Definitions (Classification of Elements)
CLASSIFICATION OF ELEMENTS
Classification of elements: The process of arranging of elements in
different groups and sub groups on the basis of similarities and
dissimilarities of their properties is
called classification of elements.
Triads or Dobernier's triads: A group of three elements which have the
same chemical properties.
Lother Meyers curve: The graph that is plotted between the
atomic volume and the atomic mass of different elements.
Mendeleev’s periodic
table: The table or chart which is made
after arranging elements on the basis of increasing atomic weight or Mendeleev
periodic law.
Mendeleev periodic law: It states that “the physical and the
chemical properties of an element are the periodic function of their atomic
mass.”
Modern periodic law: It states that “the physical and the
chemical properties of an element are the periodic function of their atomic
number.”
Modern periodic table: The table or chart which is made after
arranging elements on the basis of increasing atomic number or Modern periodic
law.
Period: The horizontal row of elements in periodic table is called period.
Group: The vertical column of elements in periodic table is called group.
Periodic table: A table in which elements are classified
into various blocks, periods and groups on the basis of their similarities and
dissimilarities is called periodic table.
Alkali metal: The highly reactive metal of group IA which forms highly strong alkali on reacting with water is called alkali metal.
Eg. Li, Na, K, Rb etc
Alkaline earth metal: The reactive metal of group IIA which form oxide on the earth surface and react with water to produce alkali.
Eg. Be,
Mg, Ca,Ba and Ra.
Halogens: The member of group VIIA which react with hydrogen to form acid from which simple salt can be made is called halogens.
Eg. Cl, Br, I , F
Noble or inert gas: The element of group 0 which do not react with any other elements due to its stable electronic configuration.
Transition elements: The elements of group IB to VIIB and VIII are called transition elements.
Lanthanides: The elements with atomic number 58 to 71 are called
lanthanides.
Actinides: The elements with atomic number 90 to 103 are called actinides.
Ionization potential: The amount of energy required to remove
loosely bounded electrons from the valence shell of an isolated gaseous atom to
form an ion.
Electro negativity: It is the tendency of an atom to attract
electron towards itself when combined in a compound.
Electro-positivity : It is the tendency of an atom to lose
electron when combined in a compound.
S – block elements: The elements of modern
periodic table in which valence electron enters in s orbital.
P – block elements: The elements of modern periodic table in
which valence electron enters in p orbital.
d – block elements: The elements of modern periodic table in
which valence electron enters in d orbital.
f– block elements: The elements of modern periodic table in
which valence electron enters in f orbital.
Electronic configuration: The systematic arrangement of electrons in
various shell is called electronic configuration.
Duplet state: The state of an atom in which outermost
shell of an atom has the capacity to fill only two electrons.
Octet state: The state of an atom in which outermost shell of an atom has
the capacity to fill only eight electrons.
2n2 rule: The rule which determine the maximum
number of electron that can be placed in a shell.
Valence electron: The number of electrons present in the
outer most shell of an atom is called valence electron.
Valency: The combining capacity of an element with other element during
chemical reaction is called valency.
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