Ch. 2 - Classification of Matter I. Describing Matter  Physical Property  Physical Change  Chemical Change  Chemical Property MATTER

A. Physical Property  A characteristic of a substance that can be observed without changing its identity.  can be used to separate mixtures  EX: magnetism, density

B. Physical Change  A change in the form of a substance without changing its identity.  properties remain the same  reversible  can be used to separate mixtures  EX: dissolving, grinding

C. Chemical Change  A change in the identity of a substance.  properties change  irreversible  Signs: color change, formation of a gas/solid, release of light/heat  EX: burning, rusting

D. Chemical Property  A characteristic that indicates whether a substance can undergo a specific chemical change.  EX: flammability, reactivity

Ch. 2 - Classification of Matter II. Composition of Matter  Matter Flowchart  Pure Substances  Mixtures MATTER

A. Matter Flowchart MATTER Can it be separated by physical means? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement MIXTUREPURE SUBSTANCE yesno Can it be decomposed by chemical means? noyes Is the composition uniform? noyes

B. Pure Substances  Element  matter composed of identical atoms  EX: copper

B. Pure Substances  Compound  matter composed of 2 or more elements in a fixed ratio  properties differ from those of individual elements  EX: salt (NaCl)

C. Mixtures  Variable combination of 2 or more pure substances.  Homogeneous Mixture (Solution)  even distribution of components  very small particles  particles never settle  EX: saline solution

C. Mixtures  Heterogeneous Mixture  uneven distribution of components  colloids and suspensions  EX: granite

C. Mixtures  Colloid  medium-sized particles  Tyndall effect - particles scatter light (looks cloudy)  particles never settle  EX: milk

C. Mixtures  Suspension  large particles  particles scatter light  particles will settle (needs to be shaken)  EX: fresh-squeezed lemonade