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Metals and Non-metals

Metal   In chemistry, a metal is an element that readily forms positive ions (cations) and has metallic bonds. Metals are sometimes described as a lattice of positive ions surrounded by a cloud of delocalized electrons. The metals are one of the three groups of elements as distinguished by their ionization and bonding properties, along with the metalloids and nonmetals. On the periodic table, a diagonal line drawn from boron (B) to polonium (Po) separates the metals from the nonmetals. Most elements on this line are metalloids, sometimes called semi-metals; elements to the lower left are metals; elements to the ... Read more

Carbon and its compounds

Carbon is the common element found in all known form of life. Structure of all living organism contains carbon. Carbon present in living organism even after death. Coal, petroleum and its products are compounds of carbon. Carbon is an element and a non-metal. Symbol of Carbon = C Atomic number of carbon = 6 Atomic structure of carbon = 2, 4 Valence electrons of carbon = 4 Nature of carbon = Non-metal Since, valency of carbon is equal to four, thus carbon is called tetravalent. Four valency of carbon means, carbon reacts with four atoms of same or different elements ... Read more

Structure of atom

Atomic Structure In 1897 J.J. Thomson discovered electron as a constituent of atom. He determined that an electron had a negative charge and had very little mass as compared to that of the atom. Since an atom was found to be electrically neutral it was inferred that some source of positive charge must be present in the atom. This soon led to the experimentaldiscovery of the proton, which is a positively charged subatomic particle. Proton was found approximately 1840 times heavier than an electron. Further‘ experiments revealed that the atomic masses were more than that expected from the presence of ... Read more

Acids, Bases and Salts.

Acid An acid is a substance which forms H+ ions as the only positive ion in aqueous solution. Examples:- Hydrochloric acid dissolved in water forms H+ and Cl– ions HCl —> H+ + Cl–   Sulphuric acid dissolved in water forms H+ and SO42- ions H2SO4 —>2H+ + SO42-   Nitric acid forms H+ and NO3– ions when dissolved in water HNO3 —> H+ + NO3–   Ethanoic acid,also know as acetic acid, forms H+ and CH3COO– ions in water CH3COOH —> H+ + CH3COO– Acetone, also known as propanone, doesn’t form any ions in water, so it isn’t an acid. CH3COCH3 just dissolves in water. Methane, CH4, doesn’t form any ions in water, so this ... Read more

Fundamental unit of life-Cell

  Objects having characteristics of cellular organization, growth, reproduction, ability to sense environment and give response are living organisms. There are some important features of living organisms: It should grow, which means its structure changes as time goes by in an advantageous manner. It should show adaptation to the environment. It should maintain some balanced conditions in its inner structure. This is called Homeostasis. Its structure is highly organized. It should be able to break down or build up nutrients to release or store energy based on need. This is called Metabolism. It should be able to reproduce itself. Classification ... Read more

Metabolism

Metabolism  is the set of life-sustaining chemical transformations within the cells of organisms. The three main purposes of metabolism are the conversion of food/fuel to energy to run cellular processes, the conversion of food/fuel to building blocks for proteins, lipids, nucleic acids, and some carbohydrates, and the elimination of nitrogenous wastes. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. The word metabolism can also refer to the sum of all chemical reactions that occur in living organisms, including digestion and the transport of substances into and between different cells, in which ... Read more

Reproduction

Reproductive systems The reproductive system in both males and females consists of structures that produce reproductive cells, or gametes, and secrete sex hormones. A gamete is a haploid cell that combines with another haploid gamete during fertilization. Sex hormones are chemical messengers that control sexual development and reproduction. The male reproductive system consists of structures that produce male gametes called sperm and secrete the male sex hormone testosterone The reproductive system is a collection of internal and external organs in both males and females that work together for the purpose of procreating. Due to its vital role in the survival ... Read more

Heredity and Evolution

Evolution, simply put, is descent with modification. This definition encompasses small-scale evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations). Evolution helps us to understand the history of life. Evolution is not simply a matter of change over time. Lots of things change over time: trees lose their leaves, mountain ranges rise and erode, but they aren’t examples of biological evolution because they don’t involve descent through genetic inheritance.  The central idea of biological evolution is that all life on ... Read more

Gravitation

Newton’s law of universal gravitation states that a particle attracts every other particle in the universe using a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Gravitation Gravitation is the force by which every mass or particle of matter, including photons, attracts and is attracted by every other mass or particle of matter.The gravitational field at any point P in space is defined as the gravitational force felt by a tiny unit mass placed at P. Every particle of matter in the universe attracts every ... Read more

Work and Energy

Work energy and power Work is said to be done when a force applied on the body displaces the body through a certain distance in the direction of force.Mathematically, work is the force-displacement product (for those of you who prefer algebra) W = F x s cos a or the force-displacement path integral (for those of you who prefer calculus). dW =F · ds Positive work means that force (or its component) is parallel to displacement. Negative work means that force (or its component)is opposite to displacement i.e. In conservative field work done by the force over a closed loop ... Read more