Friday 17 June 2016
Tuesday 31 May 2016
Definitions
Definitions
Matter is anything that occupies space and has mass
and made up of tiny particles.
ATOM is the smallest particle of a substance or
the fundamental unit of the matter.
Atom may or
may not exist independently.
An atom is
composed of sub-atomic particles called proton,
electrons and Neutrons.
MOLECULE: A molecule is formed when two or more atoms
of same or different kind combine chemically.
ELEMENT: An element
is a pure substance made up of identical atoms.
COMPOUND: Two or more atoms of different kind combine
chemically in a fixed proportion to form a compound.
ATOMICITY: The number of atoms present in a molecule of
an element is called its atomicity.
ATOMIC NUMBER (Z): The number of protons present in the nucleus
of an atom of an element is
called
its Atomic number.
MASS NUMBER (A): The total number of protons and neutrons
present in the nucleus of an atom of
an element.
ELECTRONIC CONFIGURATION: The distribution of electrons in the shells
(or) orbits in atom is
called
electronic configuration.
STABLE ELECTRONIC CONFIGURATION:
If
an element has completely filled valence shell or 8 valence electrons then it
is said to have stable electronic configuration.
OCTET CONFIGURATION: If an element has 8 valence electrons it is
called Octet configuration.
VALENCY:
ELECTRO-VALENCY: The number of electrons that an atom of an
element loses or gains to attain stability is called the electro-valency of
that element.
COVALENCY: The number of electron pairs which an atom
of an element shares with atoms of the same or different kind to attain
stability.
ION: An ion
is an atom or a group of atoms carrying a charge (positive or negative).
Positively
charged ions are termed as Cations and
those which are negatively charged as Anions.
CHEMICAL BOND: The force of attraction by which two or more
atoms of same or different kind are held together is a chemical bond.
ELECTROVALENT BOND: The strong electrostatic force of attraction
that holds two oppositely charged ions together which are formed as a result of
transfer of electron/s.
COVALENT BOND: A covalent bond is formed due to the mutual
sharing of electron pairs between two non-metallic atoms.
CO-ORDINATE COVALENT BOND: It is a covalent bond in which both the
electrons in the bond coming from the same atom.
ATOMIC RADIUS: The distance between the centre of the
nucleus and the valence shell of an atom.
ELECTRONEGATIVITY: The tendency of an element to attract the
bond pair of electrons towards itself .
ELECTRON AFFINITY: The amount of energy released when an atom
accepts an electron to form an anion.
IONISATION POTENTIAL: The minimum amount of energy required to
remove an electron from the valence shell of an atom in gaseous state.
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