Classification ...

The successive ionisation energy values for an element 'X' are given below:

(i)     1^st ionisation energy = 410 kJ mol^-1
(ii)    2^nd ionisation energy = 820 kJ mol^-1
(iii)   3^rd ionisation energy = 1100 kJ mol^-1
(iv)   4^th ionisation energy = 1500 kJ mol^-1
(v)    5^th ionisation energy = 3200 kJ mol^-1

Find out the number of valence electrons for an atom of 'X'.

Correct option to complete the following statement  is :
"Mendeleeve's classification of element is based upon similarites in properties of different elements with increasing order of their atomic weights .
In cases where  dissimarites in properties of an element appeared he placed the elements with similar ......... together".

In the modern periodic table

The existence of which of the following became the reason for the failure of Mendeleev's periodic law?

Mendeleev 'Periodic Law' states that

Choose one of the following in the order of increasing radii:

Which of the following statements is correct?

Dmitri Mendeleev (1834-1907) and the German chemist, Lothar Meyer (1830-1895) proposed arranging elements in

The elements of the same group of the periodic table have the same

Mendeleev arranged the elements on the basis of their

The correct order of ionisation energies is  

In which of the following arrangements is the order NOT according to the property indicated against it?

Which of the following arrangements represents the correct order of electron gain enthalpies (with negative sign) of the given atomic species?

The numbers of periods and groups in the long form of periodic table respectively are

Which of the following options contains a pair of elements that do not belong to the same group?

In any period, the valency of an element with respect to oxygen

Man-made elements belong to _____ series.

Which of the following has the largest size?

Among 3^rd row elements, the atomic size is the maximum for 

Directions: The following question has four choices out of which ONLY ONE is correct.

Energy of 24.6 eV is required to remove the first electron from a helium atom. The total energy (in eV) required to remove both the electrons from He atom would be

Mendeleev arranged elements in a periodic table in order of their increasing atomic weights in such a way that the elements with similar properties occupies

It is now recognized that the ‘Modern Periodic Law’ is essentially the consequence of 

The first ionisation potential of Na is 5.1 eV. The value of electron gain enthalpy of Na⁺ will be

Mendeleev proposed that some of the elements were still undiscovered and, therefore, left several gaps in the table. He left the gap under aluminium and a gap under silicon, and called these elements Eka-Aluminium and Eka-Silicon. These were later discovered and named

Alkali metals belong to

Which of the following statements is true?

Complete the statement with suitable  word /(s)
Modern Periodic Law is stated as:
"Physical and chemical properties of different elements are periodic functions  of their ......... ?

Modern periodic law states that the periodic properties of elements are the periodic function of

The first, second and third ionisation energies of an atom are 737, 1451 and 7733 kJ mol^–1, respectively. The element can be 

According to the recommendation of International Union of Pure and Applied Chemistry (IUPAC), the groups in the modern periodic table are numbered from