Question

Why are elements used as compounds?

explain why the elements of groups 1 and 7 are mostly used as compounds.

thanks. :)

Answers

Assuming that you mean group1 Na, K etc and group7 F, Cl, etc.

It has to do with the number of electrons in the outer shell.

group 1 elements need to gain one electron to fill their outer shell (become stable)

group 7 elements need to lose one electron to have a full outer shell (become stable)

#1

why is the sea seen as blue

#2

thank you darling

#3

the elements in group 1 and 7 have charges. the alkali metals in group 1 have a valency of +1 (one electron in the outer shell). the halogens on the other hand have a valency of -1 (one electron missing from outer shell). therefore the atoms need to become stable by having full outer shells, either by gaining or losing electrons. in the case of sodium chlride (NaCl) the Sodium has 1 electron to give away, the chlorine has space for another electron. the two elements combine as the outer shells of each are made complete. you can predict the formula for almost any compound. if i used a group 2 alkali earth metal such as magnesium, when combining with another halogen e.g bromine, the formula would be MgBr2. why? the magnesium has a valency of two (its in group 2) so you need two bromines to complete each others outer shells.

#4

btw i am a 16 year old chemistry student!

#5

Group I and VII elements are extremely reactive, so they're usually encountered in compounds - storing and handling them as elements is tricky and generally dangerous, which gives you some idea why they're never encountered as elements "in the wild"

#6

the elements in group 1 and 7 have charges. the alkali metals in group 1 have a valency of +1 ( one electron in the outer shell) . the halogens on the other hand have a valency of -1 ( one electron missing from outer shell) . therefore the atoms need to become stable by having full outer shells, either by gaining or losing electrons. in the case of sodium chlride ( NaCl) the Sodium has 1 electron to give away, the chlorine has space for another electron. the two elements combine as the outer shells of each are made complete. you can predict the formula for almost any compound.

#7