Some basic concept of Chemistry - 3 for dmlt and paramedical student

              Properties of Matter 

                  The properties of matter are as follows:

(i) Mass and weight:
       Mass represents the amount of substance present in a system, while

      weight represents the force due to gravity exerted on that system.

Weight (W) = mass(m) x gravity(g)

(ii) Volume:
              It is the quantity of three-dimensional space enclosed by a matter.
                   Volume of different bodies are calculated differently,
e.g. for cuboidal body,

Volume (V) = length (1) x breadth (b) x height (h)

for a spherical body.
                . '. Volume =(4/3) π r3

(iii) Density:
        Density is defined as mass per unit volume.
It gives us an idea that how denser or rarer a matter is packed.
   Density (d) = mass (m)/volume (V)

(iv) Temperature :
                   Temperature of a body is the intensity of heat associated with it.

SI and NON-SI UNITS:

The metric system of measurement, the International system of units (SI Units), is widely used for quantitative measurements of matter in science and in most countries.
        However, different systems of measurement existed before the SI system was introduced.

       Any units used in other system of measurement (i.e. not included in the SI system of measurement), will be referred to as non-SI units.
In most science courses, non-SI Units are not be used regularly.

Introduction Non-SI units existed long before the invention of SI units. However, these units have been replaced by the standard SI Units in most countries.

 The countries that have continued to use non-SI units, such as the United States, keep these units mainly for economic, business, and cultural reasons. The following table will introduce some of the commonly used non-SI units, as well as their SI counterparts:

Introduction of Carbohydrates and functions - 1 in kannada medium for dmlt and paramedical students

Carbohydrates – Definition and Functions

Definition of Carbohydrates:

Carbohydrates are defined as polyhydroxy aldehydes or polyhydroxy ketones and the substances which yield these derivatives on hydrolysis.

Functions of Carbohydrates:

i) Supply energy
ii) Stored energy for future use
iii) Structural constituents
iv) Proteins sparing action
v) Necessary for oxidation of protein and fat
vi) Necessary for synthesis of nonessential amino acids
vii) Conserve water and electrolyte
viii) Beneficial effect on micro flora.

Some basic concept of Chemistry notes - 2

LAW OF CHEMICAL COMBINATIONS:

1)Law of Conservation of Mass:

It states that "matter can neither be created nor destroyed".

2)Law of Definite Proportions:

 It stated that "a given compound always contains exactly the same proportion of elements by weight".

Example : Oxygen and hydrogen in water always bear ratio of 16:2 or 8:1 by mass.

3)Law of Multiple Proportions:

According to this law, "if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in the ratio of small whole numbers".

Example

Hydrogen + Oxygen — Water
2g                       16g            18g 

Hydrogen + Oxygen — Hydrogen Peroxide
  2g                      32g                 34g

Here, the masses of oxygen (i.e. 16 g and 32 g) which combine with a fixed mass of hydrogen (2g) bear a simple ratio, i.e. 16:32 or 1: 2.

4)Gay Lussac's Law of Gaseous Volumes:

when gases combine or are produced in a chemical reaction they do so in a simple ratio by volume provided all gases are at same temperature and pressure.

Example:
Hydrogen + Oxygen — Water
  100 mL          50 mL      100 mL

Thus,
the volumes of hydrogen and oxygen which combine together (i.e. 100 mL and 50 mL) bear a simple ratio of 2:1

5)Avogadro Law:

Avogadro proposed that equal volumes of gases at the same temperature and pressure should contain equal number of molecules.

Example .
Hydrogen + Oxygen — Water

we see that two volumes of hydrogen combine with one volume of oxygen to give two volumes of water without leaving any unreacted oxygen.


DALTON'S ATOMIC THEORY:

1. Matter consists of indivisible atoms.
2. All the atoms of a given element have identical properties including identical mass. Atoms of different elements differ in mass.

3. Compounds are formed when atoms of different elements combine in a fixed ratio.

4. Chemical reactions involve reorganization of atoms. These are neither created nor destroyed in a chemical reaction.

5.Dalton's theory could explain the laws of chemical combination.

Some basic concept of Chemistry notes - 1 for dmlt and paramedical students

What is chemistry ?

Chemistry is the science of molecules and their transformations. Chemistry is called the science of atoms and molecules.
Chemistry is the branch of science that studies the composition, properties and interaction of matter.

what is the importance of chemistry?

(1) Chemistry plays an important role in meeting human needs for food, health care products and other materials
(2) Production of a variety of fertilizers, improved varieties of pesticides and insecticides
(3) Preparation of drugs isolated from plant and animal sources or prepared by synthetic methods.
(4) Design and synthesize new materials having specific magnetic, electric and optical properties.
(5) Production of superconducting ceramics, conducting polymers, optical fibres and large scale miniaturization of solid state devices.

What is matter ? 
Anything which has mass and occupies space is called matter.

 for example, book, pen, pencil, water, air, all living beings etc. are composed of matter.

Classification of matter: 

The matter can exist in three physical states viz. solid, liquid and gas.

Solid : Solids have definite volume and definite shape. Reason In solids, these particles are held very close to each other in an orderly fashion and there is not much freedom of movement.

Liquid Liquids have definite volume but not the definite shape. They take the shape of the container in which they are placed.
Reason In liquids, the particles are close to each other but they can move around

Gas: Gases have neither definite volume nor definite shape. They completely occupy the container in which they are placed.

Reason :in gases, the particles are far apart as compared to those present in solid or liquid states and their movement is easy and fast.

Matter can be classified based on chemical state. 

Mixture : A mixture contains two or more substances present in it (in any ratio) which are called its components.

 For example, sugar solution in water, air, tea etc.

Mixtures are two types:

homogeneous mixtures :

 the components completely mix with each other and its composition is uniform throughout.

Examples Sugar solution, air 

heterogeneous mixtures: 

the composition is not uniform throughout and sometimes the different components can be observed.

Example: mixtures of salt and sugar

Pure substances: They have fixed composition . constituents components of pure substances cannot be separated by simple

physical methods. 

Examples Copper, silver, gold, water, glucose etc 

Pure substances can be further classified into 

                         elements and compounds 

Elements: 

An element consists of only one type of particles. These particles may be atoms or molecules. Examples: Sodium, copper, silver, hydrogen, oxygen etc. 

Compound: 

When two or more atoms of different elements combine, the molecule of a compound is obtained.

the properties of a compound are different from those of its constituent elements. 

Constituent particles can be separated by chemical methods. 

The examples of some compounds are water, ammonia, carbon dioxide, sugar etc 

What are the physical properties of the matter? 

Physical properties are those properties which can be measured or observed without changing the identity or the composition of the substance. 

Examples: colour, odour, melting point,boiling point, density etc.

What are the chemical properties? 

The chemical properties are those properties which require a chemical changes to occurs. 

Examples: acidity or basicity, combustability.

                  To be Continue.... 

Preparation of Hydrogen peroxide by laboratory method in kannada medium for dmlt and

Hydrogen peroxide is prepared from barium peroxide by the Laboratory methods:

Barium Peroxide is mixed with ice cold of sulphuric to form Barium sulfate and dilute solution of hydroHyd peroxide

BaO2+H2SO4 ----------> BaSO4+H2O2

More information click 

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Manufacture of nitric acid by ostwald's process and video clip in kannada medium

Manufacturing of nitric acid by Ostwald process

Step 1 — Primary oxidation (formation of nitric acid)

Oxidation of ammonia is carried out in a catalyst chamber in which ammonia and oxygen 1:8 by volume are introduced. The temperature of chamber is about 700'C. This chamber contains a platinum gauze which serves as catalyst.

Oxidization of ammonia is reversible and exothermic process. ammonia is converted into nitric oxide (NO).

4NH3 + 5O2 - - - >4NO + 6H2O 

Step 2 — Secondary oxidation (formation of nitrogen dioxide)

Nitric oxide gas obtained by the oxidation of ammonia is very hot. In order to reduce its temperature, it is passed through a heat exchanger where the temperature of nitric oxide is reduces to 200'C. Nitric oxide after cooling is transferred to another oxidizing tower where at about 50'C it is oxidized to nitrogen dioxide (NO2).

2NO + O2 ----> 2 NO2

Step 3 — Absorption of NO2 (formation of HNO3)

Nitrogen dioxide from secondary oxidation chamber is introduced into a special absorption tower. NO2 gas passed through the tower and water is showered over it. By the absorption, nitric acid is obtained.

3NO2 + H2O - - - -> 2HNO3 + NO

Nitric acid so obtain is very dilute. It is recycled in absorption tower so that more and more NO2 get absorbed. HNO3 after recycle becomes about 68 per cent concentrated.

Step 4 — Concentration:

In order to increase the concentration of HNO3, vapors of HNO3 are passed over concentrated H2SO4. Being a dehydrating agent, H2SO4 absorbs water from HNO3 and concentrated HNO3 is obtained.

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Electrochemistry- Electrolytes and Non electrolytes

Electrolytes and Non-electrolytes:

Electrolytes: 

1)Electrolytes are chemical compounds that can break down into ions when dissolved in water.

2)Electrolytes can conduct electricity through their aqueous solutions.

3)Electrolytes are composed of ionic bonds.

4)Electrolytes are ionic compounds. Acids, base and salts are electrolytes.

5)Electrolytes can be found as strong electrolytes and weak electrolytes.

Non-electrolytes:

1)Nonelectrolytes are chemical compounds whose aqueous solutions cannot conduct electricity through the solution.

2)Nonelectrolytes cannot conduct electricity through their aqueous solutions.

3)Nonelectrolytes are composed of covalent bonds.

4)Nonelectrolytes are covalent compounds. Carbon-containing compounds, fat and sugar are nonelectrolytes.

5)Nonelectrolytes cannot be found as water-soluble compounds and water-insoluble compounds.

Lowry and Bronsted  concept of acids and  bases:

• According to Brønsted-Lowry theory acid is a proton (hydrogen ion) donor.
• According to Brønsted-Lowry theory base is a proton (hydrogen ion) acceptor.

For exmapl, consider the following chemical equation:

HCl(aq)+NH3(aq)---->NH+4(aq)+Cl−

Here, hydrochloric acid (HCl) "donates" a proton (H+) to ammonia (NH3) which "accepts" it , forming a positively charged ammonium ion (NH4+) and a negatively charged chloride ion (Cl-).

 Therefore, HCl is a Brønsted-Lowry acid (donates a proton) while the ammonia is a Brønsted-Lowry base (accepts a proton). Also, Cl- is called the conjugate base of the acid HCl and NH4+ is called the conjugate acid of the base NH3.

 Arrhenius theory of electrolytic dissociation (Ionic theory):

Postulates of the theory are : 

1) When an electrolyte is dissolved in water, its molecules spontaneously split into positively and negatively charged particles called ions. This process is called `dissociation or 'ionisation'. 

2) In a solution, the total positive charges on all the cations (+ve ions) and negative charges on all the anions (--ve ions) are exactly equal. Hence, the whole solution is electrically neutral. 

3) Ions are responsible for the passage of electric current through electrolytes.

4) Ionisation is a reversible process

5) The degree of ionisation of an electrolyte increases with dilution.

6) The properties of electrolytes are the properties of ions present in them.

 Evidences (merits) for Arrhenius theory:

 1) The theory satisfactorily explains the phenomenon of electrolysis and Faraday's laws of electrolysis.

2) Experimental observation shows that the conductance of a solution increases upon dilution. This is in agreement with the theory as more ions are formed during dilution.

3) The solutions of copper sulphate, cupric nitrate, cupric chloride are all blue because they all contain Cu2+ ions. This confirms that properties of electrolytes are properties of ions present in them.

4) Silver nitrate solution reacts with solutions of sodium chloride, potassium chloride, barium chloride etc. to develop a curdy white precipitate. This is possible because all these solutions contain chloride ions which combine with Ag+ ions of silver nitrate. 

        Ag+ + Cl-    - - - - - - - - >  Agcl

5) Ionic theory explains the constancy in enthalpy of neutralisation of any strong acid with any strong base.

6) Arrhenius theory explains the abnormality in the colligative properties (Eg.: osmotic pressure, elevation in boiling point etc.

Limitations (demerits) of Arrhenius theory:

1) The x-ray analysis of crystals like sodium chloride shows the existence of ions even in the solid state. Ions are also present in the molten state. However, according to the theory, ions are formed only in solution. 

2)The theory does not explain why ionisation takes place at all when an electrolyte is dissolved in water.

3)This theory not explain where the required energy for ionisation comes from.

4)The theory does not explain distinguish between the two types of electrolytes.

pH of a solution:

It is defined as 'negative logarithm to the base ten of molar concentration of hydrogen ions in the solution'. 

 pH = - log [H+]

pOH of a solution:

pOH of a solution is defined as 'negative logarithm to the base ten of molar concentration of hydroxyl ions in a solution'. 


pOH= - log[OH-]

pH scale: 

pH of a solution varies between 0 and 14. For neutral solution, pH is 7. For acidic solution, pH is between 0 and 7. For basic solution, pH is between 7 and 14. 

X-ray production and their applications IN KANNADA MEDIUM VIDEO FOR DMLT AND PARAMEDICAL STUDENTS

What is X-ray...??
X-rays are a very energetic form of electromagnetic radiation that can be used to take images of the human body.

X-rays also have these properties:

• they have a very short wavelength (about the same size as the diameter of an atom.
• they cause ionisation (adding or removing electrons in atoms and molecules)
• they affect photographic film in the same way as visible light (turning it black)
• they are absorbed (stopped) by metal and bone.

X-Ray Production:

X-rays are produced due to sudden deceleration of fast-moving electrons when they collide and interact with the target anode. In this process of deceleration, more than 99% of the electron energy is converted into heat and less than 1% of energy is converted into x-rays.

X-rays are produced when electrons strike a metal target. The electrons are liberated from the heated filament and accelerated by a high voltage towards the metal target. The X-rays are produced when the electrons collide with the atoms and nuclei of the metal target.

Applications of X-Rays:

1)X-rays are used in industrial, medical, pure science research and X-ray crystallography etc.

2)X-rays are used to detect defects in radio valves. 

3) X-rays are used to detect cracks in structures. 

4)X-rays are used to analyses the structures of alloys and other composite bodies by diffraction of X-rays.

5) They are also used to study are structure of materials like rubber, cellulose, plastic, fibres etc.

6) X-rays can destroy abnormal internal tissues. 

7)X-rays are used in analysis of crystal structure and structure of complex organic molecule. 

8)They are also used in determining the atomic number and identification of various chemical elements. 

9)X-rays are used to detect fractures and formation of stones in human body. 

10)They are also being used for tumor treatment and for this purpose hard X-rays are used. 

11) X-rays are also used in X-ray crystallography for Laue method, Rotating crystal method, Powder method, etc.

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Video of Preparation of nitric acid by ostwald's process in kannada medium for dmlt and paramedical students

The Nitric acid is manufactured by Ostwald's process

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Colliods and their applications for dmlt and paramedical students

Colliods and crystalloids.

Colloidal: -
            A colloidal is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called   dispersion medium.
Colloidal particles are larger than simple molecules but smaller enough to remains suspended .their range of diameter is between 1and 1000nm (10-9 to 10-6m).
Classification of collides: -
    
a) Lyophillic colloids: -
                             The word ‘lyophillic’ means liquid loving. Colloidal sols directly formed by mixing substances like gum, gelatine, starch, rubber etc. With a suitable liquid (dispersion medium) are called lyophillic sol. These sols are also called reversible sols.

b)Lyophobic Colloids: -
                                   These words ‘Lyophobic’ means liquid hating substance like metals their sulphides etc. When simply mixed with the dispersion medium do not form the colloidal sol. Their colloidal sols can be prepared by only special methods; such sols are called lyophobic sols. These sols are also called irreversible sols.
Preparation of colliods:

a)Electrical disintegration or Bredig’s Arc Method: -
this process involves dispersion well as condensation. Colloidal sol of metals such as gold silver etc can be prepared by this method. in this method electric arc is struck between electrodes of metal immersed in the dispersion medium the intense heat product vaporized the metal, which then condenses to form particles of colloidal size.

c) Peptization: -
                      it is defined as the “process of converting a precipitate into colloidal sol” by shaking it with dispersion medium in the presence of a small amount of electrolyte. The electrolyte used for this purpose is called peptizing agent.
During peptization: - the particulate absorbs the one of the ions of the electrolyte on its surface. This cause the development of +ve charge on precipitate, which ultimately break up into small particles of the size of a colloid.

Purification of colloidal Solution: - 
 The process used for reducing the amount of impurities to a requisite minimum is known as purification of colloidal solution.
it is carried out by following methods
(I) Dialysis: -
              It is a process of removing a dissolved substance from a colloidal solution by means of diffusion through a suitable membrane. Since, particles (ions or smaller molecular) in a true solution can pass through an animal membrane (bladder) or parchment paper or colloidal particles. The molecules and ions diffuse through membrane into the outer water and pure colloidal solution to left behind.

(II) Electro dialysis: -
                                          The process of dialysis is quite slow it can be made faster by applying an electric field electrodes are fitted in the compartment. The ions present in the colloidal solution migrate out to the oppositely charge to electrodes.


Properties of colloidal solutions:
(I)   Colligative Properties: -
The values of colligative properties (osmotic pressure, lowering in vapor pressure, depression in freezing point, elevation in boiling point) are of small order as compared to values shown by true solution at same concentration.
(II)  Colour: -
                           The colour of the colloidal solution depends on the wavelength of the light scatter by the dispersed particles. The wavelength of light further depends on the size and nature of the particles.
(III) Brownian Movement: -
                                                It may be defined as continuous zigzag movement of the colloidal particles in a colloidal solution is known as Brownian movement.

(Iv) Tyndall effect: -
                                        It is may be defending as the scattering of the light by the colloidal particles present in the colloidal solution.
Application of colloids: -
   colloids are widely used in the industrial sector.
Example:-
· Electro precipitation of smoke: -
                     The smoke, before is comes out from the chimney, is led through a chamber containing plates having a charged opposite to that carried by smoke particles. The particles on coming in contact with these plates lose their charge get precipitated, the particles thus settle down on the floor of the chamber. The precipitator is called Cottrell precipitator.

Purification drinking water: -
       alum is added to water (that contain impurities) to coagulate the suspended impurities make water fit for colloidal in nature.
Example: - Argyrol is silver sol is used as an eye lotion.


· Medicines :-
     Most of the medicines are colloidal in nature Ex:- Argirol is a silver sol used as an eye lotion.

Carbohydrates - Classification and examples In kannada medium for DMLT AND Paramedical students

Classification, Structure of Carbohydrates

Classification of Carbohydrates:

Carbohydrates are classified in to three major classes on the basis of complexity and behavior on hydrolysis.
1) Mono saccharides
2) Oligosaccharides
3) Polysaccharides

Hydrocarbons part-1

Hydrocarbons are the organic compounds which contains only C and H.

Methods of preparation:

a) Methane is Prepared in the laboratory by heating a mixture of fused anhydrous sodium acetate and soda lime in a hard glass test tube, The methane liberated is collected over water.
 CH3COONa +NaOH - - -) Na2CO3 +CH4

 b) Pure methane is obtained in the laboratory by the action of zinc- copper couple and alcohol on methyl iodide. Reduction takes place and methane is liberated.

CH3I+ 2[H]---)  CH4 + HI

 Zinc - copper couple is placed in a flask fitted with a stopper carrying a dropping funnel and a delivery tube.
A mixture of methyl iodide and 95% ethyl alcohol is dropped on the zinc copper couple. Methane is liberated. This gas contains methyl iodide vapours as impurity.
So the gas is passed through a U - tube containing zinc - copper couple which converts any methyl iodide in to methane. The methane is collected over water.

Physical Properties:
1.At room temperature and standard pressure, methane is a colorless, odorless gas.
2.Methane is lighter than air, 
3.having a specific gravity of 0.554. 
4.It is only slightly soluble in water.

Chemical properties:

Uses:
 Domestic and industrial fuel.
 Shoe polish.
 Printing ink.
 Tyre manufacturing. 
 Manufacture of methyl alcohol.

Ethene or ethylene 

1)It is the first member of the unsaturated aliphatic hydrocarbon series, and has a double bond.
2)Its molecular weight is 28.
3)Ethene occurs in nature in free state in small quantities in plants.
4)ethene is found in various sources such as natural gas and coal gas.

Preparation of ethene:
In the laboratory ethene is prepared by dehydration of ethanol. On heating ethyl alcohol with sulphuric acid at a temperature of 170 ° C temperature forms ethene.

Cracking or Dehydrogenation:

When alkanes of high molecular weight are heated at high temperature, the molecules breaks into alkane and alkenes of low molecular weight. This process is called cracking.
Ethane when heated upto 500°C forms ethene.

Physical properties:

Ethene is a colourless gas.
Ethene posses pleasant odour at STP.
Ethene is completely soluble in organic solvents and slightly soluble in water.
It is lighter than air.
Boiling point of ethene is -102 ° C and melting point is: –169° C.

Chemical properties :
   

Uses
It has anaesthetic effect on inhalation.
To ripen green fruits

An essential ingredient in manufacture of synthetic chemicals such as ethylene glycol, diethyl ether, ethylene oxide and mustard gas

To manufacture polymers like poly ethylene and poly vinyl chloride

It is also useful in the synthesis of important chemicals useful in industries.


Ethyne (acetylene)

It is generally prepared in a laboratory by the action of water on calcium carbide.

Procedure:

A thin layer of sand is spread atomic the bottom of a conical flask.

A few small pieces of calcium carbide (CaC2) are placed over the sand.
The whole apparatus is set upon.

Water is added to the flask drop wise with the help of a thistle funnel.

Ethyne (acetylene) gas so produced is collected in a gas jar by the downward displacement of water.

Physical properties:

Ethyne is a colourless gas with a characteristic smell. 
It is significantly soluble in water. However readily soluble in organic solvents. 
It is used in welding to produce oxy-acetylene flame of temperature about 3000°C

Chemical properties:

Contiued in part - 2

Modern Periodic Table

Classification and Development of Elements:

Dobereiner's Law of Triads( in 1829):

"All the three elements are arranged" It suggested a relationship between the properties of elements and their atomic weights. 
According to Dobereiner, the atomic weight of the middle element is nearly the same as average of the atomic weights of other two elements. 

Newlands Law of Octaves(1864) :

In 1864, Newlands made an attempt to classify elements. There are seven musical notes in music. 
Every eighth note is similar to the first one and it is the first note of the next scale. Similarly Newland stated that the eighth element starting from a given one is a kind of repetition of the first like the eight notes of an octave of music. So he called this relation ship as the Law of octaves.

According to Newlands' law of octaves when the elements are arranged in order of increasing atomic weights then every eighth element has properties similar to that of the first element. 

Mendeleev's law(1913):

stated the famous periodic law according to which "Properties of elements are a periodic function of their atomic weight".

Mendeleev arranged elements in the order of their increasing atomic weights in the form of a table, which is known as Mendeleev's Periodic Table.
Some gaps were left as the elements to fill up these gaps had not been discovered at that time. 

Modern Periodic Table (1913):

Moseley modified Mendeleefs periodic law. He stated “Physical and chemical properties of elements are the periodic function of their atomic numbers.” It is known as modern periodic law and considered as the basis of Modern Periodic Table.

i) When the elements were arranged in increasing order of atomic numbers, it was observed that the properties of elements were repeated after certain regular intervals 01 2, 8, 8, 18, 18 and 32.

ii) These numbers are called magic numbers and cause of periodicity in properties due to repetition of similar electronic configuration.

Structural Features of Long Form of Periodic Table:

i) Long form of Periodic Table is called Bohr’s Periodic Table.
There arc 18 groups and seven periods in this Periodic Table.

ii) The horizontal rows are called periods.
   *First period (1H – 2He) contains 2 elements. It is the shortest period
   *Second period (3Li – 10Ne) and
   * Third period (11 Na – 18Ar) contain is elements each.These are short periods.
  *Fourth period (19K – 36Kr) and fifth period (37Rb – 54Xe) contain 18 elements each. These are long periods.
 *Sixth period (55Cs – 86 Rn) consists of 32 elements and is the longest period.
 *Seventh period starting with 87 Fr is incomplete and consists of 19 elements.

iii) The 18 vertical columns are known as groups.

 The periodic table can be classified based on groups:
Elements of group 1 are called alkali metals.
Elements of group 2 are called alkaline earth metals.
Elements of group 16 are called chalcogens [ore forming elements].
Elements of group 17 are called halogens. (sea salt forming).
Elements of group 18 are called noble gases.

Properties of the periodic table: 

Ionization energy:
The quantity of energy required to remove a specific electron from an atom, ion, or molecule.
i) Ionization energy decreases with increasing atomic size.
ii) with increasing distance between the electron to be removed and the nucleus.
Electron Gain Enthalpy (EGE or ΔHe g):

It is the amount of energy released when an electron is added in an isolated gaseous atom.

Various factors with which electron gain enthalpy varies are :

(i) Atomic size: varies directly
(ii) Nuclear charge: varies directly

Along a period, electron gain enthalpy becomes more and more negative while on moving down the group, it becomes less negative.

Electro-negativity (EN):
It is defined as the tendency of an atom to attract the shared electron pair towards itself in a covalent bond.

 Various factors with which electronegativity varies are :

(i) Atomic size: varies inversely
(ii) Charge on the ion: varies directly,

In periods as we move from left to right electronegativity increases,
while in the groups electronegativity decreases down the group.

Valency:
It is defined as the combining capacity of the element.

On moving along a period from left to right, valency increases from 1 to 4 and then decreases to zero (for noble gases).

 while on moving down a group the valency remains the same.

Atomic radius:
It is defined as the distance between the centre of the nucleus and the outermost shell of electrons.

i)it's difficult to measure from isolated an atom from other atoms.

ii) Within a period, there is a regular decrease in atomic radius with increasing atomic number.

iii) Within a group, there is a regular increase in atomic radius with increasing atomic number.

iv) Atomic Radius can be measured by covalent radius, ionic radius,van der waal's radius.

Ionic radii:
It is defined as "The distance between the nucleus of an ion and a point upto which the nucleus has influence on its electron cloud".
(i)Ionic radius increases going from top to bottom and decreases across the periodic table.

Hydrogen bonding:
It is defined as "the force of attraction existing between hydrogen atom covalently bonded to highly electronegative atom (N, O or F) and the electronegative atom belonging to another molecule of the same or different substance" .
Types of hydrogen bonds are:

(i) Intermolecular H-bonding :
 H-bonding involving two or more molecules.
(ii) Intramolecular H-bonding :
H-bonding within a molecule.

Anomalous properties of water:
1)Abnormal Boiling Point:

i) Due to hydrogen bonding water has an abnormal boiling point.
ii) water molecules are held by hydrogen bond which causes association of water molecules.
iii) More energy needed to break the bond, hence B.P of water is 100'c.

2)Density of ice less than the density of water:
i) The number of hydrogen bonds is larger in ice than the water.
ii)As ice is a solid and rigidly heldhin space.
iii) oxygen atoms are tetrahydrally sarrounded by 4 Hydrogen atoms. And 2 H-H atoms are bounded covalently.
iv) In ice these are arrenged cage like structure with vacant space.
v) hence ice has an expanded structure.

3)Water has a maximum density at 4°c:

As temperature rises to over 4° C, Water starts to flow and the molecules start to move away from each other due to which the Volume again increases and Density decreases.

Thus, Density is maximum at 4°C.

4)High Polar nature of water:
Water is highly polar due to the presence of highly electronegative oxygen atom present in the molecule. 

5)Due to hydrogen bonding, water has abnormally high specific heat, high latent heat of fusion and vapourisation and high tension.