Physical and Chemical properties Notes # 1

Physical properties can be observed and measured without changing the kind of matter being studied. They can be used to classify materials, such as metals and nonmetals Metals have the following properties: Luster, good conductors, malleable, ductile and high density Nonmetals are dull insulators(nonconductors) and brittle

Melting point: the temperature at which a solid can change to a liquid. For pure substances a melting point is constant and can be used to identify an unknown substance. example: ice melts to liquid water at 00 C and 320 F.

Boiling point: the temperature at which a liquid changes to a gas. In pure substances at sea level, boiling point is a constant temperature. Example: boiling point of pure water at sea level is 1000 C and 2120 F.

Conductivity: the ability to act as an electrical conductor or insulator Conductive material allows an electrical circuit to be completed High conductivity easily allows electricity to flow Poor conductors are called insulators and do not allow electricity to flow Many metals are conductors and nonmetals are insulators

Color Can be used with other physical properties to help identify a material By itself, color is not a good way to identify a substance Absence of color is also a physical property

Hardness and Magnetism Hardness is the relative resistance of a metal or other material to avoid denting, scratching or bending Magnetism reacts to forces exerted by magnets and are either repelled or attracted

Density depends on its state of matter, solid, liquids or gas Density is the relationship between the mass of a material and its volume. Density depends on its state of matter, solid, liquids or gas High density material has more matter in a smaller space Density is a constant amount, no matter whether you have a large amount or small amount of a material.

Density formula: density =mass/volume Grams are used for mass measurement Centimeters cubed or cm3 is used for volume of solids Milliliters or ml is used for volume of liquids density tells us how much stuff is in a certain space For example: some of you have lockers with high density and it is time to clean them out. : )

Density problem Using the density formula If the mass of an object is 20 grams and the volume of the object is 10 ml, what is the density of the object? Formula d=m/v d=20g / 10ml Density = 2g/ml We compare density of an object to water’s density: If density is less than 1g/ml the object will float If density is greater that 1g/ml than the object will sink Will the above object sink or float?

Chemical Properties: can be recognized only when substances react chemically with one another; they are not usually visible 1. Ability to burn: when a substance reacts with Oxygen quickly to release light and heat energy 2. Ability to rust: when a substance reacts slowly with oxygen over a period of time 3. Chemical reactivity: the tendency of a substance to react with another substance When a substance reacts with another substance a change occurs.