Elements, Compounds & Mixtures

Elements The simplest form of matter  Simple substance  One kind of atoms  Represented by -One or two letter symbol  Building blocks for all other substances  Can not be broken down and composed of constituent atoms

Compounds Made up of two or more elements chemically combined Represented by chemical formulasRepresented by chemical formulas Sodium + chlorine  sodium chloride NaClSodium + chlorine  sodium chloride NaCl H 2 O  H 2 + O 2 Always present in the same ratio in a compoundAlways present in the same ratio in a compound Can be Chemically separatedCan be Chemically separated

MIXTURES Two or more substances physically combined do not combine in same ratios can be separated by physical meanscan be separated by physical means constituent substances retain their original propertiesconstituent substances retain their original properties (salt & water - salt water)(salt & water - salt water)

MIXTURESHomogeneous uniform compositionuniform composition called “solutions”called “solutions” Salt water, alloys, etc.Salt water, alloys, etc. consist of a single phaseconsist of a single phase Alloy – mixture of two or more metalsAlloy – mixture of two or more metalsHeterogeneous Not uniformNot uniform Sand and salt, oil and vinegar, etc.Sand and salt, oil and vinegar, etc. consists of two or more phasesconsists of two or more phases Any part of a system with uniform composition and properties is called a phase.

Separating Mixtures Separation by physical meansSeparation by physical means Uses differences in physical properties to separateUses differences in physical properties to separate Rocks & marblesRocks & marbles Filtration: separates a solid from a liquid in a heterogeneous mixtureFiltration: separates a solid from a liquid in a heterogeneous mixture Paper Chromatography: separation of dyes and inksPaper Chromatography: separation of dyes and inks

DISTILLATION: a liquid is boiled to produce vapor that is condensed again into a liquid.

States of Matter Solid Definite shape Definite volume Particles densely packed Particles vibrate in place Liquid No definite shape Definite volume Particles move freely past one another, cause flow like quality Gas No definite shape No definite volume Particles collide with enough force to escape the attraction of neighboring particles Highly compressible Vapor A substance in a gaseous state that is usually a solid or liquid at room temperature

4 th State of Matter? Plasma  Closely related to gases  Particles are neither molecules or atoms, but rather electrons and positive ions  Formed at very high temperatures (high enough to ionize the atoms)  Move freely like the particles of a gas  Examples Stars, comets, and aurora borealis

PURE SUBSTANCES PURE SUBSTANCES ARE Elements or CompoundsPURE SUBSTANCES ARE Elements or Compounds

Pure Substances and Mixtures

Classification of Matter MATTER Can it be physically Separated ? yesno mixture Pure substance Is it uniform? yesno Homogeneous solution Heterogeneous Can it be chemically separated yesno compound element