Question

5f series elements are known as (a) lanthanides (b) representative elements (c) transition elements (d) actinides

Short answer

Answer: (d) Actinides

Step-by-step solution

Consider the options

The 5f series elements can belong to one of the following groups: (a) Lanthanides (b) Representative elements (c) Transition elements (d) Actinides

Recall the location of each group in the periodic table

Before we can identify which option is correct, it is helpful to review where each group of elements is located within the periodic table: (a) Lanthanides: 4f series elements in Period 6 (b) Representative elements: elements in Groups 1, 2, and 13-18 (c) Transition elements: elements in Groups 3-12 in the d-block (d) Actinides: 5f series elements in Period 7

Identify the correct group

Based on the location of each group of elements in the periodic table, we can see that the 5f series elements are part of the actinides group. Therefore, the correct answer is: (d) Actinides

Key concepts

5f series elements

The 5f series elements are often referred to as the actinides. These are elements found in the 7th period of the periodic table, specifically placed in the f-block. The 5f orbitals are being progressively filled from actinium (Ac, atomic number 89) to lawrencium (Lr, atomic number 103). Actinides are known for their radioactive properties, and they include some of the heaviest elements known. They are mostly synthetic and include well-known elements like uranium and plutonium. Understanding these elements is crucial for nuclear chemistry due to their ability to undergo fission reactions.

Periodic Table groups

The periodic table is organized into several groups and blocks that help us classify elements based on their properties. Major groups include:

• Group 1 and 2: These are the alkali and alkaline earth metals respectively, highly reactive metals.
• Groups 3 to 12: Known as the transition metals, these elements are characterized by their ability to form multiple oxidation states.
• Groups 13 to 18: These are the p-block elements, encompassing nonmetals, metalloids, and post-transition metals.
• f-block elements: These include the lanthanides and actinides, having their valence electrons in the f-orbitals.

Recognizing these groups helps in understanding the chemical behavior and reactivity of the elements.

Lanthanides vs Actinides

Lanthanides and actinides are both series of elements found in the f-block of the periodic table. The lanthanides are the 4f series which begin with lanthanum and end with lutetium. They are known as rare earth elements and are mostly used in various industrial applications such as catalysts and phosphors in electronic devices. In contrast, actinides are the 5f series elements, starting with actinium and ending with lawrencium. They are mostly radioactive, and many are synthetically produced. Their applications are more related to their nuclear properties, important for energy and weaponry. Both series exhibit similar chemical properties due to the filling of f-orbitals, but their practical uses and occurrences differ greatly.

Transition and Representative Elements

Transition and representative elements form two distinct sections of the periodic table. Transition elements, located in groups 3 through 12, are defined by the filling of d-orbitals. They are known for high melting points, conductivity, and their ability to form colored compounds due to d-d electron transitions. Representative elements, on the other hand, are found in Groups 1, 2, and 13 through 18, showing a wide range of properties. These include metals, nonmetals, and metalloids and are involved in many of the essential compounds of life. Both groups are vital to understanding elemental chemistry, with transition elements often used in industry and representative elements being crucial for biological systems.