"Naming elements, 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 tank 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 of separate atoms are named with the name of the element: iron, helium. If they form molecules, a prefix shows how many atoms are in each molecule: $\text{O}_2$ 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 ion is an atom that has gained or lost electrons, so it has an electric charge. If it loses electrons it has more protons than electrons and is positive; if it gains electrons it is negative. Each 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. When both elements are nonmetals, the compound is molecular and its name 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?
Naming ionic compounds (metal + nonmetal)
Table salt, $\text{NaCl}$, contains a metal and a nonmetal. Do we need prefixes to name it?
A compound of a metal with a nonmetal is made of ions. Name the metal first (it keeps its name), then the nonmetal with the ending -ide. You do not say the subscripts.
When a metal combines with a non-metal, the compound is named by placing the name of the metal first and then the name of the non-metal with the ending -ide. Apply the…
When a metal combines with a non-metal, the compound is named by placing the name of the metal first and then the name of the non-metal with the ending -ide. Apply the rule and name table salt, $\text{NaCl}$, as well as the compound $\text{CaS}$.
Compounds of oxygen with another element are called oxides and are named "[element] oxide". Milk of magnesia from drugstores 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 drugstores contains $\text{MgO}$: name it. Also name the compound $\text{Na}_2\text{O}$.
When hydrogen combines with a metal, the compound is called a hydride. Name these two compounds: $\text{NaH}$ and $\text{CaH}2$.
When hydrogen combines with a metal, the compound is called a hydride. Name these two compounds: $\text{NaH}$ and $\text{CaH}_2$.
Metals with more than one charge: Stock system
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 charge the metal has in that compound.
Classify each substance as an element, oxide, hydride, or binary salt, and write its name: a) $\text{O}2$ b) $\text{Na}2\text{O}$ c) $\text{CaH}2$ d) $\text{FeS}$ e)…
Classify each substance as an element, oxide, hydride, or binary salt, and write its name:
- a) $\text{O}_2$
- b) $\text{Na}_2\text{O}$
- c) $\text{CaH}_2$
- d) $\text{FeS}$
- e) $\text{N}_2$
- f) $\text{MgO}$
From formula to name and back
Common salt ($\text{NaCl}$) is made of positive and negative ions, but a salt shaker 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 colorful 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 colorful 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.
Common salt is made up of $\text{Na}^+$ ions and $\text{Cl}^-$ ions arranged in a lattice. The figure shows a section of that lattice. a) Explain why the same number of…
Common salt is made up of $\text{Na}^+$ ions and $\text{Cl}^-$ ions arranged in a lattice. The figure shows a section of that lattice.
- a) Explain why the same number of ions of each type is needed for the salt to be neutral.
- b) Write the formula of the salt and reason why it cannot be $\text{Na}_2\text{Cl}$.
Back to the start: the iron in a bridge ($\text{Fe}$) is an element named just "iron", and the carbon dioxide you breathe out ($\text{CO}_2$) is a molecular compound of two nonmetals, so its name uses a prefix.