valency (values)

At high temperature, electrons move from valance band to conduction band and as a result a vacancy is created in the valence band at a place where an electron was present before shifting to conduction band. The valency is a hole and is seat of positive charge having the same ..

Distinction between the three in terms of energy bands - The electrons in the valence band are not capable of gaining energy from external electric field and hence do not contribute to the current. This band is never empty but may be partially or completely with electrons. On the contrary..

Due to their low ionization energies all group 2 elements tend to lose their valence electrons and act as strong reducing agents. The decrease of the reduction potential values down the group, indicate an increase of strength as a reducing agent. However the members of this gro..

. The total energy of the system is equal to the sum of the energies of the two H atoms. When the two atoms approach each other, electrons of one atom attract the nucleus of the other atom. Electrons of both the atoms are attracted by both the nuclei. These attractive interactions lead to a decreas..

Atomic radii in general, decrease with increase in atomic number, going from left to right in a period. This is explained on the basis of increasing nuclear charge along a period. The nuclear charge increases progressively by one unit while the corresponding addition of one electron takes place in..

Anomalous Behavior of Oxygen - Like all other first elements of the groups, oxygen also differs from its family members. The anomalous behavior of oxygen is due to its (i) small size (ii) high value of ionization energy and electronegativity (iii) absence of d-orbitals in the valence..

Intermolecular Forces and Interatomic Forces - When two wet glass plates are pressed together, they cannot be separated easily. This is because of the force of attraction existing between the atoms and molecules, and are electrical in origin. As the two isolated Hydrogen atoms approach each other, ..

. According to Mendeleev's periodic law, the physical and chemical properties of elements are periodic functions of their atomic mass Mendeleev was able to predict the existence of undiscovered elements like Ga, Sc and Ge Mendeleev corrected the atomic masses of a few elements on the basis of their..

Alkali metals have the lowest ionization energy in each period. Within the group, as we go down, the ionization energies of alkali metals decrease due to their atomic size being the largest in their respective periods. In large atoms the valence electrons are loosely held by the nucleus..

fig 7.11 - Layers of ions surrounding a charged particle of iron (III) hydroxide.A: Fe(OH) 3 surrounded by Cl - ionsB: Fe(OH) 3 surrounded by PO 4 3- ions If the ion layer is gathered close to the colloidal particles, the overall charge is effectively neutralized and two colloidal particles can app..