Modern Periodic Table: Introduction, Features, Trends

The periodic table lists all the elements known to man, arranged in order of increasing atomic number and recurrent chemical properties. According to the modern periodic table, the physical and chemical properties of the elements are periodic functions of their atomic numbers. 

Have you ever wondered that the jewellery we wear, different types of parts used in motorcycles, the air we breathe, and the semiconductors used in computers are all made up of different elements? There are around \(118\) elements in the modern periodic table based on the study of nature around us. This article will learn about the Modern Periodic law, Modern periodic table chart, its features, and trends.

What is Modern Periodic Table?

In \(1913\), Henry Moseley, from his studies on X-ray, found that the atomic number is the fundamental property of an element but not atomic mass. The atomic number is equal to the number of electrons or protons in a neutral atom. Later, Neils Bohr gave the extended form of the periodic table, known as the long form of the periodic table.

Modern Periodic Law

Henry Moseley propounded the modern periodic law. This law states that the properties of elements are the periodic functions of their atomic number, i.e., if the elements are arranged in tabular form in the increasing order of their atomic numbers, then the properties of the elements are repeated after definite regular intervals or periods.

Definition

A systematic arrangement of elements into groups and periods based on similarities in chemical properties and the order of their increasing atomic number is called a modern periodic table. This arrangement is known as the long form of the periodic table.

Features of Modern Periodic Table

Periods:

There are seven horizontal rows in the periodic table, and each row is called a period. The elements in a period have continuous atomic numbers. The number of elements in each period is given below:

Groups:

The vertical columns in a periodic table are called groups. There are \(18\) vertical columns in the periodic table and are arranged from left to right. The elements present in a group have the same valency and identical chemical properties. The physical properties of the elements in the group very gradually.

Types of elements in Modern Periodic Table

1. Main group elements: The elements present in groups \(1\) and \(2\) on the left-hand side and Groups \(13\) to \(17\) on the right-hand side of the periodic table are called main group or representative elements.

2. Noble gases: These elements are present in group \(18\) of the periodic table, and they have completely filled outermost shells; therefore, making them non-reactive.

3. Transition elements: These elements are present in the middle block of the periodic table (Group \(3\) to \(12\)) and contain incomplete two outermost shells; due to this they change from most electropositive elements to most electronegative elements. Hence, they are called transition elements.

4. Inner transition elements: These are placed in two separate rows at the bottom of the periodic table to avoid the expansion of the periodic table. There are two series of \(14\) elements each. The first series, called lanthanoids consists of elements \(58\) to \(71\) (Ce to Lu). The second series of \(14\) rare-earth elements are called actinides. It consists of elements \(90\) to \(103\) (Th to Lr).

5. Metals: Metals are placed at the left-hand portion of the periodic table. Group one metals are called alkali metals, and group two metals are called alkaline earth metals.

6. Non-metals: Non-metals occupy the right-hand portion of the periodic table.

7. Metalloids: Metalloids are the elements that show the properties of both metals and non-metals. They are present along the diagonal line starting from group \(13\) (Boron) and going down to group \(16\) (Polonium).

Trends in Modern Periodic Table

a. Valency

It is defined as the combining capacity of an atom of an element to acquire noble gas configuration.
Down a group: All the elements present in a group have the same valence shell electronic configuration of their atoms. Therefore, they have the same valency.
Across a period, the elements have different valencies.

b. Ionisation energy

Ionization energy is required to remove an electron from a gaseous atom or ion to form a positive ion.
Across a period, the ionization energy increases, and the ionization energy decreases down a group.

c. Atomic size (atomic radius)

Atomic radius is the distance between the centre of the nucleus of an atom and its outermost shell. Atomic size increases down a group and decreases along a period.

d. Electron affinity

The amount of energy released while converting a neutral gaseous isolated atom into a negatively charged gaseous ion (anion) by adding electrons is called Electron Affinity.

Moving from the top to the bottom in a group, electron affinity decreases, and across a period, electron affinity increases.

e. Metallic and non-metallic characters

Metallic character: Elements that tend to lose valence electrons and form positive ions are considered metals.
On moving down, the group metallic character increases, and the metallic nature decreases across a period.

Non-metallic character: Elements that tend to gain electrons to attain octet in their outermost orbit are non-metals.
Down the group, the non-metallic character decreases, and the non-metallic character increases across a period.

f. Electronegativity

The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called electronegativity.
As we godown the group, the electronegativity decreases, and along a period, it increases.

Advantage/Merits of Modern Periodic Table

1. Position of isotopes: All isotopes of an element have the same atomic number. Therefore, they occupy the same position in the modern periodic table.
2. Anomalous pairs: When the atomic number is used as the basis for classification, the anomaly of the pairs disappears. For example, cobalt (atomic number \(27\)) would naturally come before nickel (atomic number \(28\)), even though its atomic mass is a little more than a nickel.
3. Electronic configuration: In the modern periodic table, the elements with a certain pattern of electronic configuration are placed in the same group. Hence, this classification relates the properties of elements to their electronic configurations.
4. Separation of metals and non-metals: The modern periodic table establishes the position of metals, non-metals, and metalloids.
5. Position of transition metals: It makes the position of the transition elements quite clear.
6. Properties of elements: It reflects the differences, trends, and variations in the properties of the elements in the periodic table.
7. This table is a simple, systematic, and easy way of remembering the properties of different metals.

Defects in the Modern Periodic Table

1. The position of hydrogen is still debatable because its electronic configuration is similar to that of alkali metals. Thus, it can be placed in Group I with the alkali metals. The electronic configuration of hydrogen is also similar to that of halogens; hence it can be placed with halogens too.
2. The position of lanthanides and actinides is not defined in the periodic table.
3. It does not reflect the exact distribution of electrons of some of the transition and inner transition elements.

FAQs

Q.1. What is the name of a modern periodic table?
Ans: Modern periodic table is also known as Bohr’s periodic table?

Q.2. Who is the father of the modern periodic table?
Ans: Henry Moseley is the father of the modern periodic table.

Q.3. Who is the father of science?
Ans: Galileo Galilei is the father of science.

Q.4. Give two drawbacks of the modern periodic table.
Ans: The drawbacks of the modern periodic table are as follows:
a. Position of hydrogen is not fixed till now.
b. Position of lanthanides and actinides is not defined in the periodic table.

Q.5. Who proposed the modern periodic table?
Ans: Henry Moseley proposed the modern periodic table in the year \(1913.\)

Q.6. Is the modern periodic table based on atomic masses?
Ans: No, the modern periodic table is based on the atomic number.

Q.7. What is the modern periodic table law?
Ans: Modern periodic law states that if the elements are arranged in tabular form in the increasing order of their atomic numbers, then the properties of the elements are repeated after definite regular intervals or periods.

Q.8. What are the advantages of the modern periodic table?
Ans: The advantage of the modern periodic table is as follows:
a. All isotopes of an element have the same atomic number and occupy the same position in the modern periodic table.
b. When the atomic number is used as the basis for classification, the anomaly of the pairs disappears.
c. In this classification, the elements having a certain pattern of electronic configuration is placed in the same group of the periodic table
d. The position of metals, non-metals, and metalloids is clearly established in the modern periodic table.
e. It makes the position of the transition elements quite clear.

Q.9. Who is the first father of chemistry?
Ans: Jabir ibn Hayyan is the first father of chemistry.

Q.10. Who gave the modern periodic table?
Ans: Henry Moseley gave the modern periodic table.

Study Materials On Embibe

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From this article, we can conclude that the modern periodic table is important because we can study the properties of each element based on their positions in the periodic table. It also helps us to understand the uses and properties of elements in daily life.