Chemistry Quick Guide
Chemistry Quick Guide
Particles of matter are very small, normally, not visible from naked eye.
The attracting force of the particles keeps the particles together; however, the
strength of the attracting force varies from one kind of matter to another.
States of Matter
Solid State
Liquid State
Gaseous State
Solid State
All the solid materials have a definite shape, distinct boundaries, and fixed volumes.
Most of the solid materials have negligible compressibility.
All the solid materials have a natural tendency to maintain their shape when
subjected to outside force.
The solid materials can be broken under applied force, but it is very difficult to
change their shape, as they are rigid.
Liquid State
Unlike solids, liquids have no fixed shape; however, they have a fixed volume.
Liquids take up the shape of the container in which they are kept.
Gaseous State
Matter in the form of air, which is neither solid nor liquid, is known as gas. For
example, oxygen, nitrogen, hydrogen, etc.
Unlike solid, gas has not definite size and shape.
The gases, such as liquefied petroleum gas (LPG used in cooking); compressed
natural gas (CNG used as fuel in vehicles), etc. have high compressibility;
therefore, large volume of a gas can be compressed into a small cylinder and can
be transported easily.
Gases, normally, show the property of diffusing very fast into other gases. This is
the reason that we can smell (either good or bad) from the distance.
Water can exist in all three states, e.g. Ice as solid; water (H2O) as liquid; and
water vapor as gas. The following diagram illustrates the transformation of water in
different states −
The temperature, at which solid melt and transform into the liquid (at the given
atmospheric pressure), is known as melting point.
The melting point of a solid is an indication of the strength of the force of attraction
between its particles.
The melting point of ice is 273.16 K, i.e. 0 0 C.
The process of melting (i.e. change of solid state into liquid state) is known as
fusion.
The temperature at which a liquid starts boiling at the given atmospheric pressure is
known as boiling point.
A change of state of a matter directly from solid to gas without changing into liquid
state (or vice versa) is known as sublimation.
The phenomenon i.e. change of a liquid into vapors at any temperature below its
boiling point is known as evaporation.
Solid CO2 gets converted directly into gaseous state once the pressure decreases
to 1 atmosphere.
Atmosphere (atm) is a unit of measuring pressure exerted by the gas and the unit
of pressure is Pascal (Pa); 1 atmosphere = 1.01 105 Pa.
Plasma is the state that consists of super energetic and super excited particles.
The super excited particles are found in the form of ionized gases. E.g. the
fluorescent tube (which contains helium gas) and neon sign bulbs (which contain
neon gas) consist of plasma.
Mixtures of two or more pure components without any undesirable substance are
known as Mixtures, for example, water, minerals, soil etc.
The particles of a solution are even smaller than 1 nm (10-9 meter) in diameter
and hence, these are not visible from the naked eyes.
The dissolved particles cannot be separated from the mixture by the simple
process of filtration.
Suspension
The particles of a suspension scatter a beam of light that passes through it and
likewise, its path is visible.
The salute particles can be separated from the mixture by the simple process of
filtration.
Colloid
A heterogeneous mixture is known as colloid. E.g. mist, fog, smoke, face cream,
etc.
The size of colloid particles is too small to see from the naked eye.
Colloid particles are big enough to scatter a beam of light passing through it and
make the path visible.
Colloid particles cannot be separated from the mixture by the simple process of
filtration.
The special filtration technique i.e. centrifugation, can be used to separate the
colloidal particles.
Chromatography
Distillation
Crystallization
The process that separates a pure solid in the form of its crystals from a solution is
known as crystallization.
Elements
In 1661, Robert Boyle was the first scientist who used the term element; Antoine
Laurent Lavoisier, a French chemist, was the first who experimentally define the
term element.
Element is as a basic form of matter that cannot be broken down into simpler
substances by a chemical reaction.
Metal
A solid material, which typically is hard, ductile, malleable, shiny, and fusible with
good electrical and thermal conductivity, is known as metal. E.g. gold, silver,
copper, aluminum, etc.
Non-metal
All elements or substances, which are not metals, are known as non-metals. E.g.
hydrogen, oxygen, iodine, carbon, etc.
Non-metals have variety of colors and they are poor conductors of heat and
electricity.
Compound
Around 500 BC, an Indian Philosopher Maharishi Kanad, first time postulated the
concept of indivisible part of matter and named it pramanu.
In 1808, John Dalton used the term atom and postulated the atomic theory to
the study of matter.
According to Daltons atomic theory, all matters, whether they are elements,
compounds, or mixtures, are composed of small particles known as atoms.
All atoms of an element are identical in mass and chemical properties whereas,
atoms of different elements have different masses and chemical properties.
To form a compound, atoms are combined in the ratio of small whole numbers.
In a given compound, the relative number and kinds of atoms are constant.
Atomic Mass
The atomic mass is roughly equivalent to the number of protons and neutrons
present in the atom.
One atomic mass unit is a mass unit equal to the exactly one-twelfth (1/12th) the
mass of one atom of carbon-12 and the relative atomic masses of all elements
have been calculated with respect to an atom of carbon-12.
Molecule
Ion
Chemical Formulae
Molecular Mass
The molecular mass of a substance is calculated by taking the sum of the atomic
masses of all the atoms in a molecule of respective substance. For example, the
molecular mass of water is calculated as −
The water contains two atoms of hydrogen and one atom of oxygen.
The formula unit mass of a substance is calculated by taking the sum of the atomic
masses of all atoms in a formula unit of a compound.
Avogadro was an Italian scientist who had given the concept of Avogadro Number
(also known as Avogadro Constant).
In 1896, Wilhelm Ostwald had introduced the concept of mole; however, mole unit
was accepted to provide a simple way of reporting a large number in 1967.
During a chemical reaction, sum of the masses of the reactants and products
remains unchanged, which is known as the Law of Conservation of Mass.
By 1900, it was discovered that the atom was not a simple, indivisible particle, but
rather it contains sub-atomic particles.
J.J. Thomson was the first person who proposed a model for the structure of an
atom.
Thomson proposed that an atom consists of a positively charged sphere and the
electrons (negative charge) are embedded in it (as shown in the image given
below).
Further, Thomson said that the negative and positive charges are equal in
magnitude. Thus, the atom as a whole is electrically neutral.
Rutherford is largely known for his work on radioactivity and the discovery of the
nucleus of an atom with the gold foil experiment (as shown in the image given
below.
Rutherford said that in an atom, there is a positively charged center known as the
nucleus.
Rutherford said that nearly all the mass of an atom exists in in the nucleus.
Neils Bohr further extended Rutherfords model and improved his drawbacks.
According to Bohr, only certain special orbits known as discrete orbits of electrons,
are allowed inside the atom.
Bohr said that electrons do not radiate energy while revolving in discrete orbits.
Bohr named orbits or shells as energy levels (as shown in the image given below).
Neutron
The maximum number of electrons that can be present in a shell is given by the
formula 2n2.
Electrons are not filled in a given shell, unless the inner shells are filled. It means,
the shells are filled in a step-wise manner; starting from inner shell to outer shell.
Valence
The electrons, those are present in the outermost shell of an atom, are known as
the valence electrons.
Atomic Number
Mass Number
The sum of the total number of protons and neutrons, present in the nucleus of an
atom, is known as mass number.
Isotopes
The atoms of the same element, having the same atomic number but different
mass numbers, is known as isotopes. E.g. Hydrogen atom has three isotopes
namely protium, deuterium, and tritium.
The chemical properties of isotopes of an atom are similar but their physical
properties are different.
Isobars
Atoms of different elements with different atomic numbers, which have the same
mass number, are known as isobars. E.g. calciums atomic number is 20and argons
atomic number is 18; further, the number of electrons in these atoms is different,
but the mass number of both these elements is 40.
A process in which one or more chemical substances react with other chemical
substance and converted to one or more different substances is known as
chemical reaction.
Chemical Equation
The substances magnesium and oxygen are known as reactants and the result of
reaction, i.e., magnesium oxide is known as product.
Remember, the total mass of the elements present in the products of a chemical
reaction has to be equal to the total mass of the elements present in the
reactants.
The number of atoms of each element always remains same, before and after the
chemical reaction.
Combination Reaction
Decomposition Reaction
Displacement Reaction
Combination Reaction
As illustrated in the above reaction, calcium oxide and water reacted (or combined)
to form a single product, known as calcium hydroxide.
The chemical reaction in which heat is also released along with the formation of
product is known as exothermic chemical reactions.
Decomposition Reaction
The reaction, in which a single reactant breaks down into simpler products, is
known as a decomposition reaction. E.g.
In the above given reaction, Ferrous sulphate crystals (i.e. FeSO4, 7H2O), when
heated, it loses water and the color of the crystals changes. Finally, it decomposes
into ferric oxide (Fe2O3), sulphur dioxide (SO2) and sulphur trioxide (SO3).
Displacement Reaction
In the above given reaction, iron displaced copper from copper sulphate solution
and forms Iron sulphate.
In the above given reaction, the copper oxide loses oxygen and hence reduced (i.e.
reduction); on the other hand, hydrogen gains oxygen and hence oxidized (i.e.
oxidation).
Corrosion
Rancidity
When fats and oils are getting oxidized, the process is known as rancidity. Their
smell, taste, color, etc. also change; likewise, it made food unsafe for
consumption.
We taste food sour and bitter, it is only because of presence of acids and bases
respectively.
Litmus Solution
Litmus, which is extracted from lichen, has purple color (see the image given
below), but the condition is when it is neither acidic nor basic, i.e. neutral.
The substances, which odor changes in acidic or basic media, are known as
olfactory indicators.
The hydrogen ions in HCl are produced because of the presence of water. Secondly,
the separation of H+ ion from the HCl molecules cannot be done in the absence of
water. The chemical formula is illustrated below
HCl + H2O → H3O+ + Cl
Furthermore, hydrogen ions cannot exist alone, but they can exist in presence of
water molecules. Therefore, hydrogen ions are shown as H+(aq) or hydronium ion
(H3O+). The chemical formula is −
H+ + H2O → H3O+
The bases which are soluble in water are known as alkalis. But all bases are not
soluble in water.
Mixing an acid or base with the water results into decrease in the concentration of
ions (i.e. H3O+/OH) per unit volume and the process is known as dilution.
pH Scale
pH value is taken simply as a number, which indicates the acidic or basic nature of a
solution. So, if the concentration of hydronium ion is higher, then the value of pH
would be lower.
The value of pH scale ranges between 0 and 14; so, if pH value is measured 0, it
means it is very acidic and if it is 14, then it means it very alkaline.
On a pH scale, values less than 7 represent an acidic solution and values greater
than 7 represent a basic solution.
Usually, paper impregnated with the common indicator is used for measuring the
pH (see the image given below)−
Likewise, the strength of acids and bases substance mainly depends on the number
of H+ ions and OH ions produced, respectively.
The following image roughly illustrates (variations in color) the pH value of some of
the common substances −
The stomach of a human body produces hydrochloric acid that helps in the
digestion of food; surprisingly, it does not harm the stomach anyway.
However, when the stomach produces too much acid (known as indigestion), it
causes pain and irritation. To get relief from this pain, doctors suggest the use of
bases known as antacids.
The teeth, which are made up of calcium phosphate, is the hardest substance in
the body. However, when the pH in the mouth decreases (below 5.5), it corrodes
the teeth.
The salt, normally, is formed by the combination of hydrochloric acid and sodium
hydroxide solution; and, the combination is known as sodium chloride.
When the pH value of rain water is measured as less than 5.6, it is known as acid
rain.
When acid rain flows into the rivers, then it also lowers the pH of the river water
The acidic river water is threat for the survival of aquatic life.
Bleaching Powder
Baking Soda
The baking soda is commonly used in the kitchen in order to cook tasty crispy food
items. It also cooks some food items faster.
Washing Soda
Plaster of Paris
Plaster of Paris is a white powder that doctors use as plaster for supporting
fractured bones.
The chemical name of plaster of paris is calcium sulphate hemihydrate and chemical
formula is 2CaSO4.H2O.
The metals can be distinguished from the non-metals on the basis of their chemical
and physical properties.
The property of metals by which they can be beaten into thin sheets is known as
malleability.
The property of metal by which it can be drawn into wires is known as ductility.
The metals are normally hard, malleable, lustrous, ductile, sonorous, and good
conductors of heat and electricity. E.g. iron, copper, calcium, aluminum,
magnesium, etc.
The materials, which are not sonorous and are poor conductors of heat and
electricity, are known as non-metals. E.g. sulphur, carbon, oxygen, phosphorus,
etc.
Some metals, such as sodium and potassium are soft and can be cut with a
knife.
Mercury is the only metal, which remains in liquid state at room temperature.
On burning, metals easily react with oxygen and produce metal oxides, these are
basic in nature.
Non-metals react with oxygen and produce non- metallic oxides; these are acidic in
nature.
Some metals react with water and produce metal hydroxides and hydrogen gas.
Metals also react with acids and produce hydrogen gas and metal salts.
A solid material, which is typically hard, malleable, shiny, fusible, and ductile, is
known as metals. E.g. iron, copper, aluminum, magnesium, sodium, lead, zinc, etc.
Metals, in their pure state, have a shining surface, known as metallic luster.
Metals can be beaten into thin sheets; this property is known as malleability.
The property of metals to be drawn into the thin wires is known as ductility. E.g.
gold is the most ductile metal.
Non-Metals
The non-metals are normally found in either solids or gases states. However,
bromine is an exception that found in liquid state.
Some of the major examples of non-metals are carbon, sulphur, iodine, oxygen,
hydrogen, etc.
All metals exist in the solid form at room temperature, except mercury.
Gallium and caesium have very low melting points; these two metals get melt even
on palm.
Carbon is a non-metal that can exist in different forms. Each form is called an
allotrope.
Alkali metals, such as lithium, potassium, sodium, are the examples of soft metals,
as they can be cut with a knife.
Nearly all metals when combined with oxygen, it forms metal oxides.
Different metals have different frequency of reaction; some react slow, but some
react very fast. E.g. potassium and sodium are very reactive and they catch fire
only if kept in the open.
Therefore, potassium and sodium are kept immersed in kerosene oil so that they
cannot catch fire.
However, among all metals, sodium (most likely), is the most reactive metal.
The elements or compounds that occur naturally in the crust (upper layer) of the
earth, are known as minerals.
The minerals in raw form is known as ores. E.g. gold, silver, iron etc. (iron ore
shown in the image given below) −
The ores, which are extracted from the earth, are usually contaminated with large
amounts of impurities such as mix with some elements, soil, sand, etc., known as
gangue.
Based on the reactive nature and extraction from the ores, metals can be
categorized as −
The amount of carbon in the earths crust is merely 0.02%, which is available in the
form of minerals such as carbonates, hydrogen-carbonates, coal, and petroleum.
The presence of carbon in the atmosphere of the earth is 0.03%, in the form of
carbon dioxide.
Compounds of Carbon
Almost all carbon compounds (except a few) are poor conductors of the electricity.
The diamond and graphite both are formed by carbon atoms; however, the
difference lies between them in the manner in which the carbon atoms are bonded
to one another.
In diamond, each atom of the carbon, is bonded to four other carbon atoms and
form a rigid three-dimensional structure (see the image given below).
In graphite, each atom of the carbon, is bonded to three other carbon atoms in the
same plane, which gives a hexagonal array (see the image given below) −
Diamond is the hardest substance known whereas graphite is smooth and slippery
substance.
Methane CH4
Ethane C 2H6
Propane C 3H8
Butane C 4H10
Pentane C 5H12
Hexane C 6H14
The compounds, which has identical molecular formula, but different structures, are
known as structural isomers (see the structure Butane given below).
The unsaturated hydrocarbons, which comprise of one or more double bonds, are
known as alkenes.
The unsaturated hydrocarbons, which comprise of one or more triple bonds, are
known as alkynes.
Sugarcane plants very efficient convert sunlight into chemical energy and its juice
can be used to prepare molasses.
These alcohol, on burning in sufficient air (oxygen), gives rise to only carbon
dioxide and water.
Esters
When esters react in the presence of an acid or a base, it gives back the alcohol
and carboxylic acid.
Interestingly, the ionic-end of soap dissolves in water whereas the carbon chain
dissolves in oil. This typical features of the soap molecules forms structures known
as micelles (see the image given below)
In micelles, one end of the molecules is towards the oil droplet whereas the ionic-
end remains outside.
The soap micelle helps in dissolving the dirt in water; likewise, the clothes get
cleaned.
On the other hand, detergents are usually ammonium or sulphonate salts of long
chain carboxylic acids, which remain effective even in hard water.
Detergents are customarily used to make shampoos and some other products for
cleaning clothes.
There are about 115 elements have been known to us till today.
Based on their properties, all the elements are arranged in order, known as periodic
table.
John Newlands, an English scientist, also attempted to arrange the then known
elements (in 1866).
John Newlands had followed the order of increasing atomic masses to arrange the
elements.
Newlands started with the element having the lowest atomic mass (such as
hydrogen) and ended at thorium, which was the 56th element (at his time).
H Li Be B C N O
F Na Mg Al Si P S
Cl K Ca Cr Ti Mn Fe
Co & Ni Cu Zn Y In As Se
Br Rb Sr Ce & La Zr
Newlands also compared it with the octaves that found in music (see the table
given above).
In the Indian music, the seven musical notes are sa, re, ga, ma, pa, da, ni;
however, in the west, the musical notes are do, re, mi, fa, so, la, ti.
Further, in order to fit some elements into his Table, Newlands put two elements in
the same cell (see the table given above cobalt & nickel kept in same cell), but this
technique did not work, as they have different properties.
However, the law of octave had limitation, as was applicable up to calcium only;
and, after calcium every eighth element had not the properties similar to that of
the first.
Mendelev arranged the sequence in inverted fashion so that elements with similar
properties could be grouped together.
Mendelev left space for some elements, which were not discovered at that time;
he boldly predicted about the existence of future elements.
In 1913, Henry Moseley, an English physicist discovered that the atomic number of
an element is a more fundamental property in comparison to its atomic mass.
Based on Moseleys discovery, Mendelevs Periodic Law was modified and atomic
number was adopted as the basis of Modern Periodic Table.
18 vertical columns known as groups and 7 horizontal rows known as periods are
defined in the Modern Periodic Table.
In Modern Periodic Table, the elements are arranged in such a way that it shows
periodicity of properties such as atomic size, valency, or combining capacity and
metallic and non-metallic characteristics (of elements).
In Modern Periodic Table, the metallic character decreases across a period and
increases down the group.
On the other hand, non-metals are electronegative, as they tend to form bonds by
gaining electrons.
In Modern Periodic Table, the non-metals are placed on the right-hand side (from
the top).
The clothes that we wear are made up of fabrics and the fabrics are made from
fibers, which is obtained from natural or artificial sources.
The natural source of fibers is cotton, wool, silk, etc., which are obtained from
plants or animals.
The synthetic fibers are made by human beings; therefore, these are called
synthetic or man-made fibers.
A synthetic fiber is usually a chain of small units those joined together; each small
unit is a chemical substance.
The fiber, prepared from coal, water and air, is known as Nylon.
PET is one of the familiar form of polyesters and it is used for making utensils,
bottles, films, wires, and many other useful products.
There are some plastics, which when molded once, cannot be softened by heating;
therefore, these are known as thermosetting plastics. E.g. Bakelite and melamine.
Melamine resists fire and can tolerate heat better than other plastics; therefore, it
is used for making floor tiles, kitchenware, and fabrics.
A material, which gets decomposed through the natural processes, e.g. action by
bacteria, is known as biodegradable.
The resources, which are present in unlimited quantity in nature and are not likely
to be exhausted by human activities, are known as Inexhaustible Natural
Resources. E.g. sunlight, air.
The resources, which are present in limited quantity in nature and are likely to be
exhausted by human activities, are known as Exhaustible Natural Resources.
E.g. forests, wildlife, minerals, coal, petroleum, natural gas etc.
Exhaustible natural resources were formed from the dead remains of living
organisms (fossils); therefore, these natural resources are also known as fossil
fuels. E.g. coal, petroleum and natural gas.
Coal
Under high pressure and high temperature, the dead plants those got buried inside
the Earth, got slowly converted into coal.
Coal is formed from the remains of vegetation; therefore, it is also known as fossil
fuel.
When coal is processed in industry, it produces some useful products such as coke,
coal tar, and coal gas.
Coke is largely used in the manufacturing of steel and in the extraction of many
metals.
The products, those are obtained from coal tar, are used as starting materials for
manufacturing various substances used in everyday life and in industry. E.g.
explosives, paints, roofing materials, synthetic dyes, drugs, perfumes, plastics,
photographic materials, etc.
Naphthalene balls, obtained from coal tar, are used to repel moths and other
insects.
Chapters Categories
Bitumen, obtained from petroleum product, is used in place of coal-tar for
metalling the roads.
In 1810, for the first time in London, UK, coal gas was used for street lighting and
in 1820, in New York, USA.
Petroleum
Petrol and diesel are obtained from a natural resource known as petroleum.
Over millions of years (the dead organisms buried inside the earth), in the presence
high temperature, high pressure, and in the absence of air, the dead organisms
transformed into petroleum and natural gas.
In 1859, the worlds first oil well was drilled in Pennsylvania, USA.
The different useful substances, which are obtained from the petroleum and natural
gas, are known as Petrochemicals.
Hydrogen gas, which is obtained from natural gas, is used in the production of
fertilizers (urea).
Natural gas is normally stored under high pressure and hence known as
Compressed Natural Gas (CNG).
Petroleum Gas in Liquid form (LPG) Fuel for home and industry
A chemical process in which a substance reacts with oxygen and give off heat is
known as combustion.
During the combustion, light is also given off either in the form of a flame or as a
glow.
There are three different zones of a flame dark zone, luminous zone and non-
luminous zone.
The lowest temperature at which a substance catches fire is known as its ignition
temperature.
The rubbing surface of match contains powdered glass and a little red phosphorus.
When the match stick is struck against the rubbing surface, some red phosphorus
gets converted into white phosphorus; the process immediately reacts with
potassium chlorate present in the matchstick head and produce enough heat to
ignite antimony trisulphide; likewise, combustion starts.
The substances, which have very low ignition temperature and can easily catch fire
with a flame, are known as inflammable substances. E. g. petrol, alcohol,
Liquified Petroleum Gas (LPG), etc.
Fire Extinguisher
Water, as fire extinguisher, works only when things like wood and paper are on fire.
If electrical equipment is on fire, water may conduct electricity and damage those
trying to douse the fire.
Water is also not a good extinguisher for fires involving oil and petrol.
For fires that involve electrical equipment and inflammable materials such as petrol,
Carbon Dioxide (CO2) is the best extinguisher.
One of the ways to get CO2 is to release plenty of dry powder of chemicals such
as sodium bicarbonate (baking soda) or potassium bicarbonate.
The calorific value of a fuel is measured in a unit called kilojoule per kg (kJ/kg).
Wood 17000-22000
Coal 25000-33000
Petrol 45000
Kerosene 45000
Diesel 45000
Methane 50000
CNG 50000
LPG 55000
Biogas 35000-40000
Hydrogen 150000
Increased concentration of carbon dioxide in the air is most likely causes global
warming.
Global warming causes melting of polar glaciers, which leads to a rise in the sea
level that ultimately causing floods in the coastal regions.
Oxides of sulphur and nitrogen dissolve in rain water and form acids; such type of
rain is known as acid rain.
TOP TUTORIALS
Python Tutorial
Java Tutorial
C++ Tutorial
C Programming Tutorial
C# Tutorial
PHP Tutorial
R Tutorial
HTML Tutorial
CSS Tutorial
JavaScript Tutorial
SQL Tutorial
TRENDING TECHNOLOGIES
Git Tutorial
Docker Tutorial
Kubernetes Tutorial
DSA Tutorial
SDLC Tutorial
Unix Tutorial
CERTIFICATIONS
DevOps Certification
Online C Compiler
Online C# Compiler
Tutorials Point is a leading Ed Tech company striving to provide the best learning material on
technical and non-technical subjects.