General Chemistry

1. In the spectrum of hydrogen atom, the series which falls in ultraviolet region is_______ (a) Lyman series (b) Balmer series (c) Paschen series (d) Brackett series Answer. (a) 2. The e/m value for the particles constituting cathode rays is the same regardless of_______ (a) the gas present in cathode …

De Broglie Equation – de Broglie had arrived at his hypothesis (de Broglie equation) with the help of Planck’s Quantum Theory and Einstein’s Theory of Relativity. – He derived a relationship between the magnitude of the wavelength associated with the mass (m) of a moving body and its velocity. – …

Zeeman Effect – In 1896 Zeeman discovered that spectral lines are split up into components when the source emitting lines is placed in a strong magnetic field. It is called the Zeeman effect after the name of the discoverer. – The apparatus used to observe the Zeeman effect is shown …

– The Bohr-Bury scheme considers that the maximum number of electrons that each orbit can contain is 2 × n2, where n is the number of orbits. – Having known that planetary electrons numerically equal to the atomic number are revolving about the atomic nucleus in closed orbits, the question …

– Bohr theory was based on Planck’s quantum theory and was built on some postulates. – Rutherford’s nuclear model simply stated that atom had a nucleus and the negative electrons were present outside the nucleus. – It did not say anything as to how and where those electrons were arranged. …

– In this subject, we will discuss the Photoelectric Effect and Compton Effect Photoelectric Effect – When a beam of light of sufficiently high frequency is allowed to strike a metal surface in a vacuum, electrons are ejected from the metal surface. – This phenomenon is known as the Photoelectric …

– In this subject, we will discuss the atomic Spectrum of Hydrogen Atomic Spectrum – When an element in the vapour or the gaseous state is heated in a flame or a discharge tube, the atoms are excited (energised) and emit light radiations of a characteristic colour. – The colour …

– In this subject, we will discuss the Atomic Number and Mass Number Mosley’s Determination of Atomic Number – The discovery that an atom has a nucleus that carries a positive charge raised the question: What is the magnitude of the positive charge? – This question was answered by Henry …

– In this subject, we will discuss the Rutherford’s Atomic Model (Experiment, Postulates, weakness) Alpha particles – Alpha particles are shot out from radioactive elements with very high speed. – For example, they come from radium atoms at a speed of 1.5 × 107m/sec. – Rutherford identified them to be …

– In this subject, we will discuss the Subatomic Particles: Electrons, Protons, and Neutrons Subatomic Particles – We have hitherto studied the properties of the three principal fundamental particles of the atom, namely the electron, proton, and neutron. – These are summarised in this Table:   – Nearly all of …

Cathode Rays – The discovery of electron – The knowledge about the electron was derived as a result of the study of the electric discharge in the discharge tube (J.J. Thomson, 1896). (1) The discharge tube consists of a glass tube with metal electrodes fused in the walls. (2) Through …

– In this subject, we will discuss the Kinetic Molecular Theory of Gases. Introduction to The Kinetic Molecular Theory – The gas laws help us to predict the behavior of gases, but they do not explain what happens at the molecular level to cause the changes we observe in the …

– Before you solve these problems, you can read this subject for Dalton’s Law of Partial Pressures (Statement, Mathematical, Importance, Application). – Let us understand Dalton’s law by solving these problems. Solved Problems on Dalton’s Law  Problem (1) on Dalton’s Law A mixture of oxygen and neon contains oxygen at …

– In this subject, we will discuss Dalton’s Law of Partial Pressures (Statement, Mathematical, Importance, Application). Dalton’s Law of Partial Pressures – Thus far we have concentrated on the behavior of pure gaseous substances, but experimental studies very often involve mixtures of gases. – For example, for a study of air …

– In this subject, we will discuss the Density of gas (Definition, Equation, Solved Examples) The Density of gas – From the ideal gas equation: – If we rearrange the ideal gas equation, we can calculate the density of a gas: – The number of moles of the gas, n, …

– In this subject, we will discuss the Molar Mass of gas (Definition, Equation, Solved Examples) The Molar Mass of a gas – From what we have seen so far, you may have the impression that the molar mass of a substance is found by examining its formula and summing …

– In this subject, we will discuss the Relationships between Structure and Acidity. – The strength of a Brønsted–Lowry acid depends on the extent to which a proton can be separated from it and transferred to a base. – Removing the proton involves breaking a bond to the proton, and …

– In this subject, we will discuss How to Predict the Outcome of acid-base reaction. How To Predict the Outcome of acid-base reaction – The following table gives the approximate pKa values for a range of representative compounds. – While you probably will not be expected to memorize all of the …

– In this subject, we will discuss the Orbital Representation of some Molecules (1) Orbital Representation of H2 molecule – Each hydrogen atom has one electron in 1s-orbital. – Two such atoms join to form a molecule of hydrogen. – In this case s–s overlapping between two 1s-orbitals of hydrogen …

– In this subject, we will discuss Solved Problems on The Ideal gas law  Problem (1) on The ideal gas law  Calculate the volume of a sample of gas originally occupying 908 mL at 717 torr and 20 oC after its temperature and pressure are changed to 72 oC and …