Types of CompoundsOverview~This booklet will explain what the types of compounds are, what they do, how to name them, and how to combine them. Ionic Compounds: To make an ionic compound, two or more elements are attracted to each other with opposing charges. The attracted elements must equal a charge of zero. They must have one metal cation and one nonmetal anion.
Molecular(Covalent): Molecular Compounds are held together by covalent bonds, their atoms share valence electrons to fill both of their shells. Thay are also inorganic and form discrete molecules. Molecular compounds are usually formed between two nonmetals. Acid: Acids are covalent compounds that dissolve completely in water and give off hydrogen ions. Simple Organic: A compound with at least one atom of carbon– though some carbon containing compounds are not considered organic such as carbides, carbonates, and cyanides– covalently linked to atoms of other elements. There are thousands of these types.
Ionic CompoundsBalancing ChargesIn order for a ionic compound to be formed, the charge of the elements must equal zero. To write their molecular formulas, you need to know how to balance the charges. For a simple example, take NaCl (sodium chloride).
Na has a 1+ charge and Cl has a 1- charge, thus together they equal zero. For a more complex compound, such as CaBr2 (calcium bromide), Ca has a 2+ charge and Br has a 1- charge. Together they equal a 1+ charge. To get to zero, simply take 2 Br atoms, making Br2 and giving it the charge of 2-.
Now 2+ and 2- balance out to equal zero. For polyatomic ions, it is the same, just a little more confusing. Just ignore the subscript on the polyatomic ion and balance the superscripts, putting the polyatomic ion and given subscript in parenthesis. For example, Mg2+ bonds to NO31- to form Magnesium nitrate Mg(NO3)2.
Binary Ionic CompoundsTo name a binary ionic compounds, first take into account the name of the element. For cations, which are positively charged ions, you just take the name of the element. For example, Na+ is just sodium. For anions, which are negatively charged ions, you take the element name and add the suffix -ide to the end. For example, Cl- is chloride. To make a compound, you put the cation first and then the anion with -ide on the end. So the compound NaCl, which is table salt, would be sodium chloride.
Ionic Compounds with Transition MetalsTo name ionic compounds with transition metals, you follow the same rules as binary ionic compounds– first the cation and then the anion with -ide added to the end– with one new rule. It is that because transition metals form multiple ions, you have to use Roman numerals to show which ion it is. For example, the transition metal copper has a Cu+ along with Cu2+ ion, so to name them, you have to write copper (I) for Cu+ and copper (II) for Cu2+.
So CuO would be copper (II) oxide and CuBr would be copper (I) bromide. This rule is for many transition metals, but not all.Ternary Ionic CompoundsThese contain a metal cation and a polyatomic anion.
A polyatomic ion is when there are two or more atoms bonded together that act as one. To name these ionic compounds, the cation is still first and stays the same as before. The polyatomic anion, however, is put in parentheses– only if a subscript is added– and the subscript is put outside of them. You also do not put the suffix -ide on the end, you keep the given name.
(See page 11 for common ions.) For example, Ca(NO3)4 is calcium nitrate, and is made up of Ca2+ and NO3- (see Balancing Charges). If a ternary compound has a transition metal with multiple ions, then still include the Roman numbers after the cation.Stock System & Classical SystemThe Stock System is used in ionic compounds with transition metals (though not all) to distinguish between the ions of one element. So, for example, Cr2+ is chromium(II) and Cr3+ is chromium(III).
If you were given the name chromium(III) oxide, you could see that it is Cr3+ for the formula because of the Roman numerals. From oxide, it is still just O. Since oxygen is 2+ and chromium is 3+, set it equal to zero (see Balancing Charges) and there’s your equation: Cr2O3. Occasionally, you will see the classical system for naming ions.
For this system you would take the element and add -ous for 2, and -ic for 3. So Cr2+ would be chromous and Cr3+ would be chrombic. Molecular CompoundA molecular compound is connection between atoms that results in the sharing of electrons between atoms, unlike transferring electrons similarly to Ionic Compounds. This sharing occurs between elements that are close to each other, usually being nonmetals with the occasional exception of a pair between nonmetal and metal. Molecular compounds are important because the element carbon does not form ionic bonds since it would have to either lose or gain 4 valence electrons. Through molecular bonding, carbon can share valence electrons through single, double, and triple bonds.
SingleSharing 1 pair of valence electronsLow reactivityC-CHigh bond strengthEx: methane, butane, ethane, propaneDoubleSharing 2 pairs of valence electronsModerate reactivityC=CModerate bond strengthEx: ethylene, propene, carbonyl compounds, azo compounds, imines, sulfoxidesTripleSharing 3 pairs of valence electronsHigh reactivityC?CLow bond strengthEx: nitrogen gas, cyanide ion, acetylene, carbon monoxideNamingThe element that is farthest left of the periodic table will come first. When the elements are in the same group, the element closer to the bottom will come first.When expressing how many atoms of an element in a molecule, you use greek prefixes in the names. The one exception not using mono- in the first name when there is only one atom of that element in the molecule.The second name of the compound will always end with -ideSome names will leave out the letter a or o to avoid complicated pronunciations. A compound such as N2O4 will be called dinitrogen tetroxide instead of tetraoxide.
Some elements will go by a name common names given to them instead of the name including greek prefixes such as H2O going by water instead of dihydrogen monoxide.ExamplesPCl3 = phosphorus trichlorideH2O = dihydrogen monoxide, waterCH4 = carbon tetrahydride, methaneSi3Br8 = trisilicon octabromideN3Cl7 = trinitrogen heptachlorideAcidsThese compounds are anions bonded with hydrogen to produce a compound that dissolves in water, creating an acid. When naming these compounds, you will add the prefix hydro- and change the -ide suffix to -ic. When a polyatomic anion includes oxygen, the suffix -ate and -ite will change to -ic and -ous in the respective order.
As an example the molecular compound HF, hydrogen fluoride will dissolve in water to form hydrofluoric acid.Example: Anion FormulaAnion NameAnion Formula including HAcid nameCl-chlorideHClHydrochloric acidF-fluorideHFHydrofluoric acidS2-sulfideH2SHydrosulfuric acidCO32-carbonateH2CO3Carbonic acidClO4-perchlorate HClO4Perchloric acidMnO4-permanganateHMnO4Permanganic acidNO2-nitriteHNO2Nitrous acidSO32-sulfiteH2SO3Sulfurous acidClO-hypochloriteHClOHypochlorous acidSimple OrganicAlkanes, Alkenes, & AlkynesThese are hydrocarbons, meaning they include only hydrogen and carbon. Alkanes are very simple, they are only single bonds between carbons. To name these, you count the number of carbons in the chain, which gives you the prefix according to this:The suffix for alkanes is just -ane. So for there are 3 carbons, so prop- and the suffix -ane.
So this is propane. To write the formula, you use the equation CnH2n+2, where n is the number of carbons. So for propane again, C3H8 is the formula if you were given only the name. With the diagram, you just count each carbon and hydrogen. For alkenes, they have double bonds between carbons. They are more complicated than alkanes. If there are 2 or 3 carbons, it is the same as above except the suffix is now -ene. If there are more than that, you must number the carbons so that the double bond has the lowest number, then at that to the beginning.
If we see C-C=C-C, then the double bond is on the second carbon. So this is 2-butene. Alkynes are the same as alkene, except they are triple-bonded. So they have the prefix -yne. So C-C?C-C-C would be 2-pentyne.Straight chain alcoholsThese are hydroxyls, meaning they end with -OH. For these, you count each carbon and the hydrogens with OH at the end.
For this:It would be C3H7OH. To name this, use the same prefix chart as above, counting the number of carbons, and add the suffix -anol. This is propanol.Aromatic Rings: BenzeneThese are rings of Benzene that can have other elements attached to them. If there is a benzene ring with Chlorine attached, it is simply chlorobenzene.