naming of binary compounds

A binary compound is a compound that consists of a combination of two elements. Compounds that end in IDE indicate that they contain only two elements. The first element is usually a positively charged metal, and the second element is usually a negatively charged nonmetal. The positively charged ion is the name of the metal, while the negatively charged ion consists of the stem plus the suffix IDE.

These stems are placed in the second part of the binary compound's chemical name, before the ide. Here are some examples using the element stems and the suffix ide.

CaO is calcium oxide because you have a calcium atom bonded to an oxygen atom. Since this is a binary compound (meaning that it is a compound comprised of only two elements) there is a positive and a negative ion. The positive ion is calcium, because it is a metal,so the oxygen is the negative ion. Now we write calcium as the name of the metal, and ox as the prefix of the second word (because oxygen's stem is ox). Lastly, we attach the suffix ide behind the ox to get the name calcium oxide.

AlN is aluminum nitride because you have an aluminum atom bonded to a nitrogen atom. Since this is a binary compound there is a positive and a negative ion. The positive ion is aluminum, because it is a metal,so the nitrogen is the negative ion. Now we write aluminum as the name of the metal, and nitr as the prefix of the second word (because nitrogen's stem is nitr). Lastly, we attach the suffix ide behind the nitr to get the name aluminum nitride.

K₂S is potassium sulfide because you have a potssium atom bonded to a sulfur atom. Since this is a binary compound there is a positive and a negative ion. The positive ion is potassium, because it is a metal, so the sulfur is the negative ion. Now we write potassium as the name of the metal, and sulf as the prefix of the second word (because sulfur's stem is sulf). Lastly, we attach the suffix ide behind the sulf to get the name potassium sulfide.

NaCl is sodium chloride because you have a sodium atom bonded to a chlorine atom. Since this is a binary compound there is a positive and a negative ion. The positive ion is sodium, because it is a metal, so the chlorine is the negative ion. Now we write sodium as the name of the metal, and chlor as the prefix of the second word (because chlorine's stem is chlor). Lastly, we attach the suffix ide behind the chlor to get the name sodium chloride.

Remember that the positively charged ion is the name of the metal, while the negatively charged ion consists of its stem plus a suffix (so far we have only used IDE). So far we have seen that in the name of a chemical compound, the first element usually is positive, and is the first part of the name. The second element in the compound's name is usually negative.

We now find that the ammonium radical, NH₄⁺, is considered as a simple positive ion, and even though it is not a metal, it would go at the front of a compound name. Here are some examples:

NH₄Cl is ammonium chloride because you have an ammonium radical bonded to a chlorine atom. Since this is considered a binary compound there is a positive and a negative ion. The positive ion is ammonium even though it is not a metal. That makes the the chlorine the negative ion. Now we write ammonium as the name of the metal, and chlor as the prefix of the second word (because chlorine's stem is chlor). Lastly, we attach the suffix ide behind the chlor to get the compound's name, ammonium chloride.

(NH₄)₂S is ammonium sulfide because you have an ammonium radical bonded to a sulfur atom. Since this is a binary compound there is a positive and a negative ion. The positive ion is ammonium even though it is not a metal. That makes the sulfur the negative ion. Now we write ammonium as the name of the metal, and sulf as the prefix of the second word (because sulfur's stem is sulf). Lastly, we attach the suffix ide behind the sulf to get the compound's name, ammonium sulfide.

KCN is potassium cyanide because you have a potassium atom bonded to a cyanide atom. Since this is a binary compound, there is a positive and a negative ion. The positive ion is potassium because it has a positive charge. CN^-, the cyanide ion, is considered the negative ion. Now we write potassium as the name of the metal, and cyanide is the negative ion.
Mg(OH)₂ is magnesium hydroxide
NH₄CN is ammonium cyanide

Some metallic ions can have two valence states, the one with the lower valence has the ending OUS while the one with the higher valence has the ending IC. Under the new international system, the valence is designated by a Roman numeral.

NO₂ is nitrogen dioxide because you have a nitrogen atom bonded to two oxygen atoms. Since this is a binary compound of two nonmetals, we use the new way of naming we just learned. We keep nitrogen as the first name, and attach the prefix di before the oxygen because there are two atoms of oxygen. We then add the ox stem from oxygen after the di prefix. We attach the ide suffic after ox, and we have the finished product, nitrogen dioxide.