When an atom has more than one electron, the electronic structure of the atom cannot be simply described as the electron-electron repulsion makes solving Schrodinger’s equation very hard. Instead, an approximation is made that the wavefunction of a two electron atom or ion is obtained by assigning each electron to one of the atomic orbitals of hydrogen. This is known … Read more
Shapes of atomic orbitals The wavefunction for a given atomic orbital has a characteristic mathematical expression. The wavefunctions for the l = 0 levels, the s orbitals, depends only on the distance of the electron from the nucleus. These orbitals are therefore spherically symmetric. The mathematical expression for the 1s orbital of Hydrogen is where a is a constant known as the Bohr radius, … Read more
n the description of the energies of transition of the hydrogen atom, the n values for the different energies are known as the principal quantum number for that energy level. Each atomic orbital is described by a set of quantum numbers: the principal quantum number, and three others, the orbital angular momentum quantum number, l, the magnetic quantum number, m, and the spin angular momentum quantum number, s. These … Read more
Most atoms are made up of a nucleus surrounded by Z electrons, where Z, the atomic number, is the charge on the nucleus. The forces in these many-electron atoms include the electrostatic attraction between the electrons and the nucleus, but also electrostatic repulsion between the electrons. The hydrogen atom is special in that it contains only one electron, … Read more
As well as using the hard and soft acid and base description to discuss the interactions, we can look at the thermodynamic properties of the acid-base reaction. The aim is to include electronic, structural rearrangement, and steric effects in a small set of parameters. The standard enthalpy of formation of the product of the reaction … Read more
When we consider general acids such as Al3+, Cr3+, and BF3, we find there are good correlations between the order of affinity to bases obtained with them and the order obtained when H+ is used as the acid. However, a different order is observed for an acid such as Hg2+. We need to consider two … Read more
A strong acid, with pKa<0, is almost completely ionized in aqueous solution. Similarly, a strong base is almost fully protonated in solution. A weak acid, with pKa>0, is not completely ionized in solution, and a weak base is only partially protonated. Note that it is important to distiguish between a weak base which is only … Read more
The strength of a bronsted acid, HA, in aqueous solution is given in term of the acidity constant, Ka (which is also known as the acid ionization constant), where: and a(X) is the activity of species X. The activity of a pure liquid is 1, and in dilute solution the approximation a(H2O) = 1 is … Read more
Types of Acids and Bases: Arrhenius: acids and bases dissolve in water releasing H+ and OH– respectively. This is a narrow categorization. Bronsted-Lowry: an acid is a H+ donor, and a base is a H+ acceptor. This is also a narrow definition, but a very important one. Lux-Flood: an acid is an O2- acceptor, and … Read more
All nitrogen oxides are thermodynamically unstable with respect to decomposition to N2 and O2, but they are kinetically stable, ie. the rate of decomposition is very slow. All the oxides contain Npπ-Opπ bonding. Nitrous Oxide/Dinitrogen oxide (N2O): The oxidation state of N is +1, and this compound is a colourless gas and chemically inert. isoelectronic with CO2 and N3–. The N-N bond order is … Read more