States of Matter

Ch 4.1 - MatterA. Matter – anything that has mass and

takes up space; all matter is composed of tiny particles called atoms

1. There are 3 usual states of matter – solids, liquids and gases

2. The 4th state is plasma which occurs at extremely high temperatures and is not common on Earth

B. The 4 states of matter

1. Solids – matter with a definite shape and volume

a) Particles are in motion but fixed in place; they do not have enough energy to leave their fixed positions

b) Crystalline solids (aka crystals) – the atoms are arranged in a repeating 3-dimensional pattern

c) Amorphous solids – solids that do not form crystals because particles are not arranged in repeating patterns

2. Liquids – matter that has a definite volume but no definite shape

a) The particles have enough energy that they can move and slip past each other

b) Viscosity – a liquids resistance to flow

c) Surface Tension – attractive forces cause the particles on the surface of a liquid to pull themselves together and resist being pulled apart

3. Gases – matter that does not have a definite shape or volume

a) Particles move at high speeds in all directions

b) Will spread out as far as possible

c) Gas can expand or compress

d) Vapor – matter that exists in the gas state but generally is a liquid or solid at room temperature

4. Plasma – matter found at extremely high temperatures such as in stars and lightening

a) Most common state in the universe

b) Atoms in this state lose their electrons

Ch 4.2 – Changes of StateA. To change the state of matter of a

substance you must add or remove energy

1. Energy – the ability to do work or cause change

a) Thermal energy – total energy of all particles in a sample of matter

b) Temperature – an average kinetic energy of each individual particle in a substance

c) Heat – the movement of thermal energy from a substance with a higher temperature to one with a lower temperature

B. Specific Heat – the amount of heat required to raise the temperature of 1 gram of a substance 1oC

1. Low specific heat – heats up and cools down quickly (ex: metal & sand)

2. High specific heat – heats up and cools down slowly (ex: water)

C. Changes between solid & liquid states

1. Matter can change from one state to another when thermal energy is absorbed or released

2. There are several changes of state that can occur:

a) Melting – a change from solid to liquid by the addition of thermal energy. The temperature at which this occurs is called its melting point

b) Freezing – a change from a liquid to a solid by removing thermal energy. The temperature at which this occurs is called its freezing point

D. Changes between liquid & gas states

1. Vaporization – the change from a liquid to a gas. There are 2 types:

a) Boiling – vaporization that takes place below the surface of a liquid

b) Evaporation – vaporization that takes place on the surface of a liquid

2. Condensation – the opposite of vaporization; when particles slow down, lose thermal energy and change of state goes from a vapor (gas) to a liquid

3. Sublimination – change from a solid directly to a gas without going through the liquid phase

Ch 4.3 – Behavior of FluidsA. Pressure – a force exerted on a surface divided by

the total area over which the force is exerted

1. Force – a push or pull on an object

2. P = F / A [Pressure = force (N) ]

3. N = pascal (Pa)

area (m2)

m2

4. Atmospheric Pressure – the pressure that the Earth’s atmosphere (air) exerts on us and everything on Earth in all directions

a) Atm. Pressure is measured in kPa (1000 Pa)

b) Earth’s atm. Pressure is equal to 101.3 kPa

c) We don’t feel this extreme force because our body is exerting a pressure equal to the atm. Pressure in the opposite direction (balanced forces)

d) Atm. Pressure changes with altitude; as you rise in altitude it decreases because there are fewer air molecules; ears “pop” because there is greater pressure inside pushing out than being pushed on you

B. Gas pressure in a closed container changes with volume and temperature

1. Pressure & Volume

a) in volume = in pressure

b) in volume = in pressure

2. Pressure & Temperature

a) in temp = in pressure

b) in temp = in pressure

C. Float or Sink

1. Buoyant Force – the upward force on an object immersed in a fluid

2. Archimedes Principle – the buoyant force on an object is equal to the amount of water weight it displaces when submerged

3. If the buoyant force is equal to or greater than the weight of the object it will float; if it’s less than the weight the object will sink

4. Density – mass divided by volume

a) An object will float if the fluid is more dense

b) An object will sink if the fluid is less dense

c) If densities are equal the object will not sink or float but remain suspended

D. Pascal’s Principle – when a force is applied to a confined fluid, an increase in pressure is transmitted equally to all parts of the fluid

1. Hydraulic systems – allow people to lift heavy objects with relatively little force

2. Force pumps – in a closed container that has a hole, any fluid in the container will be pushed out of it