+What is Chemistry?

• What is Chemistry?

Chemistry is a basic science whose central concerns are -

• the structure and behaviour of atoms (elements)

• the composition and properties of compounds

• the reactions between substances with their accompanying energy exchange

• the laws that unite these phenomena into a comprehensive system.

Chemistry is not an isolated discipline, for it merges into physics and biology. The origin of the term is obscure. Chemistry evolved from the medieval practice of alchemy. It's bases were laid by such men as Boyle, Lavoisier, Priestly, Berzelius, Avogadro, Dalton and Pasteur.

Chemistry is the study of matter and energy and the 

interactions between them. This is also the definition 

for physics, by the way. Chemistry and physics are 

specializations of physical science. Chemistry tends 

to focus on the properties of substances and the 

interactions between different types of matter, 

particularly reactions that involve electrons.

chem·is·try n., pl. -tries. 1. the science that systematically studies the composition, properties, and activity of organic and inorganic substances and various elementary forms of matter. 2. chemical properties, reactions, phenomena

What Are Types of Chemical Reactions

Chemical Reactions: Synthesis

A synthesis reaction occurs when two or more elements or compounds combine and create a new and more complex product (A+B--->C). An example of a synthesis reaction is the combination of sulfur and iron to form iron sulfide.  

Chemical Reactions: Decomposition

A decomposition reaction is one where a compound breaks down into smaller and less complex elements or compounds (AB--->A+B or ABC--->A+B+C). An example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas.  

Chemical Reactions: Single Displacement

A displacement reaction is a reaction where an element replaces, or displaces, a less active element in a compound. Iron will replace copper in a copper II chloride solution, producing iron II chloride and copper.

Chemical Reactions: Double Displacement

A double displacement reaction is a reaction where two compounds react and form new compounds. The formation of more stable compounds, such as of a water or a precipitate, powers these reactions (AB+CD--->AD+CB). Barium nitrate and sodium sulfate will form barium sulfate, the precipitate, and sodium nitrate.

Chemical Reactions: Combustion

A combustion reaction is an exothermic reaction that occurs when oxygen and another element or compound are combined. A basic combustion reactions occurs when carbon in the form of charcoal reacts with oxygen to form carbon dioxide and heat.