Naming Chemical Compounds Otherwise known as The Ball of Confusion

These rules apply to Inorganic Compounds – Organic Compounds that use Carbon, Hydrogen and Oxygen require a new set of rules! You need to know the oxidation numbers of the elements in the Roman Numeral Groups Forming compounds are really oxidation (losing e-) and reduction (gaining e-) reactions Remember: LEO – lose e- oxidation and GER – gain e- reduction

+3 +/-4 -3 -2 -1 0 +1 +2

Know These!

Confused Yet? Just wait. . . . Remember - a pure and stable element has an oxidation number of zero, meaning it is neutrally charged A single atom has an oxidation number equal to its charge. Some atoms have a common charge: F is always -1, even in compounds; Cl, Br and I are always -1 except when joined with O or F; H is usually +1; and O is usually -2.

Compounds or Molecules These are made of two or more atoms joined together through their valence electrons The joining are called bonds These can be ionic, covalent (polar or nonpolar) or metallic bonds Let’s move onto Ionic Bonds first. . . .

Ionic Bonds These are the bonds between a metal and a nonmetal The metal Ion is positively charged and called a cation The nonmetal Ion is negatively charged and called an anion The bonded molecule should be neutrally charged when finished

Knowing where the metals and nonmetals are on the table will make your life easier

Let’s take a moment to discuss polyatomic ions. . . This is a molecule that acts as a cation or anion For example: NH4+ ammonium N3- azide ClO4- perchlorate CN- cyanide HCO3- bicarbonate OH- hydroxide CrzO7-2 chromate NO3- nitrate ClO3- chlorate C2H3O2- acetate Don’t PANIC – I have a list to give to you!

This applies even is using a polyatomic ion In an Ionic Compound – balance the molecule using the criss-cross rule Mg +2 + Cl-1 Mg Cl2 The one is understood. This applies even is using a polyatomic ion

In an Ionic Bond – one or more electrons are lost or gained by the atoms involved This allows the atoms to have a complete valence shell – following the octet rule

(NH4)2O The parentheses are used to keep Pb+4 + CO3-2 the polyatomic together Pb+4 + CO3-2 Pb2 (CO3)4 and this can be simplified by reducing the subscripts to Pb(CO3)2

Naming Ionic Compounds is really simple: 1. Name the cation (metal) using its proper name; if it is a polyatomic, do the same 2. Then, using the stem of the anion (nonmetal), simply add the suffix “ide” Zinc + Chlorine = Zinc Chloride Iron + Oxygen = Iron Oxide Lithium + Cyanide = Lithium Cyanide Ammonium + Fluorine = Ammonium Fluoride Cobalt + Phosphorous = Cobalt Phosphide

Transition Metals present an issue for balancing and naming molecules since they can have varying oxidation states For example: Manganese can be a +2 or +3 Iron can be a +2 or +3 Lead can be a +2, or even a +4 Copper is a +1 or +2 Gold is usually a +1 or +3 And Hydrogen is a +1 or a -1!

If it is a Ternary Compound (more than two different elements), name the cation first, then the ending is either “ate” or “ite” These you just got to learn! For example – Be(HSO3)2 is Berylium Hydrogen Sulfite and Fe(OH)2 is Iron (II) Hydroxide

So, this means you look for clues in the charge of the anion if given the molecule If given the name of the metal, it may have a roman numeral in parentheses like this: iron (II) or lead (IV) and this indicates the charge Otherwise – look up the possible charges in the CRC or the list I handed out!

If given the name like iron (II) chloride – you know the formula for the molecule is Fe Cl2 . . . . Since Fe has a +2 charge and Cl has a -1, using the criss-cross rule, we get this formula unit! Confused yet?

Covalent Compounds These can be monatomic or polyatomic compounds It is a bond between two nonmetals They share a pair of electrons They can be subgrouped into polar or nonpolar If a binary compound (2 atoms) – use the same rules as in Ionic Compounds

If it has more than one atom – need to use the prefixes Number Prefix Number Prefix 1 Mono 7 Hepta 2 Di 8 Octa 3 Tri 9 Nona 4 Tetra 10 Deca 5 Penta 11 Undeca 6 Hexa 12 Dodeca

P4S10 becomes Tetraphosphorous Decasulfide For example: P4S10 becomes Tetraphosphorous Decasulfide P2O5 becomes Diphosphorous Pentaoxide SF6 becomes Sulfur Hexafluoride SiBr4 becomes Silicon Tetrabromide

Covalent Bonds can be Polar or Nonpolar A nonpolar has no discernable negative or positively charged sides A polar covalent bond means one Side is negative and the positive

Some elements are able to form more than one oxyanion (polyatomic ions that contain oxygen), each containing a different number of oxygen atoms. For example, chlorine can combine with oxygen in four ways to form four different oxyanions: ClO4-, ClO3-, ClO2-, and ClO- (Note that in a family of oxyanions, the charge remains the same; only the number of oxygen atoms varies.) The most common of the chlorine oxyanions is chlorate, ClO3-. In fact, you will generally find that the most common of an element’s oxyanions has a name with the form (root)ate.

The anion with one more oxygen atom than the (root)ate anion is named by putting per- at the beginning of the root and -ate at the end. For example, ClO4- is perchlorate. The anion with one fewer oxygen atom than the (root)ate anion is named with -ite on the end of the root. ClO2- is chlorite. The anion with two less oxygen atoms than the (root)ate anion is named by putting hypo- at the beginning of the root and -ite at the end. ClO- is hypochlorite.

Oxyanion Example ClO- Hypochlorite ClO2- Chlorite ClO3- Chlorate ClO4- Perchlorate  

Some compounds have common names as well as their scientific names – you should learn these and others! NO nitrogen monoxide nitric oxide H2O dihydrogen monoxide water NH3 nitrogen trihydride ammonia CH4 carbon tetrahydride methane C4H10 tetracarbon decahydride butane

The name is hydro + halogen name + suffix “ic” Finally – naming acids. An acid is mixed with hydrogen and usually contains a halogen The name is hydro + halogen name + suffix “ic” Including HCl - hydrochloric acid HF - hydrofluoric acid H2SO4 - sulfuric acid (a slight modification here)

To review:

it is the only way to learn it! Still confused – you need to ask questions, study what we’ve talked about, and try doing it – it is the only way to learn it!