chemistry for grade 7

1. The properties of an element in the periodic table mainly depend on its outer electronic configuration, except in the case of transition elements. 2. Each period begins with an element having only one electron in the valence shell and ends with an element in which the valence shell is complete..

Chlorine belongs to the 'halogen' family. All the elements of this family are non-metals. They exhibit similar properties and they all form salts similar to sodium chloride. All the members of the group VII A are highly reactive, and they are not available in nature in the free state. It can be not..

Longest chain consisting of six carbon atoms..

Chlorine atom has seven valence electrons. Thus, each Cl atom requires one more electron to acquire the nearest noble gas configuration (Ar:2, 8, 8). They do this by mutual sharing of one pair of electrons as shown below...

The electronic configuration of atom 'D' has seven electrons in the outermost shell. Each 'D' atom should share a pair of electrons with another 'D' atoms to form a substance containing only 'D' .i.e., Hence, the formula of the substance is D 2 . It is a covalent compound. ..

The value of any physical quantity is always expressed as its numerical value as well as a unit. One often hears the weight expressed as grams or kilograms; the distance as foot, yard or mile; the volume as litres or gallons. The use of a number of units cause confusion and complications. Hence, th..

S.I. Units - The value of any physical quantity is always expressed as its numerical value as well as a unit. One often hears the weight expressed as grams or kilograms; the distance as foot, yard or mile; the volume as litres or gallons. The use of a number of units cause confusion and complicatio..

Mendeleev's Periodic Law - Later, Mendeleev arranged the sixty-three elements known at that time in the increasing order of the atomic masses, in the form of a table called the Periodic Table. The periodic table further classified the elements by arranging the elements with similar properties toget..

An internal combustion engine works with a system of pistons. A mixture of air and petrol vapor, is drawn from the carburetor into the cylinder in the down-stroke of the piston. In the upstroke phase, the mixture is compressed. The ratio of the initial volume to final volume is called the compress..

The elements placed in group VIIA of the periodic table are called halogens. All these elements form salts called halides, e.g. NaCl, NaI, KCl, KI etc. Halogen is an ancient Greek word meaning 'salt producer'. Halogens have seven electrons in their valence shell and so are monovalent. ..