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 particles that move very slowly indefinite shape (same shape as container) particles that move slowly indefinite shape (same shape as container) 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. Liquid 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 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. Boiling point Melting point Solubility Color Odor State of matter Chemical properties determine how a substance can be converted into another substance. Toxicity Chemical stability Flammability Biological activity
Quantitative versus Qualitative Properties Quantitative property Qualitative Property A property that is described in terms of a number (with units) Involves a measurement Mass Volume Temperature Melting point Boiling point 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 and Chemical Changes 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.
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 Fe 2 O 3
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 A Pure substance Element or a Compound 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 (H 2 O) 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 1 st letter of an element symbol is always capitalized and the 2 nd 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 w particles don t settle Tyndall Effect 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 yes Can it be physically separated? no MIXTURE PURE SUBSTANCE yes Is the composition uniform? no yes Can it be chemically decomposed? no Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element 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