matter and change mrs. mcguire chemistry. a) classification of matter some criteria for the...

Matter and Change

Mrs. McGuire

Chemistry

A) Classification of MatterSome Criteria for the Classification of Matter Properties

State (solid, liquid, gas)

Composition

Properties

Intensive

-Do not depend on amount of matter.Ex: color, odor, luster and conductivity

Extensive

-Depend on amount of matter.Ex: mass, length, and volume

Intensive and Extensive Properties

Sulfur

Properties

Physical: observed without changing the composition of the substance.

Chemical: the ability of a substance to undergo a specific chemical change

REGENTS QUESTION

Which statement describes a chemical property of sodium?

(1) Sodium has a melting point of 371 K.

(2) Sodium has a molar mass of 23 grams.

(3) Sodium can conduct electricity in the

liquid phase.

(4) Sodium can combine with chlorine to

produce a salt

Examples of Physical PropertiesColor, odor, hardness, density,

melting point, boiling point, state, solubility.

Substance State Color Melting

Point (C°)

Boiling Point (C°)

Density (g/cm3)

Oxygen O2 Gas Colorless -218 -183 0.0014

Mercury Hg Liquid Silvery-white

-39 357 13.5

Bromine Br2 Liquid Red-brown -7 59 3.12

Water H2O Liquid Colorless 0 100 1.00

Sodium Chloride

NaCl Solid White 801 1413 2.17

Example: Physical Properties

States of Matter

Solid fixed shape and volume,

incompressibleLiquid

fixed volume, takes the shape of its container

Gastakes the volume and shape of

its container

STATES of matter

Bromine

Gas (Vapor)

Liquid

Change of Phase

Condensation gas liquidFreezing liquid solidDeposition gas solid

Melting solid liquidEvaporation liquid gasSublimation solid gas

Boiling: Evaporation occurring beneath the liquid’s surface.

BONUS REGENTS QUESTION

Which physical change is endothermic?

(1) CO2(s) → CO2(g)

(2) CO2(g) → CO2(ℓ)

(3) CO2(ℓ) → CO2(s)

(4) CO2(g) → CO2(s)

Chemical Properties and Chemical Changes

Is changing phase a physical or chemical change? ___________________Explain:

H2O composition is fixed- compound

Gaseous Phase Liquid Phase

REGENTS QUESTION

Coal is a fuel consisting primarily of carbon. In an open system, the carbon that burns completely in air produces carbon dioxide and heat. This reaction is represented by the balanced equation below.

C(s) + O2(g) → CO2(g)+ heat

Draw at least five particles to represent the phase of the product.

Chemical Properties

The ability of a substance to transform into a new substance (to undergo a chemical change).

Example: Magnesium reacts with oxygen to form magnesium

oxide.

Magnesium Mg

Burning of Magnesium2Mg+ O2 2MgO

REGENTS QUESTION

Which term identifies a type of chemical reaction?

(1) decomposition

(2) sublimation

(3) Distillation

(4) vaporization

Physical ChangesPhysical change: a change in the

physical properties of a substance.

Composition does not change.

May be reversible or irreversible.Examples:

Reversible: Liquid water < -- > solid water

Irreversible: Tearing a piece of paper

Chemical Change

A change that produces matter with a different composition than the original matter.

Atoms rearrange themselves into new combinations.

Burning of MethaneCH4 +2O2 CO2 + 2H2O

Burning of MethaneCH4 + 2O2 CO2 + 2H2O

Recognizing a Chemical Change

energy exchange production of a gascolor changeformation of a precipitate

Formation of a Precipitate

Cu(OH)2

Precipitate

The Law of Conservation of Mass (Antoine Lavoisier)

In any chemical or physical change, mass is neither created or destroyed

Mass is CONSTANT

Classification of Matter(by composition)

(Pure) Substance

Matter that has a uniform and definite composition.Elements: organized on a

periodic table, unique name, one, two or three letter symbol

Compounds: two or more elements combined chemically

REGENTS QUESTION

All atoms of uranium have the same

(1) mass number

(2) atomic number

(3) number of neutrons plus protons

(4) number of neutrons plus electrons

REGENTS QUESTION

Which substance can not be broken down by a chemical change?

(1) ethane

(2) silicon

(3) Propanone

(4) water

c) Elements and Compounds

Pure substances

Elements can NOT be decomposed by chemical means, but compounds can.

ElementsThe simplest substances.Can not be separated into simpler

substances.Building blocks of all matter. More than 100 known elements.Represented by chemical

symbols.

Chemical Symbols of Elements

System started by Jons Berzelius (Sweden, 1779-1848)

One or two first letters of name of the element.

Many elements names have roots from: Latin, Greek, mythology, geography, names of scientists.

Examples:

Americium, Am

Einsteinium, Es

Bromine, Br

Helium, He

Lead(Plumbum), Pb

Niobium, Nb

Iron (Ferrum), Fe

Mendelevium, Md

CompoundA substance that contains two or more

elements chemically combined.

Compounds have different properties from the individual substances.

(Ex: H2O)

Example: H2O

The law of definite proportions states that a compound is always composed of the same elements in the same proportions.

Percent composition

Substance or mixture?

If composition is fixed and may not changesubstance

REGENTS QUESTION

Which sample of matter is a mixture?

(1) Br2(ℓ)

(2) KBr(s)

(3) K(s)

(4) KBr(aq)

Mixture: a physical blend of two or more substances that are not chemically combined.

Homogeneous:

Uniform composition and properties throughout

Heterogeneous two or more sustances are physically combined and retain their original properties

MixturesA physical blend of two or more

substances.

Mixtures

Homogeneous

Heterogeneous

Example: Stainless Steel

A homogeneous mixture of:

-Iron (Fe)

-Chromium (Cr)

-Nickel (Ni)

Heterogeneous Mixtures

Non-uniform composition throughout the mixture

Two or more phases.

Example:

Oil and vinegar

Example: Gaseous MixtureElements argon and nitrogen and

a compound (water vapor). Choice ?

Note:

Mixtures can be physically separated.

Mixtures exhibit physical properties similar to the components of the mixture.

Separation Methods

Use differences in the physical properties of the components of the mixture.

Example: Separate iron filings from sulfur using a magnet.

Filtration: separates a solid from a liquid in a heterogeneous mixture

Distillation: -separate dissolved solids from a liquid -uses boiling and condensation.

Distillation of Crude Oil (Refining)

Crude Oil is a mixture of Hydrocarbons

BONUS REGENTS QUESTION

Which formula represents a hydrocarbon?

(1) CH3I

(2) CH3CH3

(3) CH3NH2

(4) CH3OH

Distillation of Crude Oil

REGENTS QUESTION A mixture consists of sand and an aqueous

salt solution. Which procedure can be used to separate the sand, salt, and water from each other?

(1) Evaporate the water, then filter out the salt. (2) Evaporate the water, then filter out the sand.

(3) Filter out the salt, then evaporate the water. (4) Filter out the sand, then evaporate the water.