composed is the part of the universe that has mass and volume (occupies space)

Matter can be classified by noticing the similarities and differences in the characteristics of the substances under observation and then grouping them in various manners.

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Figure 3.1: Liquid water takes the shape of its container.

Figure 3.2: The three states of water.

States of Mattersolid, liquid, gas

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Properties of MatterProperties can be either

directly observable or inferred from the manner in which one piece of

matter interacts with an other piece of matter in the universe

Physical Properties are the characteristics of matter that can be observed without changing its composition Characteristics that are directly observable.

Chemical Properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy. Characteristics that describe the behavior of matter.

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Classify Each of the following as Physical or Chemical Properties

The boiling point of ethyl alcohol is 78°C.

Diamond is very hard.

Sugar ferments to form ethyl alcohol.

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Changes in MatterPhysical Changes are changes to matter

that do not result in a change in the fundamental components that make that substanceState Changes – boiling, condensing, melting,

freezing, subliming, depositing

Chemical Changes involve a change in the fundamental components of the substanceProduce a new substanceChemical reaction (reacts, burns =combusts,

tarnishes, rusts, ferments, rots, degrades)Reactants Products

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Gallium metal has such a low melting point (30°C) that it melts from the heat of a hand.

Oxygencombines with thechemicalsin wood toproduceflames.

Is a physical or chemicalchange taking place?Source: Jim Pickerell/Stone/Getty Images

Figure 3.3:Electrolysis,the decompositionof water by an electriccurrent, is achemicalprocess.

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Classify Each of the following as Physical or Chemical Changes

Iron is melted.

Iron combines with oxygen to form rust.

Sugar ferments to form ethyl alcohol.

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Elements and CompoundsPure Substances which cannot be broken

down into simpler substances by chemical reactions are elements

Most pure substances are chemical combinations of elements. These are compounds.Compounds are made up of elementsCompounds can be broken down into elementsProperties of a compound are not related to the

properties of the elements that compose itSame chemical composition at all timesCompounds are NOT found on the periodic table!

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Classification of Matter

Homogeneous = uniform throughout, appears to be one thing pure substances (elements and compounds) solutions (usually liquid phase, always homogeneous mixtures)

alloys (solid phase homogenous mixtures)

Heterogeneous = non-uniform, contains regions with different properties than other regions one phase usually solid

ALL PURE SUBSTANCES ARE HOMOGENEOUS

Mixtures may be Homogeneous or Heterogeneous15

Figure 3.4: When table salt is stirred into water (left), a homogeneous mixture called a solution

forms.

Figure 3.5: Sand and water do not mix to form a uniform mixture. After the mixture is stirred, the sand settles back to the bottom.

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Pure Substances vs. Mixtures Pure Substances

All samples have the same physical and chemical properties Constant Composition - all samples have the same

composition Homogeneous - same phase throughout Separate into components based on chemical properties

Mixtures Different samples may show different properties Variable composition (e.g. 3% hydrogen peroxide solution,

30% hydrogen peroxide solution) Homogeneous or Heterogeneous Separate into components based on physical properties

All mixtures are made of pure substances

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Alloys Homogeneous Mixtures

Steel (a mixture of iron and carbon)

Stainless Steel (iron, nickel, chromium)

Brass (copper and zinc)

Bronze (copper and tin)

Nichrome - (Nickel and chromium)

< 24K Gold and colored Golds

Sterling Silver (92.5% Ag rest usually Cu)

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Identity Each of the following as: a Pure Substance, a Homogeneous Mixture or a Heterogeneous Mixture

Gasoline

A river with gravel on the bottom

Copper metal

Steel

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Separation of MixturesMixtures are separated based on the different

physical properties of the componentsPhysical change

21EvaporationVolatility

ChromatographyAdherence to a Surface

FiltrationState of Matter (solid/liquid/gas)

DistillationBoiling Point

TechniqueDifferent Physical Property

Figure 3.6: Distillation of a solution consisting

of salt dissolved in water.

Figure 3.10: Theorganization of matter.