Video Transcript
What would the name of a compound
of calcium and fluorine be?
To name a compound that contains
the elements calcium and fluorine, we must first determine what type of compound we
are dealing with by locating the two elements on the periodic table. Calcium’s chemical symbol is Ca and
can be found on the periodic table in group two, period four. Fluorine has the chemical symbol F
and can be found on the periodic table in group 17, period two. With calcium being a metal due to
it being to the left-hand side of the metalloid staircase, as it is sometimes known,
and fluorine being a nonmetal, which aside from the element hydrogen are generally
found to the right-hand side of the metalloid staircase, we know we must be dealing
with an ionic compound, which consists of positively charged cations and negatively
charged anions that are bound together through electrostatic attractions.
We know we have an ionic compound
because metals, like calcium, tend to lose electrons to form positively charged
cations and nonmetals, like fluorine, tend to gain electrons to form negatively
charged anions. Since calcium is a group two metal,
also known as the alkaline earth metals, it will form a two plus charge cation, as
do the other metals in group two when they become cations. Fluorine, a group 17 nonmetal, also
known as one of the halogens, will form a one minus anion, as do the other nonmetals
in group 17 when they become anions.
Ions of calcium and fluorine can be
combined to form a mononuclear ionic compound. It is classified as such because
the calcium metal ion and the fluorine nonmetal ion are each derived from one type
of atom. If we were dealing with ions that
contain more than one type of atom, we would be dealing with polyatomic ions, like
NH4+, also known as the ammonium ion, or NO3−, also known as the nitrate ion. When writing chemical names for
mononuclear ionic compounds, the first rule is that the cation’s name goes first,
with monoatomic cations like calcium having the same name as their element name
found on the periodic table. So in this case, the first part of
the name for this compound will be calcium because the calcium ion is the
cation.
Once the cation’s name has been
written, it is followed by the anion name, which for monoatomic anions like the
fluorine ion contains the root of the element name followed by the suffix -ide. The root of the element named
fluorine is F-L-U-O-R, and we will follow it up with -ide to obtain the anion name
of fluoride. If a cation can form multiple
charges, the charge number is indicated after the element name by the Roman numeral
that matches the charge value. For example, the name for the
copper one plus cation is copper, followed by the Roman numeral one in
parentheses. Since calcium ions only form two
plus charges, a Roman numeral is not needed in this chemical name. Therefore, the name of the ionic
compound of calcium and fluorine is calcium fluoride.
