Physical Science Ch.5 State of Matter V.Y. Maverick B.T

Atoms and Molecules A fluid is a form of matter that flows when any force is applied, no matter how small. The best example of fluids are Liquids and Gases. Molecules in liquid, phases of matter that can flow and change shape but have constant volume, have space to move around, but the molecules are tighter than gas. Molecules in a solid object don’t move around at all and are really packed together, so they are not allowed to change shape. Gases are the most free to move because they are far apart, so they can change the shape.

Intermolecular forces In atoms there are two types of actions, the stronger forces are between atoms that bond together into molecules and compounds, the weaker type are between molecules but don’t bond together. Intermolecular forces are forces between separate atoms and molecules that are attractive at a distance, but repulsive at close range. In addition, thermal energy causes molecules to spread apart, and the intermolecular forces are trying to bring them close.

Melting and Boiling Melting point is a temperature in which a substance changes form a liquid to a solid. Ice melts when it is at 0 degree and it’s lacking heat. Added enough thermal energy, and intermolecular forces are completely overcome, the liquid will become gas. Water will boil when the temperature is at 100 degrees.

Melting Points of Common substance Most materials have higher density as a solid than as a liquid. Solid water resembles a honeycomb. The water will freeze because the honeycomb structure spreads slightly within itself, so this causes the volume to increase, but the mass stays the same. Ice will float on the water in winter because it has less density than water. However, the temperature below the water will not freeze, so organisms still can survive during cold weather.

Vocabulary time Amorphous- Solids that don’t have a repeating pattern of molecules or atoms. Polymer- Material in which individual molecules are made long chains of repeating units

In an easy way to represent a polymer is plastic because plastic is in the family of material in polymer. A polymer is when individual molecules gather together to make a long chain of repeating units. Also, polymers are very useful in our lives, like the plastic containers, sandwich bags, etc. all need polymers to be made. The reason they are useful is because they have high melting points, can be easily formed, and when they solidify at a cool temperature, they still have good strength.

Crystalline solids Crystalline is the solid that has a repeating pattern of atoms, so it look like crystal. Most of the naturally occurring solids on Earth are crystalline. The evidence of those things is when you look under the microscope, you can see the shape of crystal. However, metals are also crystalline, but they don’t have the shape like crystal because tiny crystals is fused to be together in a jumble of different orientations. Most part of the crystalline is made from the element silicon that we just learn from the periodic table.

Pressure Pressure is created when a force is applied to a fluid. Pressure will occur in every direction because of the collisions between atoms. Under the microscope, we will see trillions of atoms bouncing off each other and the wall per second. All of this interaction causes pressure. Why ???

The Atmosphere of the Earth Air doesn’t have an actual shape, but it does surrounding us. Air is the most important gas for all living things. In the universe, atmosphere is a kind of air surrounding the earth. Atmosphere is a mixture of nitrogen, oxygen, other gasses, and water vapor.. Rain is represents of the atmosphere that drops rapidly because the warm air saturated with the water vapor. Cold air has more dense than warm air. Warm air needs ground to expand and warm.

Convection is the transfer of heat through the motion of fluids. When we cook dinner in the kitchen, we will feel hot because the air transmits the heat to us. Convection will occur when the fluids expand because of heat. Natural convection occurs when the fluid become heated it will increase the volume but not the mass Hot water will have lower density than the cold; this is the reason why hot water will rise to the top.

Heat Conduction in Solids Heat Conduction – when we hold something hot in our hands, we can feel that heat transfer from the object to our hands. So Heat conduc- tion is the transfer of heat by direct contact of particles of matter. Thermal Equilibrium – a condition where temperature is the same and no heat flows.

Thermal conductors and Insulators Conduction can occur in liquid, gas and solid. Solid is the best conductor because inside the solid molecules are packed closer. Thermal conductors are materials that transfer easily; the opposite are insulator conductors which transfer heat poorly. Examples of thermal conductor materials are silver, copper, gold, etc. Conductions cannot take place in a vacuum space because there is no matter.

Mechanical Properties Four main properties Strength - an object that can obtain, but when it’s over the limit, the object will break. Elasticity - an object that is able to stretch and bounce back. Brittleness - the opposite of elasticity, it cant bend and if you drop it, it will break. Ductility - a solid material's ability to deform under tensile stress.

The End Thank you V.Y, & B.T