Physical and Chemical Properties

Physical Properties • Matter has physical and chemical properties (characteristics) • Physical properties can be seen without changing the identity of the substance – state of matter, color, odor, taste – luster, hardness, malleability, ductility – weight, volume, mass, length, density – melting, boiling, and freezing point – electrical conductivity

Chemical Properties • Cannot be seen without altering the chemical identity of substance – How something reacts when heated or in the presence of air, water, acids, bases, or other chemicals – Flammability, toxicity, oxidation state, stability in a given environment

Physical Changes • Changes in physical properties but not in chemical composition • Caused by motion, temperature, pressure, etc .• Examples– melting, freezing, condensing, dissolving, evaporating, diluting, breaking, crushing, cutting, bending –Includes changes of states of matter! • Why?

Chemical Changes • When one substance changes into one or more new substances in which the atoms are arranged in different ways – cooking, rusting, burning – fermenting, souring – photosynthesis, digestion – electrolysis – other chemical reactions

Signs of a Chemical Change • Gas bubbles • Precipitation (solid forms) • Color, temperature, or volume changes • Light given off • Melting pt, boiling pt, conductivity changes • Smell or taste changes

Changing State Changing state is a PHYSICAL change. It is still the same chemical, the particles are just moving at a different speed

INTENSIVE/EXTENSIVE PROPERTIES • Intensive property- doesn’t change no matter how much matter is present. – the density of a gold coin and a gold statue are the same (19.3 g/cm3), even though the statue consists of a much greater quantity of gold • Mass and volume are examples of extensive properties. They DO change with the quantity present. Mass of gold coin is different from mass of gold statue