In 1817 scientist Dobereiner arrange the elements with similar properties into group
when three elements in a traid were written in order of increasing atomic masses atomic mass of the middle element was the average of atomic masses of other two elements
Que 3
What is Newland law of octaves
Ans
In 1866 John newland arrange the known elements in the order of increasing atomic
masses
He found that every eighth element has the similar properties to that of the first
He compare this to the octaves found in music therefore he called it the law of octaves
Que 4
How many elements were known at the time of mendeleev classification of periodic table
Ans
64
Que 5
What is the periodic law for mendeleev periodic table
Ans
"The properties of elements are the periodic function of their atomic masses "is the periodic law for the mendeleev periodic table
Que 6
What is the name given to the vertical columns and horizontal rows in the periodic table
Ans
The vertical columns are called groups
Horizontal rows are called periods
Que 7
What are the limitations of mendeleev periodic table classification
Ans
The position of the hydrogen cannot be fixed as hydrogen has both the properties of alkali and the halogens
There is no place for the isotopes of the element
Que 8
What is the basis of Mendeleev periodic table
Ans
Mendeleev arrange the elements in order of their increasing atomic masses
Que 9
Who discovered atomic number
Ans
In 1913 Henry Moseley
Que 10
What is the basis of modern periodic table
Ans
The modern periodic table is arranged on the basis of the atomic number
Que 11
What is modern periodic law
Ans
Properties of elements are a periodic function of their atomic number
Que 12
How many vertical columns and horizontal rows are found in modern periodic table
Ans
There are 18 vertical columns known as groups
There are 7 horizontal rows known as periods
