Chemistry is the science of matter at or near the atomic scale. (Matter is the substance of which all physical objects are made.)
Chemistry deals with the properties of matter, and the transformation and interactions of matter and energy. Central to chemistry is the interaction of one substance with another, such as in a chemical reaction, where a substance or substances are transformed into another. Chemistry primarily studies atoms and collections of atoms such as molecules, crystals or metals that make up ordinary matter. According to modern chemistry it is the structure of matter at the atomic scale that determines the nature of a material.
Chemistry has many specialized areas that overlap with other sciences, such as physics, biology or geology. Scientists who study chemistry are called chemists. Historically, the science of chemistry is a recent development but has its roots in alchemy which has been practiced for millennia throughout the world. The word chemistry is directly derived from the word alchemy.
In addition to the specific chemical properties that distinguish different chemical classifications, chemicals can exist in several phases. For the most part, the chemical classifications are independent of these bulk phase classifications; however, some more exotic phases are incompatible with certain chemical properties. A phase is a set of states of a chemical system that have similar bulk structural properties, over a range of conditions, such as pressure or temperature.
Physical properties, such as density and refractive index tend to fall within values characteristic of the phase. The phase of matter is defined by the phase transition, which is when energy put into or taken out of the system goes into rearranging the structure of the system, instead of changing the bulk conditions.
Sometimes the distinction between phases can be continuous instead of having a discrete boundary’ in this case the matter is considered to be in a supercritical state. When three states meet based on the conditions, it is known as a triple point and since this is invariant, it is a convenient way to define a set of conditions.
The most familiar examples of phases are solids, liquids, and gases. Many substances exhibit multiple solid phases. For example, there are three phases of solid iron (alpha, gamma, and delta) that vary based on temperature and pressure. A principal difference between solid phases is the crystal structure, or arrangement, of the atoms. Another phase commonly encountered in the study of chemistry is the aqueous phase, which is the state of substances dissolved in aqueous solution (that is, in water).
Less familiar phases include plasmas, Bose–Einstein condensates and fermionic condensates and the paramagnetic and ferromagnetic phases of magnetic materials. While most familiar phases deal with three-dimensional systems, it is also possible to define analogs in two-dimensional systems, which has received attention for its relevance to systems in biology.
|Atomic Structure – Chemistry||01:15:00|
|Hydrocarbon – Chemistry||01:01:00|
|Mole Concept – Chemistry||01:06:00|
|Name Reaction – Chemistry||FREE||01:01:00|
|Periodic Table and Periodicity – Chemistry||01:14:00|
|Radioactivity – Chemistry||01:11:00|
|Redox – Chemistry||01:26:00|
|Solution and Colligative Properties – Chemistry||01:21:00|
|Chemical Bonding – Chemistry||01:06:00|
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