chapter 7 notes science

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matter is made up of particles in ______ and _____ motion

constant and random

Three states of matter

solid, liquid , gas

expansion and contraction

expansion ^ when a substance in a solid is heated, its particles gain energy and vibrate more vigorously about their fixed positions. The distances between the particles increase. This causes the volume of the substance to increase. As a result, the substance expands.

Contraction ^ conversely, when a substance in the solid state is cooled, its particles loose energy and vibrate less vigorously about their fixed positions. The distances between the particles decrease. This causes the volume of the substance to decrease. As a result, the substance contracts

Melting definition

-process in which a solid changes into a liquid without a change in temperature

Boiling definition

-process in which a liquid changes into a gas without a change in temperature

melting

when a solid is heated, it particles gain kinetic energy . They vibrate faster about their fixed positions. They eventually gain enough energy to overcome the strong forces of attraction between them . the solid melts and becomes a liquid

Boiling

when a liquid is heated, its particles gain kinetic energy. They move faster and further apart from one another. they eventually gain enough energy to overcome strong forces of attraction between them. the liquid boils and becomes a gas.

freezing

when a liquid is cooled, its particles lose energy and move slower. this cause the particles to be pulled much closer to one another by the forces of attraction between them. the particles are eventually held in fixed positions. the liquid freezes and becomes a solid

condensation

when a liquid is cooled, its particles lose energy and move slower. this cause the particles to be pulled closer to one another by the forces of attraction between them. the gas condenses and becomes a liquid

Diffusion definition

-net movement of particles from a region of higher concentration to a region of lower concentration

forces of attraction, movement, arrangement, physical properties of substance in the state

Description of particles	Solid	Liquid	Gas
Forces of attraction	• Held together by very strong forces of attraction	• Held together by strong forces of attraction	• Held together by weak forces of attraction
Movement	• Vibrate about fixed positions	• Able to move about randomly and slide past one another	• Able to move about randomly and quickly
Arrangement	• Very closely packed in orderly manner • Fixed, regular pattern	• Closely packed in disorderly manner • No fixed regular pattern	• Far apart from each other in a disorderly manner • No fixed, regular pattern
Physical properties of substance in the state	• Has definite shape and volume • Has a higher density than liquids and gases • Cannot be compressed	• Has no definite shape, but has a fixed volume • Has a lower density than solids but higher than gases • Cannot be compressed	• Has no definite shape or volume • Has the lowest density among the three states of matter • Can be compressed