States of Matter Chapter 18 in book @home

Particle Theory of Matter Theory states that all matter is made up of tiny particles in constant motion. Thermal Expansion= matter expands as it gets warmer and contracts when it cools. Water is exception!!! Water expands as it freezes.

Particles of Matter Atoms – smallest unit of an element that maintains the properties of that element Molecules – 2 or more atoms combined in a fixed ratio Solids – particles vibrate in fixed locations Liquids – particles slide past one another but are still attracted to one another Gases – particles move very fast; random and rapid

Template from www.brainybetty.com Solids Main characteristics: Definite shape Definite volume 2/25/2019 Template from www.brainybetty.com

Solids Two types of solids: Crystalline= made up of crystals Amorphous= do not keep their shape

Template from www.brainybetty.com Liquids Two characteristics: No definite shape Always take shape of their container 2/25/2019 Template from www.brainybetty.com

Liquids Viscosity= liquid’s resistance to flow… Ex: honey has high viscosity because its slow to move

Liquids Surface tension – a force that acts on particles at the surface of a liquid; causes some liquids to form droplets

Template from www.brainybetty.com Gases Several characteristics: No definite shape No definite volume…expand forever! Fill available space in container 2/25/2019 Template from www.brainybetty.com

Gases Particles can be compressed or pushed together… Ex: bike tire, hair spray can

Template from www.brainybetty.com Plasma Gas-like mixture of charged particles Plasma has high temperatures (energy) Ex: aurora borealis, lightning 2/25/2019 Template from www.brainybetty.com

Change of State Change of state – change of a substance from one physical form to another To change the state, energy must be added or removed

Melting Point Melting= change of solid to liquid. Melting pt. – temp at which a substance changes from a solid to a liquid. Energy must be added…endothermic (the substance gains energy)

Freezing Pt. Freezing=change of liquid to solid. Freezing pt. – temp at which a liquid changes into a solid Energy is removed…exothermic Freezing point of a substance is equal to its melting point.

Vaporization Liquid to Gas Evaporation Boiling Particles throughout Vaporization at the surface of the liquid. The temp may be below the boiling point. Particles throughout the liquid change to a gas. Occurs the pressure inside the bubbles (vapor pressure) equals the outside pressure (atmospheric pressure).

Effects of Pressure on Boiling Point Atmospheric pressure – weight of gases that make up the atmosphere Water boils at 100°C only at sea level As altitude increases, pressure decreases, boiling pt. lowers As altitude decreases, pressure increases, boiling pt. increases

Condensation and Sublimation Condensation= change of substance from a gas to a liquid. Condensation is the same as the boiling pt. at a given pressure Energy is removed…exothermic Sublimation= change of substance from a solid to a gas. Energy is gained…endothermic

Change of Temperature vs. Change of State When substances lose or gain energy, they either change their temperature OR their state. They do not do both at the SAME time. At temperature change does NOT occur until a change of state is complete.

Heat of vaporization Heat of fusion

Solid Liquid Gas