posted by lyne on .
Ca + Br2 --> CaBr2
its synthesis and the reason the reaction happens is stable electron configuration but i don't understand why.
chemistry - DrBob222, Wednesday, January 21, 2009 at 10:06pm
Synthesis because it's two elements combining to form a single product. Stable electron configuration because
Ca has two electrons as the metal (solid). It wants to give those two electrons up and if it does, then the last shell has 8 electrons in it (it is 1s2 2s2 2p6 3s2 3p6 4s2 as the metal. Losing the 2 4s electrons leaves it with 8 in the 3rd shell.) Bromine, as the element, has 7 electrons in its outside shell. It wants to gain 1 electron to make 8. So 1 Ca atom combines with 2 Br atoms, giving 1 electron to each Br, to make CaBr2. The Ca is now a +2 ion and the 2 Br atoms are Br^- ion. This is a typical ionic bond.
chemistry - lyne, Wednesday, January 21, 2009 at 10:09pm
okay but doesnt this happen in a lot of the synthesis ones then?
2Na + Cl2 ==> 2NaCl
Ca + Cl2 ==> CaCl2
2Mg + O2 ==> 2MgO
H2 + Cl2 ==> 2HCl (BUT this one shares electrons so that H has two and Cl has 8). HCl gas is a covalent compound and not ionic. Actually, its a polar covalent compound.
oh okay i get it!!
2Cs (s) + NiSO4 (aq) --> Cs2SO4 + Ni
is activity series
i understand the equation but not how it is activity series
Single replacement reaction. Cs is above Ni in the activity series; therefore, Cs replaces Ni^+2 to form Cs2SO4 + Ni(s). Any other metal above Ni in the activity series would have the same reaction. Any metal below Ni (Cu, Ag, etc) would not replace Ni and there would be no reaction.
thanks sooo much i totally get it now wow thanks again :)