Physical Science-CH.2

pure substance

pure substance

a material made of only one kind of element or compound

it is not a mixture

element

a pure substance that consists of atoms with the same atomic number

Compound

a pure substance consisting of atoms of two or more different elements that are chemically combined

mixture

a physical combination of two or more substances in a changeable ratio

heterogenous mixture

a mixture that is not uniform in appearance or composition

components are not evenly distributed throughout the mixture

homogeneous mixture

a mixture that is uniform in composition

components are evenly distributed and not easily distinguished (aka, solution)

Solid

A state of matter that has a definite shape and a definite volume

liquid

A state of matter that has a definite volume but not a definite shape.

gas

a form of matter that does not have a definite volume or shape

plasma

the most common state of matter in the universe, mainly found in the sun and other stars

viscosity*

A liquid's resistance to flowing

physical property

a characteristic that can be observed or measured without changing the identity of the substance

ductility*

the ability of a substance to be pulled into a wire

mallebility*

the ability of a material to be hammered, pressed, or rolled into thin sheets

conductivity*

the ease with which a material allows the transfer of either electrical or thermal energy

luster*

the quality of how a mineral reflects light from its surface

physical change

A change in a substance that does not change its identity

chemical change

A change that occurs when one or more substances change into entirely new substances with different properties.

chemical property

how a substance changes in the presence of another substance under certain conditions

reactivity*

the degree to which a material will react with other substances

flammability*

A material's ability to burn in the presence of oxygen

melting point

The temperature at which a solid becomes a liquid

Vaporization

The change of state from a liquid to a gas

law of conservation of matter

Matter is not created nor destroyed in any chemical or physical change

condensation

The change of state from a gas to a liquid

sublimation

A change directly from the solid to the gaseous state without becoming liquid

matter

Anything that has mass and takes up space

law of definite proportions

the law that states that the masses of chemical substances combine in definite, characteristic integer ratios when forming compounds.

particle model of matter

a model that states that all physical matter exists in the form of particles.

atom

Building block of matter

contains subatomic particles: (usually) neutrons, protons, and electrons.

molecule

a particle consisting of two or more atoms covalently bonded together

mass

A measure of the amount of matter in an object

volume

the space enclosed or occupied by an object

density

the mass pure unit volume of an object

weight

the force of gravity acting on the matter in an object

melting

the change in state from a solid to a liquid

freezing

the change in state from a liquid to a solid

evaporation

The change of a substance from a liquid to a gas

boiling

the relatively fast form of vaporization in which the energy within a liquid creates higher pressure within the liquid than the air pressure outside the liquid

boiling point

The temperature at which a substance changes from a liquid to a gas

deposition

the process in which a gas changes directly into a solid

constant, random

all matter is made of tiny particles (atoms and molecules), in _________ motion

density

this is calculated by dividing the mass of an object by its volume