Classification of Matter - Mrs....

CLASSIFICATION OF MATTER Qualitative/Quantitative, Extensive/Intensive, States of Matter, Physical/Chemical Properties, Elements, Compounds, Homogeneous and Heterogeneous Mixtures

What is Chemistry? Chemistry is the study of matter, its composition, properties, and

transformations.

What is Matter? Matter is stuff!

Matter is anything that has mass and volume.

Mass is the amount of material in an object.

Volume is the amount of space the object occupies.

Naturally occurring: • cotton • sand • digoxin, a cardiac drug

Synthetic (human-made): • nylon • Styrofoam • ibuprofen

States of Matter • Matter is anything that has mass and occupies

space. • A solid is a substance with a fixed volume and

shape. • A liquid is a fluid that has fixed volume but not

a fixed shape. •  The shape of a liquid is dictated by the

shape of the container. • A gas has no fixed volume or shape.

•  The gas in a balloon adopts the shape of the balloon.

Solids Liquids Gases particles that are

close together in a fixed arrangement

particles that are close together but

mobile

particles that are far apart

definite volume

definite volume an indefinite volume (same volume as

container) Maintains shape

indefinite shape (same shape as

container)

indefinite shape (same shape as

container) particles that move

very slowly particles that move

slowly particles that move

very fast

Gases are compressible when we apply a force

Gases are compressible because there is so much empty space

between gas particles.

Applying a force pushes the particles into the

empty space, compressing the gas.

Liquids are not very compressible because there is little empty space between particles.

Identify Each as a Solid, Liquid, or Gas •  It has a definite volume but takes the shape of the

container.

•  Its particles are moving very quickly.

•  It fills the volume of the container.

•  It has particles in a fixed arrangement.

•  It has particles that are close together and are mobile.

• No change in volume when placed in a different container.

• Very low density

• Compressible

•  Liquid

• Gas

• Gas

• Solid

•  Liquid

• Solid or liquid

• Gas

•  gas

Properties – Words that describe matter (adjectives) • Physical properties – can be observed or measured

without changing the composition of the material.

• Chemical properties – determine how a substance can be converted into another substance.

Boiling point Color Melting point Odor Solubility State of matter

Toxicity Flammability Chemical stability Biological activity

Quantitative versus Qualitative Properties Quantitative property

• A property that is described in terms of a number (with units)

•  Involves a measurement

• Mass • Volume •  Temperature • Melting point • Boiling point

Qualitative Property

• A property that is described in terms of appearance.

• Color • Odor •  Taste

Intensive Versus Extensive Properties Intensive properties

•  do NOT depend on the amount of substance.

• Density •  Temperature • Boiling point •  color

Extensive properties • DEPEND on the amount of

substance.

• Mass •  volume

Classify the Physical Properties of Copper

Qualitative or Quantitative? Intensive or Extensive?

Density and Magnetism are Physical Properties

Classify as a Physical or Chemical property

• Melting point • Density • Magnetic • Tarnishes in air • Gas burns in air. • Gas has a pungent odor.

• Physical • Physical • Physical • Chemical • Chemical • Physical

Classify as a Physical or Chemical property

• Iron and oxygen form rust. • Iron is more dense than aluminum. • Magnesium burns brightly when ignited. • Oil and water do not mix. • Mercury melts at -39°C.

Heat Conduction by Diamond: Physical or Chemical Property?

• Physical change – alters the material without changing its composition (change of state, appearance, shape)

• Chemical changes – the chemical reaction that converts one substance into another.

Physical and Chemical Changes

Examples of Physical Change: Changes of State

Sublimation is an example of Physical change

• Sublimation is the physical change from a solid directly to a gas.

• Sublimation is typical of dry ice, which sublimes at -78°C.

Physical Changes can be Dramatic!

Chemical Changes: When one or more substances are changed into new substances.

• Reactants – • stuff you start with

• Products – • the NEW stuff you make

• NEW PROPERTIES • Not easily reversed

Iron Fe

Iron (III) oxide Fe2O3

Signs of a Chemical Change

change in color or odor

formation of a gas

formation of a precipitate (solid)

change in light or heat

Classify Each of the Following as a Physical or Chemical Change

• Burning a candle •  Ice melting on the street •  Toasting a marshmallow • Cutting a pizza • Polishing a silver bowl • Rusting iron • Dissolving in water • Grinding spices • Crushing an Al can

• Chemical • Physical • Chemical • Physical • Chemical • Chemical • Physical • Physical • Physical

All matter can be classified as either a Pure Substance or a Mixture

•  A pure substance is composed of only a single component (atom or molecule).

•  A mixture is composed of more than one component.

A Pure Substance is classified as an Element or a Compound

• A Pure substance •  Is composed only a single component •  Has a constant composition •  Cannot be broken down to other pure substances by a physical change

•  Is an element when composed of one type of atom •  simplest kind of matter • Cannot be broken down by a chemical change

Is a compound when composed of two or more elements chemically combined in a definite ratio (H2O)

• Can be broken down by a chemical change • When broken down, the pieces have completely different

properties than the compound.

Elements are Pure Substances that Contain Only One Type of Atom

• Examples: • Copper (Cu) • aluminum foil (Al)

Elements have abbreviations called Element Symbols

• Element symbols consist of one or two letters. • The 1st letter of an element symbol is always capitalized and the 2nd letter, if present, is never capitalized. •  H and Al • Na, Au, Sn, Ag, Cu

• You will need to memorize the symbols of the first 40 elements.

Compounds are Pure Substances Formed by Chemically Joining Two or More Elements

Compounds are Different from Their Elements

Elements and Compounds are Pure Substances

Mixtures • A mixture is matter that consists of two or more substances

that are physically mixed, not chemically combined • A mixture can be separated by physical means into its

components without changing the identities of the components.

Mixtures can be formed from solids, liquids, and gases

Classification of Matter

Mixtures – Homogeneous Versus Heterogeneous

In a homogeneous mixture, § uniform composition throughout § the different parts of the mixture are not

visible

In a heterogeneous mixture, § the composition is not uniform; it varies

from one part of the mixture to another § different parts of the mixture are visible

All Solutions are Homogeneous Mixtures

• Solutions are mixed molecule by molecule • Every part of a solution keeps the properties of the components

• Solutions can occur between any state of matter • Solid and liquid – Kool aid • Liquid and liquid – anti-freeze • Gas in gas – air • Solid in solid – brass • Liquid in gas – water vapor

Homogeneous Mixtures are aka Solutions

• very small particles • no Tyndall effect

Tyndall Effect

w particles don’t settle w Example: rubbing alcohol w Can be separated by physical

means, though not easy to separate

Colloids and Suspensions are Heterogeneous Mixtures

• Colloid •  medium-sized particles •  Tyndall effect •  particles don’t settle •  Example: milk

• Suspension •  large particles •  Tyndall effect •  particles settle •  Example: fresh-squeezed lemonade

Homogeneous or Heterogeneous

Mixture?

To tell whether a substance is a pure substance or a mixture, determine whether it can be physically separated into two or more pure substances.

MATTER

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture

Compound

Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

no yes Is the composition uniform?

no yes

Colloids Suspensions

Identify Each of the Following as an Element, Compound, Homogeneous Mixture, or

Heterogeneous Mixture

• Pasta and tomato sauce • Aluminum foil • Helium • Air • Graphite • Pepper • Sugar • Sugar water • Paint

• Heterogeneous mixture • Element • Element • Homogeneous mixture • Element • Heterogeneous mixture • Compound • Homogeneous mixture • Heterogeneous mixture

Identify Each of the Following as a Solution, Colloid, or Suspension

• Mayonaise • Muddy water • Fog • Salt water • Italian Salad Dressing

• Colloid • Suspension • Colloid • Solution • Suspension

Separating mixtures by Physical Processes

(a) Filtration is a technique that uses a porous barrier to separate a solid from a liquid.

(b) Distillation separates liquids based on differences in their boiling points. (c-d) Separation of the components of ink using chromatography

Distillation is a process for separating liquids by their boiling points