F block elements are divided into two series, namely lanthanoids and actinoids. This block of elements is often referred to as inner transition metals because they provide a transition in the 6th and 7th row of the periodic table, which separates the s block and the d block elements.

Table of Contents

Classification of F-Block Elements

Inner Transition Elements (F-Block)

Properties of F-block Elements

Difference between Lanthanides and Actinides

Frequently Asked Questions

F Block Elements are a group of elements in the periodic table that have the highest electron affinity. They are also known as inner transition metals.

Elements whose f orbital is filled with electrons are known as f block elements. These elements have electrons in the f orbital ranging from 1 to 14, in the d orbital of the penultimate energy level ranging from 0 to 1, and in the outermost orbital.

There are two series in the f block corresponding to the filling up of 4f and 5f orbitals. The elements are 4f series of Ce to Lu and 5f series of Th to Lw. There are 14 elements filling up the f orbital in each series.

The Position of F Block Elements in the Periodic Table: F Block elements are placed separately at the bottom of the periodic table, as a subset of the 6th and 7th periods.

F Block Elements: An Overview

Lanthanides

Actinides

Classification of F Block Elements

The elements belonging to the f-block are further divided into:

1. The first series of elements, known as lanthanides, span from element 57 to element 71. Except for promethium, which is radioactive, the other lanthanides are non-radioactive.

2. The second series of elements are referred to as actinides and include elements ranging from atomic number 89 to 103. These elements are typically radioactive in nature.

The list of all the f-block elements is provided below. The row beginning with Lanthanum contains all the lanthanides, whereas the row beginning with Actinium contains all the actinides.

F Block Elements as Inner Transition Elements

Since the f orbital lies much further inside than the d orbital, in relation to the transition metals, the f block elements are referred to as inner transition elements.

Properties of F-Block Elements

Add electrons to the ‘f’ sub-orbitals of the (n-2) level

The (n-1)d and ns block elements are placed between each other in the periodic table.

Properties are analogous to d-block elements.

Properties of the Lanthanides

Lanthanides are soft metals with a silvery-white color.

Their color fades and their luminosity decreases quickly when exposed to air.

Except for Samarium, which has a melting point of 1623K, the other elements have melting points ranging from 1000K to 1200K.

Lanthanides are excellent conductors of both heat and electricity.

Except for Promethium, they are non-radioactive in nature.

The lanthanoid contraction is observed when the atomic and ionic radii decrease from lanthanum to lutetium.

Properties of Actinides

The Actinide elements appear to be silvery.

These elements have a radioactive nature.

These metals are highly reactive and become even more reactive when they are in a finely divided form.

The actinoid contraction is observed due to a decrease in atomic and ionic radii from Actinium to Lawrencium.

Elements belonging to the first half of the series generally exhibit an oxidation state of +3, however, they are known to exhibit higher oxidation states quite frequently.

Difference between Lanthanides and Actinides

Lanthanides and actinides are two series of elements in the periodic table. Lanthanides are elements 57 through 71 on the periodic table, while actinides are elements 89 through 103. The main difference between the two is that lanthanides are all metals, while actinides contain both metals and metalloids. Additionally, lanthanides have a partially filled 4f orbital, while actinides have a partially filled 5f orbital.

Lanthanoids are involved in the filling of 4f-orbitals, while actinoids are involved in the filling of 5f-orbitals. The binding energy of 4f electrons is comparatively lower than that of 5f-electrons. Additionally, the shielding effect of 5f-electrons is less effective than that of 4f-electrons.

The paramagnetic properties of lanthanoids can be easily explained, however explaining this in the case of actinoids is more challenging.

Except for promethium, all lanthanides are non-radioactive, while all actinide series elements are radioactive.

The compounds formed by lanthanides are less basic, whereas the compounds of actinides are highly basic. Lanthanides generally do not form oxo-cations, whereas several oxo-cations of actinide series exist.

Similarities between Lanthanides and Actinides

The elements of the Lanthanide and Actinide series are characterized by filling of the (n-2) f subshell. Due to the similar outermost electronic configuration, these elements possess many similar properties, including the following:

1. They both have a prominent oxidation state of +3.

2. They are involved in the filling of (n-2) f orbitals.

3. They are highly electropositive and very reactive in nature.

4. With an increase in atomic number, there is a decrease in atomic and ionic size.

5. Both show magnetic properties.

Frequently Asked Questions

1. What metals are in the F block?

Answer: The F block elements are known as the inner transition metals, and include lanthanides and actinides.

2. Why are F block elements placed separately?

No, not all F block elements are radioactive.

What element is the last of the F block?

5. What are the characteristics of F Block Elements?

What is the electronic configuration of F-block elements?

7. Lanthanides and actinides are collectively known as the “rare earth elements”.

8. Why are F block elements called inner transition elements?

D and F Block Elements - Oxidation States

15 Crucial Questions on D-Block and F-Block Elements

Alloy Formation of d- and f-Block Elements

Colors of Ions in d- and f-Block Elements

Frequently Asked Questions (FAQs)

The two metals in F block elements that are colourless are Scandium and Yttrium.

No, not all F block elements are radioactive.

No, F block elements are not radioactive except for the element Promethium (Pm).

The last element of F block elements is Radon (Rn).

Lawrencium (Lr) is the last element of the F block series.

The general electronic configuration of F-block elements is [Xe] 4f¹⁴ 5d¹ 6s².

The general electronic configuration of F-Block elements is (n-2)f^0-1(n-1)d^0-1ns².### Why are F block elements called inner transition elements?

F block elements are called inner transition elements because they are located between the s and d blocks on the periodic table.

F-block elements are called inner transition elements because their last electron enters the shell that is inner to the shell in which the last electron of d-block elements enters. Therefore, D-block elements are referred to as transition elements, and F-block elements are known as inner transition elements.