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Monday, December 27, 2010

What are radioactive elements on the periodic table?

Definition of radioactive elements:
Radioactive elements are those elements whose atoms have an unstable nucleus as a result of which they emit certian electromagnetic radiations like Alpha, Beta and Gamma radiations.

Explanation of radioactive elements:
Radio active elements emit radiations like Alpha, Beta and Gamma radiations.
Alpha, Beta and Gamma radiations are a type of electromagnetic waves, like visible light. The atoms of radioactive elements in their natural state emit these radiations.
The nucleus of the atoms of radioactive elements is unstable
The nucleus in any atom contains protons and neutrons. The number of neutrons is generally equal to the number of protons for any element. But there are elements in which the number of neutrons per nucleus is greater than the number of protons. This causes the nucleus of those elements to become unstable. It tries to lose the extra mass so that the number of neutrons becomes equal to the number of protons.
For losing the extra mass, the nucleus of the element starts emitting its subatomic particles, that is, neutrons, protons, and electrons in the form of electromagnetic radiations known as Gamma, Alpha and Beta radiations.

Position of radioactive elements in the periodic table
Radioactive elements have an unstable nucleus. The number of neutrons in the nuclei of radioactive elements is larger than the number of protons. This occurs generally in elements that have a large atomic mass. The elements having larger atomic masses are present in the lower rows of the periodic table. In general, all elements after Lead (Pb) in the periodic table have an unstable nucleus, and they all have high atomic masses.

The two rows at the bottom of the periodic table consist of radioactive elements. These are known as the rare earth metals. These are heavy metals since they have high atomic masses.
The first row elements are known as the Lanthanide series of elements, since their first element is Lanthanum. The second row of elements is known as the Actinide series of elements, since their first element is Actinium. These are all radioactive elements (rather metals).

Why are the two rows placed at the bottom of the periodic table? These are the elements that should come in the sixth and seventh rows of the periodic table. But representing them in their respectable rows would highly distort the shape of the periodic table. Therefore these elements are put in tow rows at the bottom of the periodic table, to maintain the shape of the periodic table.

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  5. lanthanides are not radioactive

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