Periodic Table of Elements 2021 Free PDF Download : periodic table in hindi, Modern periodic table in hindi, Prout’s hypothesis in hindi, Dobereiner’s law of triads, Limitations Dobereiner’s law, Newland’s law of octaves in Hindi, Limitation of Newland’s law, Modern periodic law in hindi, Mendeleev’s Periodic Table in Hindi, Lothar Meyer’s Atomic Volume Curve in Hindi.
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- 1 List of the Elements
- 2 Prout’s hypothesis
- 3 Dobereiner’s law of triads
- 4 Limitations Dobereiner’s law of triplet
- 5 Newland’s law of octaves
- 6 Limitation of Newland’s law of octaves
- 7 Lothar Meyer’s Atomic Volume Curve
- 8 Mendeleev’s Periodic Table
- 9 Mendeleev’s Periodic Table Profile
- 10 Mendeleev’s Periodic Table’s Features
- 11 Limitation of Mendeleev’s Periodic Table
- 12 Modern periodic table
- 13 Features of Modern periodic table
- 14 Group
- 15 first period
- 16 second and third periods
- 17 fourth and fifth period
- 18 sixth period
- 19 seventh period
List of the Elements
|Atomic Number||Element Name||Symbol||Atomic Weight||Electronegativity|
Prout, based on Dalton’s theory of atomism and the atomic mass of some elements, hypothesized that the atomic mass of elements is a simple coefficient of the atomic mass of hydrogen.
Limitation of Prout’s hypothesis
तत्वों के परमाणु भार पूर्ण संख्या में न होकर भिन्न में भी पाये जाते।
Dobereiner’s law of triads
Dobereiner made triplets of three elements each.
In a triplet, when elements with similar properties are placed in increasing order of their atomic mass.
The atomic mass of the middle element in their triad is (approximately) equal to the average value of the atomic mass of the remaining two elements.
|Li 7||Be 8|
|Na 23||Mg 24|
|K 39||Ca 40|
Limitations Dobereiner’s law of triplet
Dobereiner could arrange only a few elements in the form of triples.
All the elements present in the triad have almost the same atomic weight. like
Newland’s law of octaves
Newland also classified the elements in increasing order of their atomic mass.
According to the rule of octet, just as the 8th note in music is equal to the first note, similarly if the elements are arranged in the increasing order of their atomic weights, then the properties of each of the first elements are similar to the properties of the eighth element. shows. like –
The eighth element of lithium in this table is sodium, whose properties are similar to those of lithium. Similarly, the properties of magnesium, the eighth element of beryllium, are similar to those of beryllium.
The properties of aluminum, the eighth element of boron, are similar to those of boron.
Limitation of Newland’s law of octaves
This classification remained limited to only 14 elements, but after the discovery of noble gases, the eighth element, noble gas, comes. which is not identical with the first element.
Lothar Meyer’s Atomic Volume Curve
Lothar Meyer related the physical properties of elements to their atomic volumes.
If the graph is drawn by relating the atomic volume with the atomic masses, then it is called Lothar Meyer’s volume curve.
Alkaline earth metals which are relatively less rich such as Be, Mg, Ca, Sr, Ba etc. lie in the descending part of the curve.
The halogens and noble gases (besides helium) occupy the ascending part of the curve.
Alkali metals have maximum volume, so they were found at the top position in the curve. It is a strong electronegative element.
Mendeleev’s Periodic Table
Mandeleev’s Periodic Law : According to it, “The physical and chemical properties of elements are periodic functions of their atomic masses.”
What is a periodic function?
The meaning of the periodic function is that if the elements are placed on the basis of increasing atomic mass, then their properties repeat after a certain interval.
Mendeleev’s Periodic Table Profile
In this periodic table, the elements are arranged in increasing order of atomic weight.
In the periodic table, the horizontal rows are called periods, and the vertical rows are called squares.
Mendeleev’s periodic table has 7 periods and 8 groups. The zero class of inert gases were added later. Because inert gases were not discovered at that time Mendeleev made the periodic table.
Each class is divided into A and B. (Except eighth and zero squares)
2, 8, 18 and 32 are called magic numbers.
Mendeleev’s Periodic Table’s Features
For the first time the elements known up to that time were classified.
It also encouraged the discovery of new elements. Mendeleev had even predicted the properties of elements that were unknown at that time. This helped a lot in finding the elements. Thus Mendeleev predicted three elements.
Eka-boron was similar to the later discovered scandium (Sc).
Eka-aluminium, which was similar to the later discovered gallium (Ga).
Eka-silicon was similar to the later discovered germanium (Ge).
Limitation of Mendeleev’s Periodic Table
Indeterminate position of hydrogen The properties of hydrogen show similarity with both alkali metals and halogens. Didn’t get it for sure.
Explanation of Isotopes – Elements whose atomic mass and different atomic numbers are the same are called isotopes.
Since the Mendeleev periodic table is based on atomic mass, different isotopes should be given different positions.
An equal place for dissimilar properties – Elements with dissimilar properties such as alkali metals with coin metals Cu, Ag, and Au and alkaline earth metals with Z
Modern periodic table
According to the Modern Periodic Law, “The physical and chemical properties of elements are periodic functions of their atomic numbers.”
Henri Moseley proved that the square root of the frequency (v) of the rays received by a fast-moving electron on the metal is proportional to the nuclear charge of the metal atom, which can be explained by the following relation
Z = nuclear charge on the atom
a and b = constants
The nuclear charge on an atom is equal to the atomic number.
Features of Modern periodic table
On the basis of the modern periodic law, Wrang and Warner prepared and the periodic table was given long-form by Bohr.
In the periodic table, the horizontal lines are called periods, whose number is 7 and the vertical lines are called groups, whose number is 18.
- There are two elements in the first period. This is called very short period.
- There are 8-8 elements in the second and third. This is called the short period.
- There are 18-18 elements in the fourth and fifth. This is called long period.
- There are 32 elements in the sixth period, this is an incomplete period.
- There are 19 elements in the seventh period, this is an incomplete period.
- Lanthanide – The element from atomic number 58 to 71 is counted in the sixth period.
- Actinide – The element from atomic number 90 to 103 is counted in the seventh period.
- Although both these periods are placed outside the periodic table.
- Elements of the first group are called alkali metals. Like H, Li, Na, K, Rb, Cs Fr
- Elements of the second group are called alkaline earth metals. such as Be, Mg, Ca, Sr, Ba, Ra
- The elements in the third group are called the boron family. Like B, Al, Ga, In, Tl
- Elements of the 16th group are called the oxygen family, they are also called chalcogens. Like O, S, Se, Te, Po
- Elements of the 17th group are called halogens. Like F, Cl, Br, I, At
- 18 Those group elements are called inert elements, inert gases, noble gases. He , Ne , Ar, Kr, Xe, Rn
First period There are two elements H and He in the first period, this is called very short period.
second and third periods
There are 8-8 elements in the second and third, they are called short periods.
The elements of the second period are Li, Be, B, C, N, O, F and Ne.
The elements of the third period are Na, Mg, Al, Si, P, S Cl and Ar.
fourth and fifth period
Elements 18-18 in the fourth and fifth are called long periods.
Elements of the fourth period are potassium (K), calcium (Ca), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel. (Ni), copper (Cu), zinc (Zn), gallium (Ge)
There is germanium (Ge), arsenic (As), selenium (Se), bromine (Br), and kryptone (Kr).
Elements of the fifth period are rubidium (Rb), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), tellurium (Te), iodine (I) and xenon (Xe).
The sixth period is called the very long period. It has 32 elements. Which are Cesium (Cs), Barium (Ba), Lutetium (Lu), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum (Pt), gold (Au), mercury (Hg), thallium (Tl), lead (Pb), bismuth (Bi), polonium (Po), astatine (At), and radon (Rn). pending
Lanthanides are elements that are lanthanum (La), cerium (Ce), plasmodium (Pr), neodymium (Nd).
Promethium (Pm), Semerium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium,
There are holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb).
The seventh period is called the incomplete period, it has 19 or 32 elements. which is as follows-
So far a total of 109 elements have been discovered, but up to 105 elements have been studied in detail.
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