Shikshakendra

Clearly, chlorine requires one more electron to acquire the stable noble gas electronic configuration. In order to become stable, hydrogen and chlorine will share one electron with each other. This allows hydrogen atom to attain its duplet and chlorine to attain its octet. The electron dot structure of hydrogen chloride molecule is shown in fig. 4.3. Further, since chlorine atom and hydrogen atom share one electron to form HCL molecule, thus, valency of HCL is 1. That is, HCL is also monovalent.    (iv) Formation of Ammonia Molecule, NH3:  Atomic number of nitrogen = 7         Electronic configuration = K  L                                                       2  5 Clearly, nitrogen has 5 electrons in its outermost shell, i.e., l  shell and thus, requires one more electron to atta...

  ~ Types of Covalent Bonds  The covalent bonds are of three types :  (i) If each atom contributes one electron then the covalent bond formed is called a single  covalent bond which is represented by a single  line (-). (ii) If each atom contributes two electrons, then the covalent bond formed is called a  double bond which is represented by a double  line. (iii) If each atom contributes three electrons, then the covalent bond formed is called a    triple bond which is represented by a triple  line.  ~ Formation of Covalent Bonds  We shall now discuss formation of some simple molecules formed by sharing of valence electrons (i) Formation of Hydrogen Molecules, H2 : The atomic number of hydrogen is 1. Hence, Hydrogen has one electron in its K shell and it requires one more electron to fill the K shell. So the two hydrogen atoms share their electrons to form a molecule of hydrogen, H2. This allows each hydrogen atom to attain the...

  ~ INTRODUCTION  Carbon is a unique element. It is a non-metal with symbol C. Carbon gets its name from the Latin word Carbo , which means a black rock that can burn. Carbon exists in nature in many forms.  The carbon compounds are also known as organic compounds.  Besides this, a large number of things we use or consume in our everyday life are made up of carbon compounds. For example, our food materials like grain, pulses, fats, sugar, coffee, fruits and vegetables, etc., are made up of carbon compounds. The fuels such as wood, coal, kerosene, LPG (liquefied Petroleum gas), natural gas, CNG (compressed natural gas), petrol and diesel, etc., which we used to cook our food and to run vehicles are made up of carbon compounds.  The carbon is a versatile element. The amount of carbon present in the earth's crust and in the atmosphere is quite meagre. The earth's crust has only 0.02% carbon in the form of minerals (like carbonates, hydrogencarbonates, coal, petrole...

  LIFE PROCESSES      Chapter at a Glance  1. The various life processes which takes place in the living organisms are called metabolic activities or metabolism. This life processes can either be anabolic or catabolic in nature.  2. Nutrition, respiration, transportation and excretion are some of the life processes that are essential for the functioning as well as maintenance of living organisms. 3. Energy is needed to maintain a state of order in any living organism. 4. Nutrition is defined as a process by which living organisms procure food or synthesise it and convert it into simple absorbable formed by a series of biochemical processes. 5.  Nutrient can be defined as the the substance which an organism obtains from its surrounding and use it as a source of energy as well as provides raw materials for the biosynthesis of body constituents. 6. There are two basic modes of nutrition :  autotrophic and heterotrophic. 7. In autotrophic nutrition o...