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What are the Rules of Naming a Compound in Chemistry?


How are Chemical Compounds Named?

Chemical nomenclature is the process of naming compounds. Naming compounds is important to allow scientists to identify and recognize the different compounds. When naming molecular compounds prefixes are used to dictate the number of a given element present in the compound. For example:

  • “mono-” indicates one,
  • “di-” indicates two,
  • “tri-” is three,
  • “tetra-” is four,
  • “penta-” is five,
  •  “hexa-” is six,
  • “hepta-” is seven,
  • “octo-” is eight,
  • “nona-” is nine,
  • and “deca” is ten.

For a more in depth explanation check out this video.

How do you know whether to use 'ide' or 'ate', when naming a compound?

-ide is used for non-metal compounds generally. For example, Chlorine forms a chloride ion, so NaCl is Sodium Chloride. -ate and -ite are commonly used for polyatomic ions of Oxygen. -ate is used for the ion that has the largest number of Oxygen atoms. The -ite would be used for the ion with the smaller. NO2 and NO3 are known as Nitrite and Nitrate respectively. Nitrite has a smaller number of oxygen atoms so when added to an element it will be _ Nitrite. On the other than, Nitrate has a larger number of Oxygen atoms so when added to an element it is _ Nitrate Share your tips and advice for learning the names of chemical compounds in the comments.  

How do you name compounds in chemistry?

The elements that are joined together through chemical bonds are known as chemical compounds. The chemical bonds between the compounds are strong enough to make them act like a single substance. Do you know how many compounds are there? The answer is that there are more than 350,000 chemical compounds that are registered for use and production. You can easily search the list of compounds online. The properties of compounds are different than those of the elements that were used to make those compounds. Now, the question arises how these compounds are named in chemistry? The answer is simple. There is a standard method of naming chemical compounds that is employed by all the scientists  worldwide.

Rules for Naming Ionic or Molecular Compounds

Here are the simple steps to name compounds in chemistry: Step 1: Determine whether the compound in an ionic or molecular compound The first step is to identify whether the compound you are going to name is an ionic compound or a molecular compound. To do so, you should know what ionic and molecular compounds are.

  • The compound is ionic if it contains a metal. Metals are present on the middle and left side of the periodic table.
  • The compound is molecular if it contains two nonmetals. Nonmetals are present on the right side of the periodic table above the staircase, including hydrogen)

  Step 2: To the end of the second compound's name, add the word "ide"   After you have determined a molecular or ionic compound, the next step if to look at the second compound and replace the last three words with "ide". This rule is same for molecular or ionic compounds. For instance, if the second compound is chlorine, then you should remove "ine" and replace it with "ide", so that we can spell it "chloride".   Step 3: Check if you require roman numerals   Look for an ionic compound that has a transition metal that becomes a multivalent ion. If you have ionic compounds with transition metals, then you should add a roman numeral after the metal name to show the transition metal's charge. For instance, FeCl is named as iron (I) chloride and FeCl_2 is named as iron (II) chloride.   Step 4: Check if any prefixes are required Because there are no ionic charges to balance out molecular compounds, therefore you should use prefixes shown in the table below:

mono1
di2
tri3
tera4
penta5
hexa6
hepta7
octa8
nona9
deca10
For instance, CO_2 is named as carbon dioxide and CO is named as carbon mono oxide.  

Naming Ionic Compounds that Contain Polyatomic Ions

The rules for naming ionic compounds containing polyatomic ions are different. Polyatomic ions contain more than one atom. For instance, SO^{-}_{4} has one nitrogen atom and four oxygen atoms. In a polyatomic ion, the atoms are generally covalently bonded to each other. They act as a single charged unit. Most of the compounds containing polyatomic ions end with "ate" or "ite". Only some of them end with "ide". For instance, Na_2SO_4 is named as sodium sulphate and Na_2SO_4 is called sodium sulphite.  

Naming Acids

The prefix  "hydro" and the suffix name"ic" are used to name hydro acids. For instance, HF is called hydrofluoric acid and HCl is named as hydrochloric acid. Oxoacids are acids that contain oxygen. We use the suffix "ic" or "ous" while naming them. The suffix "ic" is used when the acid has more oxygen atoms. For instance, H_2SO_4 is named sulphuric acid.  

What are the three types of compounds?

We all know that a chemical element has one type of atom only. When a substance contains more than one kind of atom, then we say that it is a compound. In other words, we can say that a compound refers to a substance in which two or more atoms are bonded with each other.

Millions of compounds exist and all fall in the following three broad categories:

1) Ionic Compounds These compounds are made up of ions. Ions are charged particles that are made when an atom gains or loses  electrons. There are two types of ions: cation and anion. A cation is a positively charged ion and the anion is a negatively charged ion. These compounds are generally formed by a reaction between a metal and a nonmetal. To determine how to name these compounds, see the rules for naming ionic compounds in the previous section. 2) Molecular or Covalent Compounds They are formed when elements of the compound share electrons in a covalent bond to make up a molecule. These compounds are formed by the reaction between two nonmetals. 3) Acids Acids are compounds that contain hydrogen. It is easy to recognize acids as they contain hydrogen and anion. For instance, HNO_3 is named as nitric acid and H_2SO_4 is named as sulphuric acid.  

How do you identify types of compounds?

You can identify the type of compound by simply looking at the nature of its composition. Ionic Compounds: These compounds are formed when metal and non-metal are joined together. If you see that a compound is made from a metal and nonmetal, then you can easily categorize it as an ionic compound. For instance, NaCl is an ionic compound because sodium is a metal and chlorine is a nonmetal.   Covalent compounds: These compounds are formed when two nonmetals are held together by a covalent bond. When you see a compound with two or more nonmetals, then you can easily term it as a covalent compound.  For instance, carbon monoxide is made from two nonmetals carbon and oxygen, hence it is a covalent compound   Acids: Acids contain hydrogen and anion.  

What are the general rules for nomenclature? What are nomenclature rules?

Scientists employ nomenclature to name compounds clearly in chemistry. Ionic and molecular compounds are named using distinct methods. Nomenclature in chemistry refers to a set of rules to generate systematic names of  compounds. The nomenclature which is used by the chemists and scientists worldwide is created and developed by the IUPAC (International Union of Pure and Applied Chemistry).

Rules for Nomenclature

A) Binary ionic compounds are made up of metal and non-metal. While naming the compound, the name of the metal is written first, followed by the name of the non-metal. The last three alphabets of the non-metal are replaced with "ide". B) If the compound contains polyatomic ion, then the last three alphabets of a non-metal are replaced with "ate" or "ite". "ate" is employed when there are more oxygen atoms present in a compound and "ite" is used when number of oxygen atoms present in a compound is less. Some compounds also contain "ide" for instance OH (hydroxide). C) To name binary compounds between two nonmetals, prefixes such as 1 = mono, 2 - di, 3 = tri, and so on are used. For instance, CO_2 is named as carbon dioxide and CO is named as carbon monoxide.  

Why is nomenclature important? What is the purpose of nomenclature?

There are two objectives of using nomenclature in chemistry:

  • To make sure that a spoken or written chemical name does not contain any ambiguity regarding the chemical compound the name is referring towards. It is important that each chemical name points towards a single substance.
  • To ascertain that each substance has one name only (although alternative names are acceptable in some cases)
  • To help the chemists communicate with their peers easily.
Answers
Hi,
mjhansford
31 May 2013
-ide is used for non-metal compounds generally. For example, Chlorine forms a chloride ion, so NaCl is Sodium Chloride. -ate and -ite are commonly used for polyatomic ions of Oxygen. -ate is used for the ion that has the largest number of Oxygen atoms. the -ite would be used for the ion with the smaller. NO2 and NO3 are known as Nitrite and Nitrate respectively. Nitrite has a smaller number of oxygen atoms so when added to an element it will be _ Nitrite. On the other than, Nitrate has a larger number of Oxygen atoms so when added to an element it is _ Nitrate.Hope that helps!
mjhansford
31 May 2013
thank you! this helped loads
ellsbells7
26 June 2013
how are you meant to know whether it's the maximum or fewer (ate or ite) for a polyatomic ion? just memorize...?
ree
23 October 2020
Thanks for your suggestion
Abhishek Kumar
26 October 2020
@ree yes the only thing you can do to remember polyatomic atoms is to memorize them
Cat
13 November 2020
That helped thanks
Dai
27 December 2020
When I took chemistry in high school the instructor said that the ate and ite suffixes depended on the charge of the cation, that is, ate has a higher positive charge than ite. Of course, this does correlate exactly with your definition. Just a bit of slightly interesting info.
Carlos
29 January 2021
This helped a lot. But it didn't answer my question. My question: What do you name a compound when it contains Metal, Hydrogen, and Oxygen. Please let me know.
Michelle Bones
31 January 2022
Yalu, Dio!!
Kujo Jotaro
05 March 2022
Hello, I am not sure if you will see this Michelle Bones however I will explain your question for you anyway. But first I will clear a few confusions of original answer, I will not touch all since they seem irrelevant to what your original question is. To start I want to say that though acids are a special type of compound, why they were listed separate from ionic compounds eludes me. Leaving organic acids out of this I will explain about acids containing an acidic hydrogen, they simple are just ionic compounds containing a highly oxidized (not fully oxidized) metal oxides or metalloid oxides or in the case of halogens just hydrogen. Because the metalloid is so oxidized it draw a lot of electron density so the hydrogen ions cannot form a strong bond with the oxygen like it normally would. This allows dissolution of the ions in aqueous solutions. What causes a pH drop which is an increase in acidity is actually just H+ or some might say the hydronium ion H3O+ that forms from the dissolution of the acids. There are a few definitions of acids aside from the acidic hydrogen example I gave, but they are not necessary for this explanation. -ide how to use it. The original answer said the -ide is generally used for non-metallic compounds then goes on to describe a metallic compounds. Sodium Chloride is a metallic compound as Sodium is a metal. -ide is used to describe non-metallic ion, chloride, sulfide, nitride, phosphide. Also generally infers that most compounds ending in -ide are non-metallic. This is incorrect, in fact in order non-metals or non-metalloid to form an ionic compounds one of them needs to be strongly oxidized. Take chloride dioxide also known as the chlorite ion as an example. ClO2-, how the heck can that work, Chloride ion Cl- is -1, the oxide ion O-2is -2, like charges don't attract how the heck do you join 2 negative compounds. It takes a lot of work and needs to be bonded to a cation like sodium chlorite, and it will decompose over time as itself is a strong. It is such a strong oxidizer and so unstable most chlorite compounds dangerously decompose at a slight bump. -ide is also used to refer to a non-metallic compound which includes metalloids are directly bonded directly a metal, or a non-metal non-metalloid bonded to a metalloid, or 2 metalloids bonded. I will give some examples your copper as we all know copper is clearly a metal. Copper Sulfide Cu2S Copper Nitride Cu3N Copper (II) Chloride CuCl2 Copper (I) Chloride CuCl Using the metalloid sulfur and non-metals Sulfur Nitride which comes in many forms S5N6, S4N4, S4N2 and so on. Phosphorus Sulfide which follows the formula P4Sx where x is less than 10. P4S4, P4S5, P4S7 and so on, Now between the metelloid sulfer and a non metal chlorine, -Sulfur Dichloride SCl2 -Disulfur Dichloride S2Cl2 -Sulfur Tetrachloride SCl4 They did explain -ate and -ite a little weird but the original question doesn't seem to be about polyatomic ions but about how to name a compound containing metallic hydrogen, so I will leave the polyatomic stuff alone and get to the point. Hydrogen is a unique atom in that the H+ ion is literally just a proton nothing more nothing less. Hydrogen in general has no neutrons , 1 proton the valence shell can hold 2 electrons. Hydrogen has 2 ionic forms H+ and H- and also forms a covalent bond with other cations including another hydrogen. As suggested hydrogen can take on more than 1 form, in nature hydrogen is a highly flammable gas H2 but under certain conditions can turn into a metal. These conditions are extreme and hard to achieve. Now onto naming. As mentioned hydrogen is a unique atom. But the naming conventions follow the same conventions as naming other metallic metalloid compounds that are bonded to non-polyatomic ions. The name of the metallic or metalloid cation by its full name followed by the metalloid or non-metal with the -ide suffix. When metallic hydrogen is bonded to oxygen it forms the compound H2O which has 2 official names oxidane and water. I bet you are thinking, "Hey man you said they follow the same convention as other metallic and metalloid compounds, these 2 names don't make sense". If you are you would be absolutely right, but the suffix -ane along with -onium are for another lesson. Those are the 2 names accepted names, but like many compounds it has other names, just some not accepted by IUPAC or the general community. So here it goes, H2O can also be called Hydrogen Oxide, or Dihydrogen Oxide, Hydrogen Monoxide, Dihydrogen Monoxide, just never use them in any reports, publications, papers, or generally don't use them at all. They are more or less used as a joke like this one. "I stopped the drinking tap water after I found out my cities water supply contained high amounts of Hydrogen Monoxide".
Ben
11 March 2022
-ide is used for non-metal compounds generally. For example, Chlorine forms a chloride ion, so NaCl is Sodium Chloride. -ate and -ite are commonly used for polyatomic ions of Oxygen. -ate is used for the ion that has the largest number of Oxygen atoms. the -ite would be used for the ion with the smaller. NO2 and NO3 are known as Nitrite and Nitrate respectively. Nitrite has a smaller number of oxygen atoms so when added to an element it will be _ Nitrite. On the other than, Nitrate has a larger number of Oxygen atoms so when added to an element it is _ Nitrate.Hope that helps!
14 March 2022
thanks!
Mohd Akram
16 March 2022
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