What is Debenerener`s law of triads? Explain with an example of the Doberein triad. The first Doberein triad was discovered in 1817. It consists of alkaline earth metals, i.e. calcium, strontium and barium. Later, three more triads were discovered. Let`s look at these triads in detail. There are five of Dobereiner`s triads, which are as follows: Although Dobereiner`s triads cannot group all elements according to their properties, he said the basis for the formation of the modern periodic table. For example: calcium, strontium and barium have atomic weights of 40, 88 and 137 and form a triad and have similar chemical properties. The atomic mass of strontium is approximately equal to the average atomic masses of calcium and barium. According to Dobereiner`s law of triads, when elements are arranged in ascending order of their atomic masses, a group of three elements with similar chemical properties is obtained. This group is called the Triad.
The atomic mass of the middle element is equal to the arithmetic mean of the atomic masses of the other two elements. For example, the elements: calcium (Ca), strontium (Sr) and barium (Ba) with atomic masses of 40, 88 and 137 each form a triad because they have similar chemical properties, and the atomic mass of strontium is roughly equal to the average atomic masses of calcium and barium. Arithmetic mean of atomic weights of calcium and barium = 40+1372=88.5 Question 5: Check whether carbon, nitrogen and oxygen with atomic weights of 12, 14 and 16 Dobereiners form triads. Question 4: Which halogens belonged to Dobereiner`s triads? The law of triads can be verified for this triad as follows: The boundaries of the Doberein triads were as follows: According to Dobereiner`s law of the triad, when elements are arranged in ascending order of their atomic weights, a group of elements with similar chemical properties is obtained. These are called triads. The atomic mass of the middle element is equal to the arithmetic mean of the atomic masses of the other two elements. 87.5 is very close to the atomic mass of strontium. This verifies the law of the Triads.
Let`s also check the law of triads for this triad. A German chemist Johann Wolfgang Dobereiner identified that elements with similar properties could be grouped into groups of three called triads. The elements of a particular triad had similar chemical and physical properties. The triad of alkali metals is made of lithium. Sodium and potassium. The atomic weights of these elements are 7, 23 and 39 respectively. The arithmetic mean of the masses of lithium and potassium is equal to 23, which corresponds to the atomic mass of sodium. Thus, the law of the Triads is verified.
Since ancient times, there have been various attempts to divide elements into groups according to their properties. When the new elements were discovered, a number of theories emerged to classify the elements. Different scientists have used different approaches and facts to justify their classification. These theories became increasingly refined and eventually led to the development of the modern periodic table. Let`s take a look at one of those old theories, namely Dobereiner`s triads. Question 3: Specify any two constraints of Dobereiner`s triads. For example, lithium in the alkali metal group (Doberein`s triad) is 1. Element, sodium is the intermediate element, while potassium is the 3rd element of the triad.
Although the Dobereiner triads tried to classify elements into groups of three based on their properties, they still had various limitations, which will be discussed below: The alkaline earth metals that are part of the Doberein triads are calcium, strontium and barium. Question 2: What do you mean by triad in terms of Doberein triads? With respect to Dobereiner`s triad, the triad refers to a group of 3 elements. According to Dobereiner, the elements could be converted into groups of three with similar physical and chemical properties. To form a Doberone triad, the arithmetic mean of the atomic mass of the first and third elements must be approximately equal to the atomic mass of the second element. Here, the arithmetic mean of the atomic mass of carbon and oxygen is 14, which corresponds to the atomic mass of nitrogen. Therefore, they form the Dobereiner triad. Law of triads: According to Doberein, the arithmetic mean of the atomic masses of the first and third elements of a triad is approximately equal to the atomic mass of the second element of that triad, if the elements are arranged in ascending order of their atomic masses. He also suggested that this law should also apply to other properties of the elements.
One of these properties was density. The atomic mass of cobalt corresponds approximately to the arithmetic mean atomic mass of iron and nickel, which is 57.25. (atomic mass of calcium + atomic mass of barium) / 2 = (40 + 137) / 2 The atomic mass of sodium = (atomic mass of lithium + atomic mass of potassium) / 2. The Doberan triad, composed of halogens, consisted of chlorine, bromine and iodine. Arithmetic mean of atomic weights of calcium and barium = (40+137)/2 = 88.5 What are the disadvantages of the law of the Doberian Triad? The arithmetic mean atomic masses of sulfur and tellurium is 80, which is very close to the atomic mass of selenium.
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