Acidity
The
acidity of a base is defined as the number of ionizable hydroxyl groups in its
molecule.
Anode
It is an
electrode through which electrons enter the external circuit.
Alpha
Rays
There are
positively charged particles emitted from a radioactive substance. They carry
two positive charges and are called helium nuclie.
Analytical
Chemistry
It is the
branch of chemistry which discusses the analytical methods forgetting
information about chemical compounds and chemical processes.
Atomic Number
Number of
positively charged particles (protons) present in the nucleus of an atom.
Atomic
Size
Average
distance between the nucleus of an atom and its outermost electronic shell. Its
units are nm or pm.
Arrehenius
Acid
It is a
chemical compound which gives proton (H+) in water.
Arrehenius Base
It is a
chemical compound which gives hydroxide ion (OH-
Atomic
Spectrum
Spectrum
of radiations emitted by the excited atoms when they come to the normal state.
Acidic
Salts
An acidic
salt is obtained when hydrogen atoms present in an acid, are partially replaced
by metallic atoms.
Alchemist
A
scientist trying to convert cheaper metals into precious metals is called
Alchemist and this branch of chemistry is called Alchemy.
Atomic
Mass
The mass of
an element relative to the unit mass, which is 1/12th o the mass of C-12.
Ampere
The
amount of electric current which liberate one electrochemical equivalent of a
substance per second during electrolysis of that substance is called ampere.
Biochemistry
It is the
study of chemical compounds present in living things.
Balancing of Chemical Equations
Equating
the atoms of reactants with those of products.
Beta Rays
These are
electrons emitted from a radioactive substance.
Brownian
movement
The free
movement of the molecules of gases and liquids is called Brownian movement.
Bronsted
Acid
A
compound which can donate proton.
Bronsted
Base
A
compound which can accept proton.
Basicity
The
basicity of an acid is defined as the number, of ionizable hydrogen atoms
present in its molecule.
Basic
Salts
A basic
salt is obtained when the hydroxyl groups present in a base are partially
replaced by some other groups.
Boiling
Point
A
temperature at which a liquid changes into gaseous state.
Chemistry
The
branch of science, which deals with the composition of matter changes in matter
and the laws or principles which govern these changes.
Chemical
Equation
The
representation of a chemical change in terms of symbols and formulas.
Covalent
Solid
A solid
in which there exist a covalent bond between atoms.
Covalent
Bond
It is the
force of attraction that arises between two atoms due to mutual sharing of an
electron pair.
Co-Ordinate
Covalent Bond
When the
shared pair of electrons is provided by one of the bonded atoms, a coordinate
covalent bond is formed.
Cohesive
Forces
The
forces of attraction present between the particles of solid, liquid and a gas.
Cathode
Rays
Rays
emitted from cathode in the discharge tube.
Colloidal
Solution
A
solution in which solute particles are bigger than those present in a true
solution and which cannot be filtered.
Conductor
A
substance which allows electric current to pass through it.
Cathode
It is an
electrode through which electrons leave the external circuit.
Concentration
of a Solution
The
amount of a solute which has been dissolved in a particular amount of a
solvent.
Concentrated
Solution
A
solution, which contains an excess amount of a solute as compared to that of a
solvent.
Cell
The
vessel containing reacting substances in which transfer of electrons takes
place is called cell.
Coulomb
It is
unit of electric current. When one ampere electric current is passed for one
second the quantity of electric current is one coulomb.
Discharge
Tube
A glass
tube containing a gas at a very low pressure and provided with electrodes to
study the passage of electricity through the gas.
Dipole-Dipole
Forces
The
forces of attraction which originate due to the difference in electro
negativities of the bonded atoms in polar molecules.
Diffusion
The
movement of molecules from a higher concentration to a Lowr concentration is
called Diffusion.
Dilute
Solution
A
solution, which contains a small amount of a solute as compared to that of a
solvent.
Double
Salts
When two
typical salts are crystallized together a double salt is formed. The physical
properties of the crystals of double salt are different from those of the
component salts.
Doberiner’s
Law of Triads
Dobereiner
arranged similar elements in sets of three, called Triads. Atomic mass of the
middle atom of a triad was equal to the average of the atomic masses of first
and third members.
Degree of
Ionization
It is the
extent to which an electrolyte ionizes in water.
Experiment
An
experiment is an activity performed under suitable conditions with specially
designed instruments to get the required information.
Empirical
Formula
The
formula of a compound which shows the minimum ratio present between the atoms.
Electron
Affinity
The
amount of energy given out when an electron is absorbed in the outermost
electronic shell of all isolated gaseous atom. Its units are KJ/mol.
Electro-Negativity
It is the
power of an atom to attract the shared pair of electrons.
Evaporation
The
continuous escape of the molecules of a liquid from its surface.
Elastic
Collision
When gas
molecule collides with each other their total energy does not decrease or
increase. This type of collision is called an elastic collision.
Electrolytic-Cell
In a
non-spontaneous oxidation-reduction reaction takes place with the help of
electrical energy.
Electro-Chemistry
It is
that branch of chemistry in which chemical energy is converted into electrical
energy or electrical energy is converted into chemical energy.
Electrolytes
When
electricity is passed through an ionic compound which is either in the fused
state or in the form of aqueous solution, it is decomposed into its
constituents. The ionic compound is called an electrolyte.
Electrolysis
The
passage of electricity through an electrolyte is called electrolysis.
Electrochemical
Series
A list of
ions in which they are arranged in the order of their ability to get
discharged.
Electroplating
The
process of depositing a metal on another metal with the help of electricity.
Exothermic
Reaction
Those
chemical reactions during which heat is evolved.
Endothermic
Reactions
Those
chemical reactions in which heat energy is absorbed.
Enthalpy
of Reaction
Heat of
reaction which takes place at constant pressure.
Formula
Mass
Formula
mass is the mass of compound relative to the unit mass which is 1/12th of the
mass of C-12.
Farad
It is the
unit of charge 1 farad = 96500 coulomb.
Fusion
When a
solid change into liquid this phenomena is called Fusion.
Heat of
Neutralization
The heat
given out during a neutralization reaction is called heat of neutralization.
Heat of
Reaction
Heat
evolved or absorbed during a chemical reaction which takes place at pressure.
Hypothesis
In the
light of experiments, the scientists try to explain observations and facts.
This tentative explanation is called hypothesis. It is quite possible that
after sometime, on the basis of new experiments this hypothesis may be
rejected.
Hydrogen
Bonding
When a
hydrogen atom is attached to any one of fluorine, oxygen and nitrogen atoms,
there appears strong dipole forces which are called hydrogen bonding.
Hydrated
Ions
Ions of a
solute surrounded by water molecules are called hydrated ions.
Ionization
An
electrolyte splits up into charged particles upon heating or in its aqueous
solution. This process is called Ionization.
Ionic
Theory
A theory
which explains the process of electrolysis.
Intermolecular
Forces
The
forces of attraction present between the molecules of a compound.
Ionization
Energy
The
minimum amount of energy required to remove an electron from the outermost
electronic shell of an isolated gaseous atom. Its unit is KJ/mol.
Ionic
Bond
A bond
formed due to the electrostatic force of attraction between oppositely charged
ions.
Ionic
Solid
A solid
which is made up of ions of opposite charges.
Isotope
Atoms of
an element having the same atomic number but different mass number.
Inorganic
Chemistry
The study
of all elements and their compounds except carbon is called inorganic
chemistry.
Industrial
Chemistry
The
application of chemical knowledge in technology and industry and the
preparation of industrial products are called industrial chemistry.
Inference
To deduce
results after coordinating the observed facts with integrated scientific
knowledge is called inference.
Kinetic
Theory
The
theory which explains the composition and properties of all the three states of
matter.
Lewis
Acid
A
substance which can accept an electron pair.
Law
A theory
when repeatedly gives the same results after experimentation and offers correct
explanation of scientific facts it then becomes a law or principle.
Law of
Conservation of Mass
Total
mass of reactants is equal to that of products during a chemical reaction.
Law of
Definite
A
compound always contains elements combined together in a fixed ratio by mass.
Law
Multiple Proportions
When two
elements combine together to give more then one compounds, the different masses
of an element, which combine with the fixed mass of the other element, have a
simple ratio between them.
Law of
Reciprocal Proportions
When two
or more elements A and B combine separately with the fixed mass of the third
element E the ratio in which they do so may be the same or some simple multiple
of the ratio in which these two elements (A and B) combine with each other.
Molar
Solution
A
solution in which one mole of a solute has been dissolved in one dm3 of
solution. It is represented as M.
Metallic
Bond
When
positively charged metal ions are held together by freely moving electrons, the
bond formed is called a metallic bond.
Molecular
Solid
A solid
which has Vander Waal’s forces present between its molecules.
Melting
Point
A
temperature at which a solid changes into a liquid.
Mass
Number
The total
number of protons and neutrons present in the nucleus of an atom.
Mendeleyv’s
Periodic Law
Properties
of elements are a periodic function of their atomic masses.
Modern
Periodic Law
Properties
of elements are a periodic function of their atomic numbers.
Molecular
Mass
Molecular
mass is the mass of an element or a compound relative to the unit mass, which
is 1/12th of the mass of C-12.
Molar
Mass
The mass
of an element or a compound which contains Avogadro’s number particles.
Molecular
Formula
The
formula of an element or a compound which tells the actual number of atoms
present in the molecule of that element or a compound.
Neutralization
Acids and
bases react together to form salts and water and in this way they neutralize
the properties of each other. This reaction is called Neutralization reaction.
Normal
Salts
Salts,
which neither have replaceable hydrogen atoms nor hydroxyl groups.
Non-Conductor
A
substance through which electric current cannot pass.
Neutron
It is the
smallest neutral particle present in the nucleus of atoms. Its mass is slightly
more than that of a proton.
Nucleus
Central
part of an atom where most of its mass is concentrated. Its size is very small
as compared to the size of the atom.
Newland’s
Law of Octaves
If
elements are arranged in the increasing order of their atomic masses every 8th
element repeats the properties of the 1st element.
Oxidation
A
chemical reaction in which oxygen is added or hydrogen is removed or electrons
are lost.
Octet
Rule
When an
atom has eight electrons in its outer most shell, its is said to be stable and
does not combine with other atom to reduce its energy. This is called octet
rule.
Organic
Chemistry
The
branch of chemistry in which we study the compounds of carbon.
Observation
The
process of observing natural phenomena with the help of five senses and the
scientific equipment.
Orbits
The circular
path of an electron around the nucleus.
pH Scale
The
negative log of hydrogen ion (H+) concentration present in a solution is called
pH. This scale measures the concentration of hydrogen ions present in a
solution.
Percentage
by Mass
Volume of
a solute present in 100cm3 of a solution.
Percentage
by Volume
Volume of
a solute present in 100 cm3 of a solution.
Physical
Chemistry
The
branch of chemistry, which deals with the physical properties and physical
behaviour of material things.
Prediction
The
inference based on observed facts.
Proton
It is the
smallest positively charged particle present in all kind of atoms. The mass of
this particle is equal to the mass of the hydrogen nucleus (H+).
Positive
Rays
Rays
produced in the discharge tube, which are traveling in a direction opoposite to
the cathode rays.
Reversible
Reaction
Chemical
reaction, which takes place both directions, forward as well as backward.
Reduction
A
chemical reaction in which hydrogen is added or oxygen is removal or electrons
are absorbed.
Radioactive
Rays
Rays
emitted from radioactive element or their compounds, which can cause fogging of
the photographic plate.
Strong
Acid
An acid
which ionizes completely in water.
Strong
Base
A base
which can ionize completely in water giving excess of hydroxide ions.
Sublimation
Some
solids, upon heating, change directly into vapors instead of changing into
liquid.
Scientific
Method
The
method which helps to collect facts on the basis of observations and
experiments. Theories and laws are then formulated to explain these facts.
Solute
The
substance present in relatively lesser amount in a solution.
Solvent
The
substance present in excessive amount in a solution.
Solvated
Ions
Ions of a
solute surrounded by solvent molecules in a solution are called solvated ion.
Saturated
Solution
A
solution, which contains the maximum amount of a solute at a particular
temperature and which is unable to dissolve further amount of solute in it.
Supersaturated
Solution
A
solution which contains an amount of solute more than that required for the
preparation of a saturated solution at a particular temperature.
Standard
Solution
A
solution whose concentration is known.
Solubility
The
amount o solute in grams which can dissolve in 100 gm of solvent at a
particular temperature to give a saturated solution.
Suspension
A mixture
in which solute particles do not dissolve in solvent.
Strong
Electrolytes
An
electrolyte which completely ionize in water.
Transition
Elements
Elements
having incomplete penultimate (next inner to the outermost) electronic shell.
Theory
If a
hypothesis is accepted (after discussion and experimentation) it is called a
theory.
Thermo
Chemistry
It is the
branch of chemistry in which we study the heat changes during a chemical reaction.
Unsaturated
Solution
A
solution, which can dissolve further amount of a solute at a particular
temperature, is called unsaturated solution.
Unified
Atomic Mass Unit
Unit of a
new scale, which is equal to 1/12th of the mass of C-12.
Voltaic
Cell
In a cell
a spontaneous oxidation-reduction reaction is used to produce electric current.
Weak
Electrolyte
An
electrolyte which undergoes partial ionization in water.
Weak Base
A base
which ionizes partially in water.
Weak Acid
An acid
which ionizes partially in water.
Water of
Crystallization
The
number of water molecules present in the crystals of a solid.
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