This gives a zero total charge for the formula. The resulting formula is MgO. Example 6: Write the name of the following formula: aluminum oxide.
Answer - This is the only possible way to get the positive and negative charges equal and keep the numbers to a minimum. Also, keep in mind that you cannot change the charges to make a formula correct. The resulting formula is Al 2 O 3. Warning: beware of the temptation to write the above formula as Al 3 O 2.
Write the correct formula for:. Binary Compounds of Cations with Variable Charges. The Stock System. There can be one of each element such as in CuCl or FeO. There can also be several of each element such as Fe 2 O 3 or SnBr 4. This lesson shows you how to name binary compounds from the formula when a cation of variable charge is involved.
The four formulas above are all examples of this type. The anions involved have only one charge. The type of naming you will learn about is called the Stock system or Stock's system. It was designed by Alfred Stock , a German chemist and first published in In his own words, he considered the system to be "simple, clear, immediately intelligible, capable of the most general application.
In , a German commission recommended Stock's system be adopted with some changes. For example, FeCl 2 ,which would have been named iron 2 -chloride according to Stock's original idea, became iron II chloride in the revised proposal. In , Stock approved of the Roman numerals, but felt it better to keep the hyphen and drop the parenthesis. This suggestion has not been followed, but the Stock system remains in use world-wide. Example 1: Write the name for: FeCl 2. Step 1 - the first part of the name is the unchanged name of the first element in the formula.
In this example, it would be iron. Here is how to determine its value :. Ignore the fact that it is negative. In this example it is one times two equals two.
This is the value of the Roman numeral to use. In this example, it is two divided by one equals two. The value of the Roman number equals the positive charge on the cation in this formula. Since the result of step 2 is 2, we then use iron II for the name. Notice that there is no space between the name and the parenthesis. Step 3 - the anion is named in the usual manner of stem plus " ide.
The correct name of the example is iron II chloride. Example 2: name this compound: CuCl 2. In this example, I've explained it differently. Compare it to the one above. Example 4 is also explained this way. This compound is named copper II chloride. Example 3: Write the name for: Fe 2 O 3. In this example, it is two times three equals six. In this example, it is six divided by two equals three. Note: this value of the Roman number equals the positive charge on the cation. In this example, the result of step 2 is 3.
That means that iron III will be used for the name. The correct name of the example is iron III oxide. Example 4: name this compound : SnO. This compound is named tin II oxide. Answer using the Stock system.
There are reasons for this behavior , but that is beyond the scope of this work. Example 1: mercury I chloride. The formula for this compound is Hg 2 Cl 2. It is not HgCl. You will be marked wrong on a test for doing so. Example 2: mercury I nitrate. The formula for this compound is Hg 2 NO 3 2. Once again, it is not reduced. In nature, mercury I comes in a set of two atoms, NOT just one. Example 3: hydrogen peroxide. The formula is H 2 O 2 and it is not reduced to HO. Same reason as above, peroxide travels as a group of two oxygen atoms, not one.
Example 4: sodium peroxide. The formula is Na 2 O 2. Given Name, Write the Formula. Example 1 - Write the formula for: copper II chloride. Step 1 - the first word tells you the symbol of the cation. In this case it is Cu. In this case it is a positive two. Step 3 - the anion symbol and charge comes from the second name. Step 4 - remembering the rule that a formula must have zero total charge, you write the formula CuCl 2. Example 2 - Write the formula for: copper I oxide.
It is Cu. It is a positive one. Step 4 - since a formula must have zero total charge, you write the formula Cu 2 O. Example 3 - Write the formula for: iron III sulfide.
Step 1 - the symbol of the cation is Fe. Step 2 - the charge on the cation is a positive three. Step 4 - since a formula must have zero total charge, you write the formula Fe 2 S 3.
Example 4 - Write the formula for: tin IV phosphide. First symbol is Sn from the name tin. This compound's formula is Sn 3 P 4. This graphic summarizes example Common Name System. There can also be several of each element such as Fe 2 O 3 or CuBr 2. This lesson shows you how to name binary compounds using the common naming system from the formula when a cation of variable charge is involved.
Important point to remember: the cations involved in this lesson have variable charges. He is known as the "Father of Modern Chemistry. Two typical names of chemicals up to this point in history are "foliated earth of tartar" and " phlogisticated vitriolic acid. Lavoisier's solution, which will be studied in this lesson, was to use different suffixes to indicate differences in composition. Specifically, the use of "- ous " and "- ic " will be studied.
Here is what the IUPAC currently says about this naming system: "The following systems are in use but not recommended: The system of indicating valence by means of the suffixes - ous and - ic added to the root of the name of the cation may be retained for elements exhibiting not more than two valences.
Example 1: FeO. Step 1 - the first part of the name is the root of the first element in the formula plus a suffix. For iron the root to use is " ferr -". The suffix will be either "- ous " or "- ic. Here is how to determine the suffix. This gives the positive charge on the cation.
The result from 1 and 2 just above is two. As you memorize the various charges, you will also internalize the above three steps. That last part merits a repeat: the lower of the two values will use the "- ous " ending and the higher will use "- ic. As you begin to learn these values, the question of lower and higher becomes much easier. Trust me! Step 2 - the anion is named in the usual manner of stem plus " ide.
The answer to this example is ferrous oxide. Example 2: Fe 2 O 3. When you multiply the anion's charge negative two by its subscript three and drop the sign, you get six for an answer. Then you divide the six by two the iron's subscript and you get three. This means the charge on each iron is positive three. Since this is the higher of the two charges, the term "ferric" is used. The answer to this example is ferric oxide.
Example 3: CuCl 2. The first part of the name comes from the first element's root: cupr -. This compound is named cupric chloride. Example 4: SnO. The first part of the name comes from the first element's root: stann -. This compound is named stannous oxide. Answers :. Example 1: cuprous chloride. Step 1 - cuprous is the name of a very specific cation. If you give your studies enough time, you will memorize all the names and charges, just like you have memorized many other things in your life.
Step 2 - chloride is the name of a specific anion. Step 3 - remembering thatthe total charge of the formula must be zero, you write the formula CuCl. Example 2: ferrous oxide. Following the usual rules, you write FeO for the formula. Example 3: ferric sulfide. The formula is Fe 2 S 3. Example 4: stannic phosphide. Just like "apple" or "light bulb" mean specific things.
Example 5: mercurous chloride. This formula is not reduced. Binary Compounds of Two Nonmetals. The Greek System. There can be one of each element such as in CO or NO.
This lesson shows you how to name binary compounds from the formula when two nonmetals are involved. Important point to remember: NO metals which act as the cation are involved.
That means one of the nonmetals will be acting in the positive role while the other is negative. In fact, you do not even need to know the charges, since the formula comes right from the element names and their prefixes. Be aware that heavy use of Greek number prefixes are used in this lesson.
Here are the first ten:. Example 1 - write the name for N 2 O. Example 2 - write the name for NO 2. Step 1 - part of the first name is the unchanged name of the first element in the formula. In the examples above, it would be nitrogen. If the subscript of the first element is 2 or more, you add a prefix to the name. In the first example above, you would write dinitrogen. You simply write the name, in this example it would be nitrogen. In the first example, the prefix is "mono-" since there is one oxygen.
In the second example, use " di -" because of two oxygens. The correct names of the two examples are dinitrogen monoxide and nitrogen dioxide. Note that "monoxide" is written rather than " monooxide. Example 3 - write the name for IF 7. Step 1 - the first element is iodine and there is only one.
This part of the name will be "iodine", NOT " monoiodine. Step 2 - the second element is fluorine, so "fluoride" is used.
Since there are seven, the prefix " hepta " is used. The name of this compound is iodine heptafluoride. Example 4 - write the name for N 2 O 5. Step 1 - the first element is nitrogen and there are two. This part of the name will be " dinitrogen. Step 2 - the second element is oxygen, so "oxide" is used. Since there are five, the prefix " penta " is used. The name of this compound is " dinitrogen pentaoxide.
Example 5 - write the name for XeF 2. The first part of the name comes from the first element's name: xenon. Since there is only one atom present, no prefix is used. This compound is named xenon difluoride. Example 6 - write the name for N 2 O 4. The first part of the name comes from the first element's name: nitrogen.
Since there are two atoms, the prefix " di -" is used giving dinitrogen. This compound is named dinitrogen tetroxide. Notice the dropping of the "a" in tetra. Just a reminder: this system of naming does not really have an offically accepted name, but is often called the Greek system or method. It involves use of Greek prefixes when naming binary compounds of two nonmetals. Sometimes you will see the Stock system applied to these types of compounds. Here is what the IUPAC currently says about that practice: "The Stock notation can be applied to both cations and anions, but preferably should not be applied to compounds between nonmetals.
Compounds Involving a Polyatomic Ion. They contain three or more elements, as opposed to only two in a binary compound. That naming technique is used only for binary compounds of two nonmetals. That means, if you see a formula like BaSO 4 , the name is not barium monosulfur tetraoxide. Many unaware ChemTeam students over the years have made this error and suffered for it. Consequently, a warning: it is important that you learn to recognize the presence of a polyatomic ion in a formula.
Many ChemTeam students have made it their first priority to make a set of flashcards with the name on one side and the ion and its charge on the other.
Then, carry them everywhere and use them. The cations used will be a mix of fixed charges AND variable charges. You must know which are which. Another warning: you must also know the charges associated with each polyatomic ion. Once again, many unaware ChemTeam students have thought this means nitrate has a minus three charge. Use of Parenthesis. When more than one polyatomic ion is required, parenthesis are used to enclose the ion with the subscript going outside the parenthesis.
For example, the very first formula used is Fe NO 3 2. Without the parenthesis, the formula would be FeNO 32 , a far cry from the correct formula. When you say a formula involving parenthesis out loud, you use the word "taken" as in the formula for ammonium sulfide , which is NH 4 2 S.
Out loud, you say "N H four taken twice S. You say " Cu Cl O three taken twice. Example 1 - write the name for Fe NO 3 2. Step 1 - decide if the cation is one showing variable charge. If so, a Roman numeral will be needed. In this case, iron does show variable charge. If a variable charge cation is involved, you must determine the Roman numeral involved. You do this by computing the total charge contributed by the polyatomic ion. Therefore, the iron must be a positive two, in order to keep the total charge of the formula at zero.
Step 2 - determine the name of the polyatomic ion. The correct name is iron II nitrate. The common name would be ferrous nitrate. Example 2 - write the name for NaOH. If there are more protons, the charge is positive. Monatomic anions are named by taking the root of the element name and applying an -ide ending.
Other important simple anions. Monatomic anions do not occur with multiple charges, thus each nonmetal can form only one monatomic anion, unlike some of the metals which can have multiple monatomic cations.
We can now make a more general statement about the formation of monatomic ions. Certain monatomic ions form when atoms gain or lose electrons to achieve a stable electron configuration for their highest energy electrons.
Metallic atoms lose one, two, or, at most, three electrons in order to form ions. The name of a monatomic cation is the same as the name of the neutral element.
Monatomic Ions. Ions are formed by the addition of electrons to, or the removal of electrons from, neutral atoms or molecules or other ions; by combination of ions with other particles; or by rupture of a covalent bond between two atoms in such a way that both of the electrons of the bond are left in association with one of the …. An ion is a charged atom or molecule. It is charged because the number of electrons do not equal the number of protons in the atom or molecule.
An atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom. Ions of like charge repel each other, and ions of opposite charge attract each other. Therefore, ions do not usually exist on their own, but will bind with ions of opposite charge to form a crystal lattice.
The resulting compound is called an ionic compound, and is said to be held together by ionic bonding. Because the bare nucleus can readily combine with other particles electrons, atoms, and molecules , the isolated hydrogen ion can exist only in a nearly particle-free space high vacuum and in the gaseous state.
You drink tiny amounts of it in every drop of water you drink. About one in every million molecules of water will have accepted a proton from another water molecule, forming a hydronium ion and at the same time a hydroxide ion. Pure hydronium ions will not exist on their own as a liquid that you could drink. The overall concentration of hydrogen ions is inversely related to its pH and can be measured on the pH scale Figure 1.
Therefore, the more hydrogen ions present, the lower the pH; conversely, the fewer hydrogen ions, the higher the pH. It is neither acidic nor basic, and has a pH of 7. One far end is not more than 1M of hydrogen ions, which results in a pH value of not more than 0.
While on the other end is not more than 1M of hydroxide ions which results in a pH value of not more than The pH value goes out of the range when the concentration of the solution exceeds 1M. Mostly — measured pH values will lie in the range 0 to 14, though negative pH values and values above 14 are entirely possible.
Since pH is a logarithmic scale, a difference of one pH unit is equivalent to a tenfold difference in hydrogen ion concentration. The pH of pure water H20 is 7 at 25oC, but when exposed to the carbon dioxide in the atmosphere this equilibrium results in a pH of approximately 5.
Answer: The correct answer is Acids measure below 7. The value on pH scales lies from 0 to 14 where 7 indicates a neutral pH that corresponding to neutral solutions like water.
Anything below 7. The range goes from 0 — 14, with 7 being neutral. To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter molarity. Example: What is the pOH of a solution that has a hydroxide ion concentration of 4. The pH scale, ranges from 0 strongly acidic to 14 strongly basic or alkaline.
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