In my book, the first reason mentioned is that there is a slight increase in effective nuclear charge down a group, which increases electron affinitiesI know that with more protons, there is a stronger magnet, or nuclear charge that holds the electrons closer together, but I don't understand what this reason really means.The 2nd reason is an cinrease in atomic radius down a group, which decreases electron affinities, as the size effect predominatesI don't understand this either/Also, my last question, in my book it says that gallium has a slightly smaller atomic radius than does aluminum, since gallium is preceded in its period by 10 d-block elementsWhat does this have to do with it? Usually, elements with higher occupied energy levels have a larger radius?? well please help! D
If it was my house, I think that I would paint the aluminumVinyl doesn't last as long as aluminum.
The trouble with painted aluminum siding is that the paintjob will eventually wear out just like painted woodVinyl siding suggests that the job was done more recently than the painted aluminum which really isn't done anymore.
1Your book is saying, that while there is a slight increase in Effective Nuclear Charge, it is small, and the decrease in electon affinity is better explained by your 2Effective Nuclear Charge is the charge the electron feels from the nucleusThe more electrons in orbitals underneath the outer electron, the more the outer electron is shielded from the nuclear charge by the inner electronsElectrons in the same energy level cannot shield each otherAs you go down in a group, the more and more suborbitals there are, p, then d, then fThe electrons repel each other and spread out as much as possible, allowing more of the nuclear charge to shine through, i.e., Effective Nuclear Charge becomes larger2This is a q1, q2 situationdE (q1 xq2)/ r^2, where r is the distance between the two charged particlesThe further they are from each other (r^2 becomes greater), the lower the dE between themq1 and q2 are oppositely charged particles3Ga has a completely filled 3rd energy level, which results in a lower energy for that orbitalIt collapses in on itselfThe number of protons in the nucleus is greater by the number of d orbitals, with a higher Effective Nuclear Charge than Al.
