Question

Which of the following statements is correct? (a) Elements of \(3 d\) and \(4 d\)-series are kept separately in periodic table. (b) Elements of \(4 f\) and 5 f-series are kept separately in periodic table. (c) Elements of \(5 p\) and 6p-series are kept separately in periodic table. (d) All statements are correct.

Short answer

The correct statement is (b) Elements of 4f and 5f-series are kept separately in periodic table.

Step-by-step solution

Analyze Statement (a)

The elements of the 3d and 4d-series are transition elements and are found in the central block of the periodic table, known as the d-block. However, they are not kept separately; they are in sequential periods. 3d elements are placed in the fourth period while 4d elements are in the fifth period following the 3d-series.

Analyze Statement (b)

The elements of the 4f and 5f-series do have their own separate blocks in the periodic table. These series are known as the lanthanides and actinides, respectively. The elements of 4f-series are placed at the bottom of the periodic table separated from the main body, similarly, the 5f-series elements are placed in a separate row right below the 4f-series.

Analyze Statement (c)

Elements of the 5p and 6p-series are p-block elements, and they are not kept separately in the periodic table. They are placed in the 5th and 6th periods of the periodic table, following their respective groups.

Identify the Correct Statement

After analysing all statements, it is evident that statement (b) is correct because the 4f and 5f-series elements are kept separately in the periodic table, in the lanthanide and actinide series, respectively.

Key concepts

Transition Elements

Transition elements, also known as transition metals, are a group of elements found in the central part of the periodic table. They are characterized by their ability to form stable ions that have incompletely filled d orbitals.

These elements are placed in the d-block of the periodic table and include metals from Groups 3 to 12. The transition elements are unique in that they exhibit variable oxidation states, form coloured compounds due to d-d electron transitions, and generally act as good catalysts.

For instance, iron, a well-known transition metal, can exist in oxidation states ranging from 2+ to 6+. This variability is crucial in biochemical processes and industrial applications. Additionally, the transition elements are known for their metallic properties, such as high conductivity and malleability.

Lanthanides and Actinides

The lanthanides and actinides are two series of elements that are placed below the main body of the periodic table to maintain its structure and readability.

The lanthanides, also known as the rare earth elements, consist of elements with atomic numbers 57 to 71 (from lanthanum to lutetium). These elements are f-block elements and are well-known for their magnetic, catalytic, and luminescent properties. For example, neodymium is used in powerful magnets, while europium is used in fluorescent lamps.

On the other hand, the actinides, comprising elements with atomic numbers 89 to 103 (from actinium to lawrencium), are all radioactive. The most familiar actinides are uranium and plutonium, which are used as fuel in nuclear reactors and atomic bombs, respectively. Both lanthanides and actinides have electrons filling up their 4f and 5f orbitals, and these series are separated from the rest of the periodic table due to their distinct properties.

D-block Elements

D-block elements are a subset of transition metals occupying groups 3 to 12 of the periodic table, with their valence electrons primarily in the d subshell.

The d-block is often referred to as the 'transition metals' section because these elements exhibit behavior typical of both metals and nonmetals. D-block elements are known for their complex formation, high melting and boiling points, and conductive properties. They are also very versatile in terms of the compounds they form.

Interestingly, the d-block includes several important metals such as copper, silver, and gold, which have been historically significant for currency and jewelry. These elements are also essential for modern industry, used in the manufacture of electronics, catalysts, and various alloys. Within the d-block, there is a wide range of variation in electron configurations, allowing a rich chemistry that is vital to many biological and technological processes.