Please help me on my home work. Thanks!!

1. Why do members of the same vertical group of the periodic chart tend to show similar chemical and physical properties?

2. In comparing the vigor of the reactions of lithium, sodium, and potassium with cold water, does there appear to be a correlation between the location of these elements in the periodic table and the vigor reaction?

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Well, what do you think? Do you want help in thinking about these things or just the answers?

Part one; if you look at the electron configuration of say group 18 they all have completely filled orbitals; no wasted space; group 1 all have a single electron in a great deal of open space, while group 2 have two spare electrons; group 14 all have 4 spare electrons. Since group 18 have all the electrons they will ever want, these elements don't often go in search of them, and when they get extras, they give them up just as easily. If the ideal is 8, then group 17, with 7 outer electrons is just dying to snatch an extra electron, so they are greedy and latch onto neighboring electrons; consequently, they are highly reactive and can only be isolated (made in pure form) with lots of energy (ie through electrolysis or really reactive reagents. group 14 can give up the 4 or snatch another 4, so they swing both ways. You will notice that in group 14 C graphite is brittle but conducts electricity almost like a metal, Ge is more metallic but still brittle; Sn is soft and looks like a metal, but if you bend it, it screams because it remembers it's really a semimetal; Pb is soft and bends and never screams; as you go down you have more and more electrons and this cloud of electrons makes the stuff seem more metallic.

If you think about this, you should be able to answer part two. Doesn't your chemistry book explain this? Did you try reading the Britannica article on the Periodic Law?

Re: Please help me on my home work. Thanks!!

[quote="binoo"]1. Why do members of the same vertical group of the periodic chart tend to show similar chemical and physical properties?

2. In comparing the vigor of the reactions of lithium, sodium, and potassium with cold water, does there appear to be a correlation between the location of these elements in the periodic table and the vigor reaction?[/quote]

Or in general, you can say for :
q1: The number of electrons in outermost shell is the same so they have the same chemical properties.
q2 yes, the number of occupied shells increase down the group. so the attraction force is decreased down the group. The element at the bottom of the periodic table is easier to lose electron and react with the water.

Feel free to reply if there is any problem in my answer.

[color=darkgreen]Actually, I think that the second question would be more of a note of how far the electrons are from the nucleus of each of the elements. Potassium's outer shell is a lot larger than that of lithium, so there is less force pull exerted on the electrons from the protons in the nucleus. Less force exerted means less energy to pull the electons off.[/color]

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