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What best explains the atomic radii decreasing as we move across a period.

The familiar phenomenon of a rainbow results from the diffraction of sunlight through raindrops. Which of the following colors would have the lowest frequency?

We calculated reaction enthalpies based on the average bond enthalpies for the bonds broken in the reactants and the bonds formed in the products. What must be true for a reaction to be exothermic?

The first ionization energy for Al is 578 kJ/mol compared to 738 kJ/mol for Mg which is contrary to the trend that the first ionization energy increases moving across a period. Which is the best explanation for this observation?

Which group has the lowest electron affinity on the periodic table?

Rank the atomic radii from smallest to largest for Mn, K, Ni, Br.

One type of sunburn occurs on exposure to UV light of wavelength in the vicinity of 325 nm. What is the energy of a mole of these photons in kJ/mol? Given the speed of light (c) is 2.99 x 108m/sec, c = λν, 1 nm = 1.0 x 10-9 m, E = hν, Planck’s constant is 6.626 x 10-34 J/sec and a mole = 6.022 x 1023 photons.

What subshells hold the valence electrons for phosphorous?

Calculate the effective nuclear charge, Zeff, for sulfur which has 16 protons given Zeff = Z – S where Z is the atomic number and S is the number of shielding electrons. Hint: writing the electron configuration can help determine the number of shielding electrons.

The placement of the electrons in the 3p-orbital in question #15 follows which rule or principle?