Notes and Study material for Exams
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 … Read more
Chemical Bonding and Molecular Structure The smallest particle of element is atom and the smallest particle in a compound is molecule. The force or the binding that keeps the atoms in the molecule combined during the formation of molecule is called chemical bonding. The concepts like that of Kossel-Lewis, VSEPR principle, valence bond theory, molecular … Read more
Periodic Table and periodicity Criteria for a new element discovery Assessing if an element has been “discovered” is not a simple task. While reviewing the discovery profiles of the transfermium Elements in the early 90s’, IUPAC and IUPAP set up to establish a series of criteria that must be satisfied for the discovery of an … Read more
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 … Read more
Microscope Microscope, instrument that produces enlarged images of small objects, allowing the observer an exceedingly close view of minute structures at a scale convenient for examination and analysis. Although optical microscopes are the subject of this ARTICLE, an image may also be enlarged by many other wave forms, including acoustic, X-ray, or electron … Read more
Valency Valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or Molecules. The combining power, or affinity of an atom of a given element is determined by the number of hydrogen atoms that it combines with. In methane, carbon has a valence of 4; in … Read more