Reactants
The smallest particles of elements that enter into chemical reactions are known as atoms.
Now are known 118 chemical elements.
The force that attracts chemical elements to other elements is known as the ionic bond. This will attract and hold chemical elements together.
Some noble gases as He, Ne, Ar are very unreactive (only rare unstable molecules are known up today) but excepting these elements the other chemical elements are more or less reactive.
A chemical reaction in which two elements or radicals change places with two other elements is called double replacement. It is also known as double displacement. Its general pattern can be written as AB + CD --> AD + CB
Now (22.08.2012) 118 chemical elements are known.
Some noble gases as He, Ne, Ar are very unreactive (only rare unstable molecules are known up today) but excepting these elements the other chemical elements are more or less reactive.
Today are known 118 chemical elements.
There are 118 known chemical elements as of 2011.
A chemical change can be caused by a reaction. It an element or compound reacts with another, it is known as a chemical change.
115 known chemical elements. However, that number is not accurate; there are really more than that now.
Copper turns green due to a chemical reaction with oxygen and other elements in the environment, forming a layer of copper oxide and copper carbonate on the surface. This process is known as oxidation and is a chemical change.