Chemistry

Periodic Classification and Elements

1,176 Questions

Periodic classification organizes chemical elements based on atomic structure, periodic laws, and elemental properties. It covers historical classification systems, electron configurations, and periodic trends. Test takers preparing for chemistry sections will find these questions crucial for mastering fundamental element properties and atomic interactions.

Periodic table structureAtomic orbitalsElement identificationPeriodic laws

Periodic Classification and Elements Questions

Multiple choice

Consider that an electrovalent compound exists in the form XY. Which of the following can be the possible numbers of valence electrons in X and Y?

  1. X – 3, Y – 4

  2. X – 2, Y – 8

  3. X – 2, Y – 6

  4. X – 3, Y – 6
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The element X has 2 electrons in its valence shell. So, X is a metal and it will prefer to lose 2 electrons. The element Y has 6 electrons in its valence shell. So, Y is a non-metal and it will prefer to gain 2 electrons. Therefore, the compound between X and Y is ionic and will have the formula XY.                                                                                                            

Multiple choice

Which of the following statements regarding an element is false?

  1. Elements combine randomly to form a compound.

  2. Elements are represented by symbols.

  3. The atoms of an element are different from atoms of other elements.

  4. The number of atoms present in a molecule of an element is known as the atomicity of the element.

  5. A compound can be split into simpler substances or elements.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

No, elements combine in fixed proportion by mass to form a compound.

Multiple choice

Which of the following statements is true about the Mendeleev’s periodic table?

  1. In Mendeleev’s periodic table, atomic masses of the elements increase in a regular manner.

  2. It was possible to predict the number of elements that could be discovered between two elements.

  3. Existence of hydrogen as a diatomic molecule was explained by the Mendeleev’s periodic table.

  4. Mendeleev used a Sanskrit numeral to name the undiscovered elements.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

From above given statements, option (4) is correct, as Mendeleev used a Sanskrit numeral to name the undiscovered elements. 

Multiple choice

How does the non-metallic character of elements vary on moving down a group?

  1. Decreases

  2. Increases

  3. Remains same

  4. Varies according to a particular period
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The atoms showing tendency to gain one or more electrons is said to be non-metallic. On moving down a group, the atomic radii of atoms increase. This results in less effective attraction from nucleus side for the electrons in the outermost shell. So, down the group, the tendency to lose electrons increases, while the tendency to gain electrons is reduced. Hence, the non-metallic character decreases as we go down a group.

Multiple choice

An atom is said to be non-metal, if :

  1. it loses one or more electrons

  2. it gains one or more electrons

  3. it has more number of electrons than protons

  4. it has lesser number of electrons than protons
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An atom is said to be non-metallic if it gains one or more electrons when supplied with energy.

Multiple choice

The electron affinity, on moving from group 1 to group 7 :

  1. decreases then increases

  2. decreases

  3. increases

  4. does not change
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 Moving from group 1 to group 7, i.e., along a period from left to right, there occurs an increase in nuclear charge as well as decrease in atomic size. Both these factors make the electrons tightly bound towards the nucleus, thus making it difficult for them to be lost. This increases the electron affinity.