"IUPAC nomenclature: elements, monatomic ions and binary compounds"
The iron in a bridge and the carbon dioxide you breathe out are two substances with very different names, but those names are not chosen at random: they follow fixed rules, the same all over the world, so that any formula can be named without ambiguity.
Elements
Both iron nails and the gas inside an oxygen cylinder are made up of atoms of a single kind: how do we classify and name these materials, which cannot be broken down into other substances?
Elements made up of separate atoms are named in the same way as the element: iron, helium. If they form molecules, a prefix shows how many atoms each molecule has: $\text{O}_2$ is dioxygen (or, simply, oxygen) and $\text{O}_3$ is trioxygen (ozone).
The iron in a bridge ($\text{Fe}$) and the carbon dioxide we release when breathing ($\text{CO}2$): one of the two is a simple substance and the other is a compound. The…
The iron in a bridge ($\text{Fe}$) and the carbon dioxide we release when breathing ($\text{CO}_2$): one of the two is a simple substance and the other is a compound. The figure shows their particle models.
Which is which? Explain the difference between the two.
Oxygen ($\text{O}2$), nitrogen ($\text{N}2$), iron ($\text{Fe}$) and helium ($\text{He}$) are simple substances. Look at their formulas and state which of them form…
Oxygen ($\text{O}_2$), nitrogen ($\text{N}_2$), iron ($\text{Fe}$) and helium ($\text{He}$) are simple substances. Look at their formulas and state which of them form molecules, which are made up of individual atoms and whether any of them fits neither case.
Monatomic ions
An atom that gains or loses electrons becomes an ion, and that ion has its own name.
When a sodium atom loses an electron, it becomes $\text{Na}^+$. The figure shows the process. a) Explain what an ion is. b) Does $\text{Na}^+$ have a positive or a…
When a sodium atom loses an electron, it becomes $\text{Na}^+$. The figure shows the process.
- a) Explain what an ion is.
- b) Does $\text{Na}^+$ have a positive or a negative charge?
- c) What is this ion called?
Name these three monatomic ions: $\text{Cl}^-$, $\text{Ca}^{2+}$ and $\text{O}^{2-}$. Hint: positive ions keep the name of the atom (for example, the $\text{Na}^+$ ion…
Name these three monatomic ions: $\text{Cl}^-$, $\text{Ca}^{2+}$ and $\text{O}^{2-}$. Hint: positive ions keep the name of the atom (for example, the $\text{Na}^+$ ion is called sodium ion) and negative ions end in -ide (for example, the $\text{S}^{2-}$ ion is called sulfide ion).
In your bones, calcium is present as $\text{Ca}^{2+}$. a) What does that $2+$ mean? b) How many electrons has the calcium atom lost? c) What is this ion called?
In your bones, calcium is present as $\text{Ca}^{2+}$.
- a) What does that $2+$ mean?
- b) How many electrons has the calcium atom lost?
- c) What is this ion called?
Naming binary compounds with prefixes
A binary compound is made up of two elements. The simplest way to name it uses Greek prefixes that show how many atoms there are of each one.
Many fire extinguishers are filled with $\text{CO}2$ gas. Naming it with Greek prefixes (mono-, di-, tri-) according to the number of oxygen atoms it has, what is the…
Many fire extinguishers are filled with $\text{CO}_2$ gas. Naming it with Greek prefixes (mono-, di-, tri-) according to the number of oxygen atoms it has, what is the name of this gas?
Using the prefixes mono-, di- and tri-, write the formula for these two substances: carbon monoxide and carbon dioxide. What is the difference between the two molecules?
Using the prefixes mono-, di- and tri-, write the formula for these two substances: carbon monoxide and carbon dioxide. What is the difference between the two molecules?
Compounds of oxygen with another element are called oxides and are named "[element] oxide". Milk of magnesia from pharmacies contains $\text{MgO}$: name it. Also name…
Compounds of oxygen with another element are called oxides and are named "[element] oxide". Milk of magnesia from pharmacies contains $\text{MgO}$: name it. Also name the compound $\text{Na}_2\text{O}$.
Valencies and Stock nomenclature
Some metals, such as iron, can form more than one different ion ($\text{Fe}^{2+}$ or $\text{Fe}^{3+}$). In those cases we need to say which valency the metal is using in that compound.
The reddish oxide that appears on an old bicycle is $\text{Fe}2\text{O}3$, and in it iron has a valency of $3$. Name it in both ways: using the prefixes mono-, di-, tri-…
The reddish oxide that appears on an old bicycle is $\text{Fe}_2\text{O}_3$, and in it iron has a valency of $3$. Name it in both ways: using the prefixes mono-, di-, tri- and using the valency of iron written in brackets in Roman numerals.
Troilite, a mineral found in many meteorites, has the formula $\text{FeS}$, and in it iron has a valency of $2$. a) Name it using Stock nomenclature (the valency in…
Troilite, a mineral found in many meteorites, has the formula $\text{FeS}$, and in it iron has a valency of $2$.
- a) Name it using Stock nomenclature (the valency in brackets and in Roman numerals).
- b) Also name it using prefixes.
Iron can form two different ions: $\text{Fe}^{2+}$ and $\text{Fe}^{3+}$. a) Write the formula of iron(II) oxide, formed by $\text{Fe}^{2+}$ and $\text{O}^{2-}$. b) Write…
Iron can form two different ions: $\text{Fe}^{2+}$ and $\text{Fe}^{3+}$.
- a) Write the formula of iron(II) oxide, formed by $\text{Fe}^{2+}$ and $\text{O}^{2-}$.
- b) Write the formula of iron(III) oxide.
- c) Name both oxides using prefixes.
From formula to name and back
Common salt ($\text{NaCl}$) is made of positive and negative ions, but a salt cellar does not give you an electric shock when you touch it: how do those ions combine so that the final compound has no net charge?
To write the formula of a compound from its ions, the positive and negative charges must balance so that they add up to zero.
Fluorite, a colourful mineral, is $\text{CaF}2$. a) Name this compound (remember the ending -ide). b) Now in reverse: write the formula of sodium sulfide, which has two…
Fluorite, a colourful mineral, is $\text{CaF}_2$.
- a) Name this compound (remember the ending -ide).
- b) Now in reverse: write the formula of sodium sulfide, which has two sodium atoms for every sulfur atom.
Aluminium always forms the $\text{Al}^{3+}$ ion and oxygen forms the $\text{O}^{2-}$ ion. a) Work out how many ions of each type are needed for the total charge of…
Aluminium always forms the $\text{Al}^{3+}$ ion and oxygen forms the $\text{O}^{2-}$ ion.
- a) Work out how many ions of each type are needed for the total charge of aluminium oxide to be zero.
- b) Write the formula of aluminium oxide.
In nature, the salts $\text{NaCl}$ and $\text{CaCl}2$ exist, but a $\text{NaCl}2$ salt has never been found. Use the charges of the ions $\text{Na}^+$, $\text{Ca}^{2+}$…
In nature, the salts $\text{NaCl}$ and $\text{CaCl}_2$ exist, but a $\text{NaCl}_2$ salt has never been found. Use the charges of the ions $\text{Na}^+$, $\text{Ca}^{2+}$ and $\text{Cl}^-$ to justify why the formula $\text{NaCl}_2$ is impossible and the other two can exist.