11- Explain each of the following observations using principles of ATOMIC STRUCTURE or BONDING.?

Question

a) Potassium has a lower first-ionization energy than lithium.

b) The ionic radius of N (3-) is larger than that O (2-)

c) A calcium atom is larger than a zinc atom

d) Boron has a lower first ionization energy than Beryllium

helpp with this ! its not HARD

Answer 1

If it is not hard, you should be able to answer it. :-)

a) the last electron in Li is only shielded from the nucleus by two other electrons, so it feels essentially a full +1 charge keeping it attached. the last electron in K is shielded from the nucleus by 18 other electrons, the effective nuclear charge experienced by this electron is less than +1 and consequently it is easier to take it off.

b) N is trying to control 10 electrons with only 7 protons in the nucleus while O is trying to control 10 electrons with 8 protons in the nucleus. Replace the elements with day-care givers and the electrons with unruly three-year olds and you might see why the first is harder to control and the electrons occupy a larger volume.

c) Ca and Zn have the same principal quantum number (4) so this sets the maximum volume that can be occupied by the electrons. Ca has 20 protons controling 20 electrons in this volume while Zn has 30 protons controling 30 electrons in the same permissible volume. The attraction of 30 protons serves to hold the electrons tighter and thus shrink the volume or radius of the atom.

d) If Be loses an electron it goes to a half-full s orbital while if B loses an electron it goes to a full s orbital, a more stable arrangement than the half-full orbital.

Chemists have 20/20 hind sight!