Account for the large decreases in electron affinity between Li and Be despite the increases in nuclear charge.

Screening effect is the effect produced by intervening electrons between nucleus and valence electrons . They shield the nucleus from valence electron and effective nuclear charge decreases if there is less shielding effect the effective nuclear charge decreases Valence electrons are attracted by nucleus and repelled by other electrons. Net effective force on electrons under consideration = Z-sigma = (Nuclear charge -screening effect ) slaters formula for screening constant. If one electron is present in outermost orbit there will be no screening in that orbital. Each electrons contributes 0.35 (total electrons minus 1) present in outermost shell. In penultimate energy level electrons contribute 0.85. A contribution of 1 is from remaining electrons (present in last but one energy level) The effective nuclear charge for 4s electrons of Zn will be

Write differences between electronegativity and electron affinity.

If the average distance between the sun and the earth decreases for some reason , then state whether the length of a year will increase or decrease. Give the reason for your answer .

In any nuclear reaction - (A) The total number of protons and neutrons remains same before and after the reaction. (B) Increase or decrease in the number of protons is equal to the decrease or increase in the number of neutrons. (C) Kinetic energy of the incident particle is approximately 8 MeV or its equivalent. (D) Some energy is released if total mass is reduced.

In Young's experiment for the interference of light, the separation between the slits is d and the distance of the screen from the slits is D. If D is increased by 0.5% and d is decreased by 0.3%, then for the light of a given wavelength, which one of the following is true ? "The fringe width.........."

Statement I: In spite of increasing in doping level the conductivity of the semiconductor does not change. Statement II : By increasing in doping level the conductivity the concentration of one type of charge carriers (electrons or holes ) is increased and at the same time concentration of other charge carrier decreases.

The bromine atom possesses 35 electrons. It contains 6 electrons in 2p orbital. 6 electrons in 3p orbital and 5 electron in 4p orbital. Which of these electron experiences the lowest effective nuclear charge?

Coulomb’s law for electrostatic force between two point charges and Newton’s Law of gravitational force between masses depends on the distance between the charges/ masses. (b) Estimate the accelerations of electron and proton due to the electrical force of their mutual attraction when they are 1overset@A(=10^(-10)m) apart? (m_p=1.67x10^(-27)kg,m_e=9.11x10^(-31)kg)

The unpaired electrons in Al and Si are present in 3p orbital. Which electrons will experience more effective nuclear charge from the nucleus?