Define mass and write its SI unit? Calculate the number of atoms in 52 moles of Ar and 52 g of He. What is the mass per cent of elements present in Na2SO4 What is the difference between 0.50 mol Na2CO3 and 0.50 M Na2CO3
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Laws Of Chemical Combination
There are five basic laws that govern the chemical combination of elements. They are as follows: Law of Conservation of Mass It states that during a chemical reaction, the mass of the products and reactants will always be equal. Law of Definite Proportions It states that every chemical compound will contain a fixed and constant… Continue reading Laws Of Chemical Combination
Introduction
Chemistry is referred to as the “Central Science” as it interconnects geology, biology, environmental science, and physics to each other. Ancient Indians had knowledge of various concepts from chemistry even before it emerged as a discipline. In chemistry, one of the core fundamental concepts is matter – it is defined as a substance that occupies… Continue reading Introduction
Trends in the Modern Periodic Table
Trends in Modern Periodic Table In a group – Elements have the same number of valence electrons. Down the group – number of shells increases. In a period – Elements have the same number of shells. Along the period – valence shell electrons increase by one unit. Variation of Valency Valency of an element can… Continue reading Trends in the Modern Periodic Table
Classification of Modern Periodic Table
The modern periodic table is also classified into metals, non-metals and metalloids. Metals Metals are electropositive as they form bonds by losing electrons. In general cases, oxides of metals are basic in nature. Examples: Includes iron, copper, silver, mercury, lead, aluminum, gold, platinum, zinc, nickel and tin. Non-metals Nonmetals are electronegative as they form bonds… Continue reading Classification of Modern Periodic Table
Groups in Modern Periodic Table
The modern periodic table contains 18 vertical columns known as groups. Group 1 elements are known as alkali metals.Group 2 elements are known as alkaline earth metals.Group 15 elements are known as pnicogens.Group 16 elements are known as chalcogens.Group 17 elements are known as halogens.Group 18 elements are known as noble gases. Alkali Metals The… Continue reading Groups in Modern Periodic Table
Periods in Modern Periodic Table
Elements present in the same period have the same number of shells which is equal to the period number. A period is a row of the periodic table that is horizontal. The periodic table contains seven periods, each of which starts at the left. On moving from left to right in a given period, the number of… Continue reading Periods in Modern Periodic Table
Modern Periodic Table
In the past, scientists believed that an element’s qualities were periodic functions of its atomic mass. Mendeleev arranged 63 elements in a vertical column named groups and horizontal rows called periods based on this idea. This approach was disregarded since it was unable to account for the locations of several elements, rare earth metals, and… Continue reading Modern Periodic Table
Mendeleev`s Periodic Table and Law
The physical and chemical characteristics of elements are a periodic function of their atomic masses, in accordance with Mendeleev’s Periodic Law. Mendeleev organised the elements in ascending order of their atomic masses after classifying them according to their atomic masses. The physical and chemical properties of elements are periodic functions of their atomic weights. Features… Continue reading Mendeleev`s Periodic Table and Law
Early Models of Periodic Table
Dobereiner’s Triads Dobereiner arranged a group of three elements with similar properties in the order of increasing atomic masses and called it a triad. He showed that the atomic mass of the middle element is approximately the arithmetic mean of the other two. But, Dobereiner could identify only the following three triads from the elements known at that time.… Continue reading Early Models of Periodic Table