Ca + Br2 --> CaBr2
its synthesis and the reason the reaction happens is stable electron configuration but i don't understand why.
Responses
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?
sure.
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 :)
Yes, synthesis reactions often involve the combination of two or more elements to form a single compound. The reason behind the formation of compounds in synthesis reactions is to achieve a stable electron configuration.
Atoms are made up of protons, neutrons, and electrons. Electrons are arranged in energy levels or shells around the nucleus of an atom. The first shell can hold a maximum of 2 electrons, while the second and third shells can hold up to 8 electrons each.
In the reaction you mentioned, calcium (Ca) has 20 electrons. Its electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2. Calcium wants to achieve a stable electron configuration like the noble gas argon (Ar), which has 18 electrons. By losing its 2 outermost electrons, calcium can achieve this stable configuration.
On the other hand, bromine (Br) has 35 electrons and its electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5. Bromine wants to have a stable electron configuration by gaining 1 electron to complete its outermost shell, giving it a total of 8 electrons.
In the reaction, one calcium atom combines with two bromine atoms to form calcium bromide (CaBr2). Calcium loses its 2 electrons, becoming Ca2+ ion, and each bromine atom gains 1 electron, becoming Br^- ions. This results in the formation of an ionic bond between the cation (Ca2+) and anion (Br^-), thus achieving a stable electron configuration for both the calcium cation and the bromide anions.
This principle of achieving stable electron configurations is commonly observed in synthesis reactions where the elements involved have an opportunity to gain, lose, or share electrons in order to achieve a more stable configuration.