Classification of Matter This well-known molecule is a compound because it contains more than one element. A molecule but not a compound Ozone, O 3, is not a compound because it contains only a single element. Ordinary solid salt is a compound but not a molecule. It is built from interpenetrating lattices of sodium and chloride ions that extend indefinitely.

MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement MIXTUREPURE SUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes ColloidsSuspensions Courtesy Christy Johannesson

Elements only one kind of atom; atoms are bonded if the element is diatomic or polyatomic Compounds two or more kinds of atoms that are bonded substance with definite makeup and properties Mixtures two or more substances that are physically mixed two or more kinds of and Both elements and compounds have a definite makeup and definite properties. Packard, Jacobs, Marshall, Chemistry Pearson AGS Globe, page (Figure 2.4.1)

Matter Flowchart Examples: –graphite –pepper –sugar (sucrose) –paint –soda Courtesy Christy Johannesson element hetero. mixture compound solution homo. mixture hetero. mixture

Pure Substances Element –composed of identical atoms –examples: copper wire, aluminum foil Courtesy Christy Johannesson

Pure Substances Compound –composed of 2 or more elements in a fixed ratio –properties differ from those of individual elements –EX: table salt (NaCl) Courtesy Christy Johannesson

Pure Substances Law of Definite Composition –A given compound always contains the same, fixed ratio of elements. Law of Multiple Proportions –Elements can combine in different ratios to form different compounds. Courtesy Christy Johannesson

Pure Substances For example… Two different compounds, each has a definite composition. Carbon, C Oxygen, O Carbon monoxide, CO Carbon, C Oxygen, O Oxygen, O Carbon dioxide, CO 2 Courtesy Christy Johannesson

Mixtures Variable combination of two or more pure substances. HeterogeneousHomogeneous Courtesy Christy Johannesson

Mixtures Solution –homogeneous –very small particles –no Tyndall effect Tyndall Effect –particles don’t settle –EX: rubbing alcohol Courtesy Christy Johannesson

Mixtures Colloid –heterogeneous –medium-sized particles –Tyndall effect –particles don’t settle –EX: milk Courtesy Christy Johannesson

Mixtures Suspension –heterogeneous –large particles –Tyndall effect –particles settle –EX: fresh-squeezed lemonade Courtesy Christy Johannesson

Mixtures Examples: –mayonnaise –muddy water –fog –saltwater –Italian salad dressing Courtesy Christy Johannesson colloid suspension colloid solution suspension

Classification of Matter Materials Homogeneous Heterogeneous mixture Homogeneous mixture Substance ElementCompoundSolutionMixture Specific / General Order / Disorder Smoot, Smith, Price, Chemistry A Modern Course, 1990, page 43

Classification of Matter MATTER (gas. Liquid, solid, plasma) PURE SUBSTANCES MIXTURES HETEROGENEOUS MIXTURE HOMOGENEOUS MIXTURES ELEMENTSCOMPOUNDS Separated by physical means into Separated by chemical means into Kotz & Treichel, Chemistry & Chemical Reactivity, 3 rd Edition, 1996, page 31

Classification of Matter uniform properties? fixed composition? chemically decomposable? no yes hetero- geneous mixture solution element compound

Elements, Compounds, and Mixtures (a) an element (hydrogen) (b) a compound (water) (c) a mixture (hydrogen and oxygen) (d) a mixture (hydrogen and oxygen) Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 68 hydrogen atoms hydrogen atoms oxygen atoms

Elements, Compounds, and Mixtures (a) an element (hydrogen) (b) a compound (water) (c) a mixture (hydrogen and oxygen) (d) a mixture (hydrogen and oxygen) Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 68 hydrogen atoms hydrogen atoms oxygen atoms

Mixture vs. Compound Mixture Fixed Composition Bonds between components Can ONLY be separated by chemical means Variable Composition No bonds between components Can be separated by physical means Alike Different Contain two or more elements Can be separated into elements Involve substances Compound Different Topic

Compounds vs. Mixtures Compounds have properties that are uniquely different from the elements from which they are made. –A formula can always be written for a compound –e.g. NaCl  Na + Cl 2 Mixtures retain their individual properties. –e.g. Salt water is salty and wet