Chemistry

Chemistry

ACIDS, BASES AND INDICATORS

WHAT IS ACIDS, BASES AND INDICATORS?   All the elements in nature fall into three classes: metals, non-metals and gases. Non-metals are also sometimes called metalloids. The compounds formed by combination of the elements can also be classified as organic and inorganic compounds. Organic compounds are formed from a combination of carbon and hydrogen; they are […]

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Chemistry

EVAPORATION AND BOILING

EVAPORATION AND BOILING (LIQUID TO GAS) On heating particles gain kinetic energy and move faster. In evaporation and boiling the highest kinetic energy molecules can ‘escape’ from the attractive forces of the other liquid particles. The particles lose any order and become completely free to form a gas or vapour. Energy is needed to overcome

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Chemistry

CAREERS IN CHEMISTRY

Chemists are the people who transform the everyday materials around us into amazing things. Some chemists work on cures for cancer while others monitor the ozone protecting us from the sun. Still others discover new materials to make our homes warmer in the winter, or new textiles to be used in the latest fashions. The

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Chemistry

CHEMICAL PROPERTIES OF CARBON

CHEMICAL PROPERTIES OF CARBON The combustion of carbon: Carbon reacts with oxygen to form two oxides, carbon dioxide, CO2, and carbon monoxide CO. The proportions of these two oxides formed during combustion depend on the conditions. At about 500 ºC, carbon dioxide is produced almost exclusively, provided that oxygen is in excess: C(s) + O2(g)

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Chemistry

AMORPHOUS CARBON

AMORPHOUS CARBON Apart from diamond and graphite, which are crystalline forms of carbon, all other forms of carbon are amorphous allotropes of carbon. Coke Coke is the amorphous allotrope of carbon, which is derived from coal. When coal undergoes destructive distillation, it yields two allotropes of carbon, namely coke and gas carbon. Destructive distillation is

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Chemistry

GRAPHITE

What is graphite? Unlike the tetrahedral arrangement of atoms in diamond, the carbon atoms in graphite are arranged in the form of hexagonal rings in layers (Fig.10.2). Each carbon is bonded to only three other carbon atoms in that layer. Different layers of graphite are held together by rather weak forces. Hence they can slide

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Chemistry

DIAMOND

DIAMOND What is diamond? Diamond is the purest form of natural carbon. It occurs as small crystals embedded in rocks. These are supposed to have been formed by the crystallization of carbon under extreme pressure and temperature in the interior of the earth. Nowadays, synthetic industrial diamonds are being manufactured by subjecting graphite to very

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Chemistry

ELECTRODE REACTIONS

Cathode reactions (reduction) (-) negative cathode where reduction of the attracted positive cations is by electron gain (reduction) to form metal atoms or hydrogen [from Mn+ or H+, n = numerical charge]. The electrons come from the positive anode. Hydrogen ions are reduced to hydrogen gas molecules. Electrolysis of many dilute salts or acid solutions

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Chemistry

ELECTROPLATING

Electroplating is a process of depositing a thin layer of a fine and superior metal (like chromium, zinc, nickel, gold etc.) over the article of a baser and cheaper metal (like iron, copper, brass), with the help of electric current. Uses Electroplating is very useful because of the following reasons:   Surface protection e.g. nickel

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Chemistry

ELECTROLYTES AND NON-ELECTROLYTES

However, if the compound is unable to ionise it does not conduct electricity it is called a non-electrolyte. In general, the extent to which an electrolyte can break up into ions categorises an electrolyte. This gives a measure of the degree of dissociation (a) of an electrolyte. Based on this degree the electrolytes can be

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Chemistry

SALTS

General Preparation of Salts Salts are generally ionic compounds formed by the reaction of an acid with a base. The preparation of these salts involves the treating of different metals and non-metals and their compounds with various acids, bases etc. However, some of them can be prepared by direct combination of the concerned elements or

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Chemistry

BONDING IN METALS

Bonding in metals Metal atoms have relatively few electrons in their outer shells. When they are packed together, each metal atom loses its outer electrons into a ‘sea’ of free electrons (or mobile electrons). Having lost electrons, the atoms are no longer electrically neutral.   They become positive ions because they have lost electrons but

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Chemistry

THE PHYSICAL PROPERTIES OF DIAMOND

Diamond Has a very high melting point (almost 4000°C). Very strong carbon-carbon covalent bonds have to be broken throughout the structure before melting occurs. Is very hard. This is again due to the need to break very strong covalent bonds operating in 3-dimensions. Doesn’t conduct electricity. All the electrons are held tightly between the atoms,

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Chemistry

COVALENT BONDING – SINGLE BONDS

COVALENT BONDING As well as achieving noble gas structures by transferring electrons from one atom to another as in ionic bonding, it is also possible for atoms to reach these stable structures by sharing electrons to give covalent bonds.   Depending on the number of electron pairs shared between atoms which participate in bonding, covalent

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