Kinds of Matter

Claimed by Kristen Sparks Claimed by Pranusha Atuluru (Fall 16)

This topic covers the Different Kinds of Matter.

The Main Idea

No matter how how big or small the matter, physics can be applied to all objects. States of matter are differentiated or determined by significant changes that occur due to the alteration of an important property such as specific heat capacity, pressure, or temperature. Specific heat capacity is the heat required to raise the temperature of a unit mass by a given amount (usually by one degree). Pressure is a continuous physical force exerted on or against an object and temperature is the degree of heat present in a substance or object. In different states of matter, things only move from one phase to another through physical means and not chemical where the same chemical properties of the substance is the same.

All matter is made of atoms or molecules. To understand the properties of matter around us we look at atomic properties and interactions. Atomic interactions can be attributed to the attractive and repulsive forces due to the different parts of an atom which are: protons, electrons, and neutrons. Protons are positively charged particles, electrons are negative, and neutrons have no charge. Protons and neutrons make up a small, dense center called a nucleus. Around the nucleus are electrons, whose negative forces are attracted to the positive center.

Solids

Solids is a sample of matter that retains its shape and size even when it is not confined by another object and that occupies a specific area and volume. They are difficult to deform because they are resistant to changes of shape or volume. The molecules in a solid object are usually as confined and packed together as possible or as much as the repulsive forces between the molecules allow. When a solid is heated or when energy is put into a solid, the molecules gain kinetic energy and eventually overcome the forces that hold them in place. If enough kinetic energy is gained, it leads to a phase change where the solid becoming a gas or a liquid.

This is how the molecules are arranged in a solid.

The process where a solid becomes a liquid is called melting. The special temperature at which a solid becomes a liquid is melting point. For example, the melting point of ice is 0 degrees Celsius where the ice becomes liquid water. There is also a process where solid becomes a gas called sublimation. This occurs with dry ice (solid CO2) that becomes gas as soon as it is put out in room temperature.

There are two main categories of solids called crystalline solids and amorphous solids. Crystalline solids are solids where the atoms of molecules that make up the solid are arranged in a neat, well-defined arrangement. Four types of crystalline solids include ionic, molecular, atomic, and metallic solids. Amorphous solids are those in which the molecules do not have much arrangement. Although the molecules are close together and have little freedom to move, they are not as well-defined in arrangement as crystalline solids.

Liquid

Liquid is a phase of matter that can flow, change its shape, and eventually take the shape of the container that it is placed within. It is not very compressible and maintains a relatively fixed volume. Liquids are made up of molecules that are close together like a solid, but they do not have a defined arrangement. The molecules are able to vibrate, move and slide past each other in a liquid, which is what allows for changes in shape.

Gases bounce everywhere and spread out but many liquids want to stick together due to intermolecular forces called cohesive (sticky) forces that act to pull the molecules together. These attractive forces exist between molecules of the same substance and resist separation of a liquid. The liquid can overcome these cohesive forces when the weight reaches a certain point.

When a liquid, the molecules within it gain kinetic energy much like the molecules in a solid. When the molecules gain enough energy, the liquid is able to phase change into a gas through a process called evaporation. The temperature at which a liquid becomes a gas is called boiling point. For example, the boiling point of liquid water is 100 degrees Celsius.

Gas

A gas is a sample of matter that has no definitive shape much like a liquid, but expand to occupy the entire available volume. The molecules in the gaseous state move freely among each other and packed more loosely than the molecules of the same substance in the solid or liquid state. This state of matter is what exists between the liquid and plasma phase, and is usually invisible to the human eye due to the large separation between the molecules. Gases have looser intermolecular bonds than liquids and solids and these bonds exist due to electrostatic interactions between the gas particles where like-charged areas repel and opposite-charged areas attract.

When energy is taken out of a gaseous phase, the molecules lose kinetic energy and stop colliding as much. The process in which a gas becomes a liquid is called condensation and occurs at the same temperature as the boiling point. A gas can directly turn into a solid through a process called deposition. An example of this is when CO2 in air sometimes freezes to directly become a solid, skipping over the liquid phase.

Plasma

Like a gas, plasma does not have a definitive shape or volume; therefore, it can expand to occupy the maximum amount of volume available. However, unlike a gas, plasma is made up of ionized molecules that carry electric charge. The entire gas as a whole has no electric charge however, and the density of this gas isn't too high. Plasma exists when positively charged nuclei are floating around in an area of free-floating electrons; it consists of approximately equal numbers of positively charged ions and negatively charged electrons.This makes plasmas electrically conductive and allows allows it to produce magnetic fields or electric currents.

Most plasmas aren't dense enough for particles to collide with one another very often, so the magnetic and electrostatic interactions become more important. Since there are free floating electrons and ions in plasma, the molecules can interact as far greater distances than ordinary gases through electricity and magnetism. Another important characteristic of plasmas is that they can be held in place using magnetic fields, which is different from all the states of matter discussed before.

There are two ways by which a gas can be converted into plasma: 1) either from a huge voltage difference between two points, or 2) exposing it to extremely high temperatures. Heating matter to high temperatures or exposing it to a huge voltage difference causes electrons to leave the atoms, resulting in the presence of free electrons. These free floating charged particles contributes to plasma being electrically conductive.

Planets, Stars, Solar Systems and Galaxies

Plants and stars make up solar systems, and multiple solar systems make up galaxies.

Point Particles

Point particles are often used to analyze more complicated/large objects. Physicists assume that these objects have been compressed into structures where size, shape and internal structure are not taken into consideration: a tiny speck with equivalent mass as the object its representing.

Examples

Atom

Crystalline Solid

STM Image

Connectedness

The different kinds of matter are important to understanding how physics can be applied to everyday life. It helps connect the misunderstood atomic and subatomic level to something that everyone can understand. More advanced physics will correlate atomic bonds to springs, a juxtaposition that helps explain a complex interaction with a simple explanation.

History

The first theories on atomic and subatomic particles began with J. J. Thompson in 1897, when he discovered electrons. An idea made the scientific community realize that atoms were not the smallest particles of matter. Then in 1909 Ernest Rutherford started experimenting with gold and alpha particles, and experiment that lead to the discovery of nuclei.

These fundamental discoveries lead to the deep understanding of the atomic world that scientists have today. Without them the properties of matter and physics would be a grayer area of science.

References

Matter and Interactions By Ruth W. Chabay, Bruce A. Sherwood - Chapter 1

http://www.sparknotes.com/testprep/books/sat2/physics/chapter19section2.rhtml