Unit 02 : Lesson 2

Physical and Chemical

Properties

Recall: • Physical change: (reversible)

composition does not change, just appearance

• Chemical change: (irreversible) composition changes into a new substance.

Physical Properties• Physical Properties:

can be observed or measured without changing the composition of matter. Physical properties are used to observe and describe matter.

• Include density, magnetism, color, luster, ductility, viscosity, malleability, and conductivity.

Characteristics of Physical Properties• Density: "heaviness" of objects with a

constant volume. D = M / V• Magnetism: force of attraction or repulsion

between various substances, especially those made of iron and certain other metals; ultimately it is due to the motion of electric charges.

Cont. physical properties

• Color• Luster: the state or

quality of shining by reflecting light; glitter, sparkle, sheen, or gloss

• Ductility: ability of a metal to plastically deform without breaking or fracturing,

Cont. physical properties

• Malleability: property of a metal describing the ease with which it can be hammered, forged, pressed, or rolled into thin sheets

• Conductivity: a measure of a material's ability to conduct an electric current and heat

Cont. physical properties

• Viscosity: the resistance for liquid to flow

Chemical Properties• Chemical properties: allow a substance to react forming new substances.

• Include: corrosiveness, flammability, and oxidation.

Characteristics of chemical change

• Corrosiveness: having the quality of corroding or eating away; erosive

• Flammability: how easily something will burn or ignite, causing fire or combustion.

Cont. chemical properties

• Oxidation: The combination of a substance with oxygen. A reaction in which the atoms in an element lose electrons and the valence of the element is correspondingly increased.

Materials can be classified as: (Each category has its own distinct properties).

• Metals: shiny, ductile, malleable and good

conductors of heat and electricity. • Nonmetals: generally poor conductors of

heat and electricity.• Metalloids: have some chemical/physical

properties of metals and some properties of nonmetals. – Si, Ge, As are semiconductors (conduct electricity

slightly better than a nonmetal, but not as well as a metal.

Your Turn:

• Give an example of a chemical change• Give an example of a physical change• Give a characteristic of a chemical property.• Give a characteristic of a physical property.• Who are great conductors? Metals or

Nonmetals• Who have both characteristics of both metals

and nonmetals?