Excretory System
The main excretory organ of human is kidney and skin. Kidney is a bean shaped organ, which lies in the abdominal cavity one on each side of the vertebral column. Each of them is about 10 cm long and 150g in weight. It is enclosed in a thin, fibrous covering called the capsule. A renal artery brings blood into the kidney along with nitrogenous waste materials, which after filtration in the kidney leaves the kidney through a renal vein. The outer region of kidney is called cortex and inner region is called medulla. Each kidney is made up of numerous coiled excretory tubules, called nephrons. A nephron is the structural and functional unit of kidney. It performs three functions, such as, filtration, reabsorption and secretion. A nephron consists of a long tubules and the Malpighian corpuscle. The proximal more...
Transportation
Transportation in Plants
There are two types of vascular tissues in plants that helps in transportation of materials. These vascular tissues are xylem and phloem. The xylem tissues are present in roots of the plant and the phloem tissues in their shoot system Water and minerals are taken from the soil and transported to the upper part of the plant through xylem tissue. This transport of nutrient from one part of plant to other part is called translocation. The xylem tissue consists of vessels and tracheids, which carries water and minerals to all parts of the plant. This transport of water and dissolved mineral salt from the roots to the leaves is known as ascent of sap. The pressure with which water is pushed into the more...
Respiration
All the living organisms requires energy for their life processes. They derive this energy from the food they eat. The respiration is the process of breaking down of complex food molecules into simpler form with the release of energy. It is of two types, aerobic and anaerobic respiration. The respiration which takes place in presence of oxygen is called aerobic respiration and the respiration which takes place in absence of oxygen is called anaerobic respiration.
Anaerobic Respiration
The respiration, which takes place in absence of oxygen or with limited supply of oxygen is called anaerobic respiration. In this process, the sugar molecule is broken down into simpler form either in absence of oxygen or with the limited supply of oxygen. It takes place in the cell which lacks mitochondria. In more...
Introduction
We see the variety of things around us in which some are living and some are non living. All the living organisms have organized cellular structure with different levels of organization. An organized and ordered structure with cells, tissues, organs, organ system, is an important feature of living organism that distinguishes it from non living organisms. If this organization break down then the organism is no longer living. The maintenance functions of living organisms must go on forever to sustain life. The process which together performs this maintenance job are called life process. The life process needs energy, which mostly comes from the plants and trees. The outside source of energy is varied, as the environment is not in our control. So these sources of energy is needed to be broken down or built up inside our body. The process of more...
Modern Periodic Classification
Periodic Law
'Properties of elements are a periodic function of their atomic number Atomic number gives us the number of protons in the nucleus of an atom and this number increases by one in going from one element to the next. Elements, when arranged in order of increasing atomic number Z, lead us to the classification known as the Modern Periodic Table. Prediction of properties of elements could be made with more precision when elements were arranged on the basis of increasing atomic number.
Position of Elements in the Modern Periodic Table:
The Modern Periodic Table has 18 vertical columns known as 'groups' and 7 horizontal rows known as 'periods'. Let us see what decides the more...
Mendeleeu's Classification
In 1869, a Russian chemist, Mendeleev, on the basis of physical and chemical properties discovered a relation known as "PERIODIC LAW". "The properties of element are the periodic function of their atomic masses".
| Group | I | II | III | IV | V | VI | VII | VIII |
| Oxide Hydride | R2O RH | RO RH2 | R2O3 RH3 | RO2 RH4 | R2O5 RH3 |
Newland's Classification
Newlands' Law of Octaves The attempts of Dobereiner encouraged other chemists to correlate the properties of elements with their atomic masses. In 1866, John Newlands, an English scientist, arranged the then known elements in the order of increasing atomic masses. He started with the element having the lowest atomic mass (hydrogen) and ended at thorium which was the 56th element. He found that every eighth element had properties similar to that of the first. He compared this to the octaves found in music. Therefore, he called it the 'Law of Octaves'. It is known as 'Newlands' Law of Octaves'. In Newlands' Octaves, the properties of lithium and sodium were found to be the same. Sodium is the eighth element after lithium. Similarly, beryllium and magnesium resemble each
Dobereiner’s Classification
In the year 1829, Johann Wolfgang Dobereiner, a German scientist, was the first to classify elements into groups based on John Dalton's assertions. He grouped the elements with similar chemical properties into clusters of three, called 'Triads'. The distinctive feature of a triad was the atomic mass of the middle element. When elements were arranged in order of their increasing atomic mass, the atomic mass of the middle element was approximately the arithmetic mean of the other two elements of the triad.
Introduction
So far Scientists have discovered 118 elements. Some of these elements are in free states, while the others in combined state. But all these elements were not discovered in a day. It has taken a long time to do so. When a very few elements were known, study of these elements were easier. But with the increase in the number of elements, it became difficult to study the properties of all of them separately. So an attempt has been made from time to time to classify these elements into groups, depending upon their physical and chemical properties. The study of the properties of element of a particular group helps the scientists to predict the properties of other elements of that group. In this chapter we will discuss about the classification of the elements into various groups on the basis of
Soaps and Detergents
A soap is a sodium salt of long chain fatty acid. A soap molecule consists of along hydrocarbon chain. It composed of carbons and hydrogens, with a carboxylic acid group on one end which is ionic bonded to a metal ion, usually a sodium or potassium. The hydrocarbon end is nonpolar and is soluble in nonpolar substances, such as fats and oils; and the ionic end, the salt of a carboxylic acid is soluble in water. The structure of a soap molecule is represented below:
Non-polar hydrocarbon chain ionic end (soluble in nonpolar substances) (soluble in water)
Detergents are structurally similar to soaps, but differ in the water-soluble portion. Three examples of detergents are shown below. When
