Classification of Elements and Periodicity in Properties
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Johann Wolfgang Dobereiner, a German chemist, first made an effort to organize elements with similar properties into three-element groups. The triads was the name given to those groups. Dobereiner suggested that the triads, in the middle, the atomic mass would be more or less equal to the mean of the atomic masses of the other two elements.
Limitation of Dobereiner’s Triads are:-
- At that time, all familiar elements cannot be classified into triads.
- Li, Na, K +Ca, Sr, Ba + Cl, Br, I + S, Se, Te are the sole triads mentioned by the Dobereiner.
In 1866, John Newlands, an English Scientist, arranged 56 known elements in increasing order of atomic mass. A tendency was noticed by him wherein every eighth element manifested properties indistinguishable to the earliest one.
Newland’ Law of Octaves
It states that when the elements are arranged in increasing order of atomic mass, the two elements in the periodicity in properties with an interval of seven elements in between them would be identical. This method of classification laid the foundation of the modern periodic table that we study now.
Limitation of Newland’s Octaves are:-
- Only up to calcium, via Newland’s Octaves, the elements are categorized.
- Since the noble gases are a constraint of this technique and, without disturbing the arrangement entirely, it cannot be incorporated.
In 1869, Dmitri Ivanovich Mendeleev, a Russian chemist, discovered this periodic table. He believed that both the physical and chemical properties of elements were linked to the atomic mass of the elements periodically.
Advantages of Mendeleev’s Periodic table are:-
- There is no disturbance in the periodic table if there is any addition of these freshly found elements.
- The incorrect atomic weights used can be correct using Mendeleev’s Periodic table.
- Mendeleev’s table provides a difference from the atomic weight.
Limitation of Mendeleev’s Periodic table are:-
- Hydrogen also exhibited halogen like qualities but, hydrogen’s position was in the group of alkali metals.
- In this type of categorization of elements, isotopes were positioned differently. This classification was achieved by taking into consideration the atomic weight of the elements. Therefore varying positions in Mendeleev’s table would be occupied by protium, deuterium, and tritium.
- Atomic masses do not increase commonly from one element to the succeeding element, as shown by the abnormal positioning of the few elements.
To honor Dmitri Ivanovich Mendeleev, the modern periodic law we study is also known as Mendeleev’s Law. The Law states that elements’ chemical properties are regular functions of their atomic weights.
- What is periodicity in the properties of the element?
Answer: After a specific interval, when there is a repetition of properties, it is called periodicity of properties. The elements repeat their properties after a definite interval if they are arranged in increasing order of their atomic number in the periodic table. Therefore this repetition of properties is called the periodicity of properties.
- What are the 3 main classifications of elements on the periodic table?
Answer: Depending on their properties, the elements in different groups are lumped together in one of three classes. The 3 classes are:
- Metals: They are shiny and have classic metal characteristics. Easily electrons are lost, and they are a good conductor of heat and electricity.
- Nonmetals: They are poor conductors of heat, have low boiling points, and electrons are not lost easily. There are mainly two types of P-Block nonmetals: solid and liquid. Example of solid: carbon, sulfur, phosphorus, and liquid: bromine.
- Metalloids: Both metals and nonmetals are the properties of Metalloids. But there is no universal definition of the term “Metalloids.” As Metalloids, the elements that are conceded are in the P-Block, such as boron, silicon, germanium, arsenic, tellurium, and antinomy. One of the best metalloids is silicon. It is used in many electronic devices.
- What are the properties of an element?
Answer: The properties include:
- Melting point
- Boiling point
- Thermal and electrical conductivity
- How many types of elements are there?
Answer: There are a total of 118 elements on a periodic table.
- What are the 7 groups of the periodic table?
Answer: The following are the 7 groups of the periodic table:-
- Alkali metals: It is part of group 1, it is in the first column of the table, and they are shiny and soft enough to cut using a knife
- Alkaline-earth metals: It forms the 2nd group.
- Lanthanides: It forms the 3rd group. This group is way too long.
- Actinides: It is the bottom row of the table and consists of 89 elements.
- Transition metals: The remainder of Groups 3 through 12 represent the rest of the transition metals.
- Metalloids: It has properties of both metal and nonmetals elements.
- Halogens: They are quite chemically reactive.
The classification of elements and periodicity in properties is the basics of chemistry and the most crucial topic. You should try to understand the core concept behind it; we have a solution for you. You can grasp the concept with an explanatory video on the MSVgo app and on their official site. The MSVgo philosophy is to enable a core understanding of any concept. The video library of the MSVgo app explains concepts with examples or explanatory visualizations or animations