2.MATTER & ITS PROPERTIES:

MATTER & ITS PROPERTIES:

Properties of Solid:
-A solid has a definite volume and shape; particles have a low kinetic energy.

-The particles held closer by intermolecular forces of attraction. Because the particles are so close together, they appear to vibrate around a fixed point.

-When the temperature of a solid is raised, the velocity of the particles increases.

-The collisions between the particles occur with greater force, causing the particles to move farther apart. The ordered arrangement of the solid breaks down and a change in physical state occurs.

Types of solids

crystal	A solid with an orderly, three-dimensional pattern that repeats itself over and over again.
amorphous	Solids whose atoms are not arranged in any orderly and repetitive manner
Quasi-crystalline	orderly three-dimensional pattern, but it does not repeat itself as regularly as crystals do
composite	solids are composed of several different materials bonded together

Properties of Solids

Ductility	ability of a solid to be drawn out into fine threads. E.g. Tungsten, Quartz
Malleability	is the extent to which a solid can be hammered or rolled into sheets. E.g. gold
Hardness	resistance to scratching e.g. diamond, corundum and topaz etc. Moh’s Scale is used to indicate the degree of hardness.
Brittleness	tendency to crumble when subjected to blow. E.g. Rock Salt
Elasticity	ability of an object to return to its original size or shape when external forces are removed. E.g steel
Strength	the ability of a solid to withstand a load without failure
Stress (Force/Area)	The force per unit area which tend to distort the body
Strain	The relative amount of distortion produced in the body
Fatigue	failure of solid when a repeated (and possibly small) cyclic stress is applied

-Hooks Law states that, within certain limits, strain is directly proportional to stress.
-Young’s Modulus is a measure of the stiffness of materials, or elasticity.

    Young’s modulus = stress/strain

Liquid
-A liquid has a definite volume but not a definite shape and particles have enough kinetic energy to stretch the intermolecular forces of attraction.

-The particles in a liquid tend to move around. This movement, known as Brownian movement, occurs because each particle in a liquid is continually being bombarded by other particles in the surrounding liquid.

-Because of Brownian movement, molecules in liquids are in constant, rapid, and random motion.

-As the temperature of a liquid is raised, the velocity of the particles increases.

-The collisions eventually become so great that the particles break all intermolecular forces, begin moving independently between collisions, and a change in physical state occurs

Properties of Liquid:
Surface tension
-Surface tension is the tendency of a liquid surface to contract and occupy the minimum area possible.

- Small droplets of liquid tend to be spherical because for a given volume of liquid the spherical shape requires the smallest surface area.

-The surface tension produces the effect of thin skin covering on a liquid.

-Small insects can walk or run on this surface.

-The rise in temperature and impurities reduces the surface tension.

- The modern detergents, the floating of needle in on the surface of the liquid and the ability of the duck to swim because the feathers are not wet are the examples of surface tension.

Capillarity

- Capillarity is elevation or depression of the surface of a liquid where it is in contact with a solid, such as the sides of a tube.

-This phenomenon is an exception to the hydrostatic law that a liquid seeks its own level.

- It is most marked in capillary tubes (Latin capillus,”hair”), that is, tubes of very small diameter.

-Capillarity depends on both the cohesive and adhesive properties of the liquid.

- Liquids rise in capillary tubes they wet and are depressed in tubes they do not wet ( e.g. Mercury).

-The absorption of water in a sponge and the rise of molten wax in a wick are familiar examples of capillary rise.

- Water rises in soil partly by capillarity.

Viscosity
-Viscosity is the property of a fluid that tends to prevent it from flowing when subjected to an applied force.

- High-viscosity fluids resist flow; low-viscosity fluids flow easily.

-The viscosity of a fluid decreases with a decrease in density that occurs when the temperature increases.

-In a less dense fluid, fewer molecules are available per unit volume to transfer the motion from the moving layer to the stationary layer.

- This in turn affects the speed of the different layers.

Cohesion	The force of attraction between molecules of the same kind.
Adhesion	The force of attraction between molecules of different kinds.

Gas
-A gas has neither definite volume nor shape and particles have enough kinetic energy to break all intermolecular forces of attraction.

- Gases will expand indefinitely to completely fill the container in which they are placed.                                                                                                                                             -Gases exert a pressure on the walls of the container in which they are placed. This is a result of the fact that gas molecules move independently of one another and often at high speeds.                                                                                                                                                                                                         -The molecules of gases exert no attractive or repulsive forces on each other.                                                                                                                                                       -Gases diffuse. Gases will diffuse and mix completely with other gases, forming a completely homogenous mixture.                                                                                                                                                                                                                               -The diffusion of gases is much quicker than that of liquids.                                                                                                                                               -Gases will also diffuse through solids and liquid                                                            - Gases have  special relationships involving their temperatures, volumes, and pressure.

Plasma
-Plasma(a special form of gas) - a plasma can be defined as a charged gas.

-However, at extremely high temperatures and pressures, the particle collisions are violent enough to break electrons out of the atoms, producing particles with charges (electrons and positive ions).So capable of conducting electricity.                                                                                                            -These type extreme conditions exist naturally in stars.                                                                                                                                                                  - A practical real-life application of plasma occurs in the formation of thermonuclear reactions.

Pressure
-Pressure (p) is a measure of force per unit area.                                                            - The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N•m^-2 or kg•s^-2•m^-1).                                                                                                 -Static pressure is the pressure due to the density and depth of a fluid.

-Stagnation pressure is the pressure due to the velocity of a fluid, and is defined to include static pressure.                                                                                     -Liquids exert pressure due to distribution of their own weight.

Bernoullis Principle
-Bernoulli’s Principle states that when the speed of a fluid in a pipeline increases, the pressure decreases and conversely when the speed of a fluid decreases, the pressure increases.
Some examples
-The jet water pump works on this principle. It also explains why two speedboats moving parallel and close to each other are likely to be pulled together and collide. A more useful example is provided by the functioning of a perfume bottle: squeezing the bulb over the fluid creates a low pressure area due to the higher speed of the air, which subsequently draws the fluid up. Another example of Bernoulli’s principle at work is in the lift of aircraft wings and the motion of curve balls in baseball. In both cases the design is such as to create a speed differential of the flowing air past the object on the top and the bottom - for aircraft wings this comes from the movement of the flaps, and for the baseball it is the presence of ridges. Such a speed differential leads to a pressure difference between the top and bottom of the object, resulting in a net force being exerted, either upwards or downwards.

Pascal’s Law
- Pascal’s Law states that pressure exerted at a point in an enclosed (and non-compressible) liquid is transmitted equally in all directions.                       -The pressure is transmitted undiminished.

-Applications of Pascal’s law are plenty. The most common use this has is in hydraulic lifts, car brakes etc.

Boyle’s & Charles laws
-Boyle’s law states that the pressure of a gas times its volume is equal to a constant number, for a gas at a constant temperature.                                            -This relationship means that pressure increases as volume decreases, and vice versa.                                                                                                                                            -Charles Law gives the manner in which the volume of a gas changes with temperature.                                                                                                                                     -The law states that for a constant pressure on a given mass of gas, the volume is directly proportional to the temperature.

Atmospheric Pressure
-Atmospheric pressure is the pressure caused by the weight of air above any area in the Earths atmosphere.                                                                                                 - A barometer is an instrument used to measure atmospheric pressure.                                                                                                                          -Barometer was first deviced by Evangelista Torricelli.                                                                                                                                  -Another type of barometer, the aneroid barometer, is also used .                         -A barometer is commonly used for weather prediction as high air pressure in a region indicates fair weather while low pressure makes storms more likely.                                                                                                                                                               - A manometer is a pressure measuring instrument.                                                                                                                                   -The standard at sea level pressure is 760 mm of Hg.                                                                                                                                                             -Some Applications: The ordinary lift pump raises water from a well because of atmospheric pressure. It pushes down the water and forces it up the pipe which connects the well and the pump. The atmospheric pressure makes it possible to move liquids by siphon from a higher level to lower level.

Buoyancy and Archimedes Principle
When a body is immersed in a liquid, it seems less weigh but when the same body seems too heavy when it comes out of the liquid. The liquid exert an up thrust on a body immersed in it is called buoyancy and the upthrust is called buyonant force. It depends on the size or volume of the body and the density of the liquid. Air is also buoyant but less buoyant than liquid.

Archimedes Principle
Archimedes principle states that when a solid body is wholly or partially immersed in a fluid, it experiences an upward thrust or buoyant force equal to the weight of the fluid displaced by the body. This principle, also known as the law of hydrostatics, applies to both floating and submerged bodies, and to all fluids.
Some examples:

 A solid that is denser than the liquid in which it is placed will sink. If it is less dense than the liquid it will float. This explains why a nail or iron sinks in water while a large ship made up of iron floats. The same principle explains why lead float on mercury, kerosene floats on water and cream rises in milk and float on it. A hydrometer is an instrument based on the principle of flotation and is used to measure, the relative density of a liquid in which it floats.