Names of Ions vs Elements (Sec 3)

This is another area that seems to be causing confusion to at least half of the students. The good news is that it is only half the students who don't get it.

This is what I saw in the test.

CaCO3 - Calcium Carbonate :)

Elements present in the compound: Calcium, Carbonate :( !!!

Obviously, there are some misconceptions here. Carbonate is the name given for a group of elements which form the CO3^2- ion. However, the elements that made up that ion are carbon and oxygen.

(Note: I used ^ as a sign that it is superscript for the charge as there is none in this blog, but bear in mind ^ is not part of chemical formulas of ions)

Likewise, in naming compounds, we have the halogens (F, Cl, Br, I) which are named as fluorine, chlorine, bromine and iodine respectively.

However, when they are written as part of a compound, their -ine would change to -ide.

e.g. NaCl is named as sodium chloride and not as sodium chlorine, but the element that is present in that compound is chlorine and not chloride.

Shockingly, such a simple knowledge is lacking even in the sec 4s who wrote that I^- as iodine instead of iodide ion.

Conclusion?

Naming of coumpounds:

CaSO4 - calcium sulphate
CaCO3 - calcium carbonate
KNO3 - potassium nitrate
KOH - potassium hydroxide
NaF - sodium fluoride
NaCl - sodium chloride
NaBr - sodium bromide
NaI - sodium iodide

Elements present in compounds:

CaSO4 - calcium, sulphur, oxygen
CaCO3 - calcium, carbon, oxygen
KNO3 - potassium, nitrogen, oxygen
KOH - potassium, hydrogen, oxygen
NaF - sodium, fluorine
NaCl - sodium, chlorine
NaBr - sodium, bromine
NaI - sodium, iodine