section 3: compound names and formulas
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Section 3: COMPOUND NAMES AND FORMULAS. How are ionic compounds named ? What do the numerical prefixes used in naming covalent compounds tell you ? What does a compound´s empirical formula indicate ?. Key Ideas. Key Terms. - PowerPoint PPT PresentationTRANSCRIPT
SECTION 3: COMPOUND NAMES
AND FORMULAS
KEY IDEAS
How are ionic compounds named? What do the numerical prefixes used in
naming covalent compounds tell you? What does a compound´s empirical
formula indicate?
KEY TERMS
Empirical formula
Anion
Molecular formula
Cation
NAMING IONIC COMPOUNDS
The names of ionic compounds consist of the names of the ions that make up the compounds
Name of cations include the elements of which they are composed
Ion name and symbol
Cesium ion, Cs+
Lithium ion, Li+
Sodium ion, Na+
Barium ion, Ba2+
Calcium ion, Ca2+
Aluminum ion, Al3+
Ion charge
1+ 2+ 3+
NAMING IONIC COMPOUNDS
Names of anions are altered names of elements NaF: is made of sodium ions, Na+, and fluoride
ions, F-. Therefore, its name is sodium fluoride An ionic compound must have a total
charge of zero If an ionic compound is made up of ions that
have different charges, the ratio will not be 1:1 For calcium fluoride to have a total charge of
zero, there must be two fluoride ions for every calcium ion
NAMING IONIC COMPOUNDS
Some cation names must show their charge The charge of the iron cation in Fe2O3 is
different from the charge of the iron cation in FeO. In cases such as this, the cation name must be followed by a Roman numeral in parentheses that shows the cation’s charge.
Fe2O3 is made of Fe3+ ions, so it is named iron (III) oxide. FeO is made of Fe2+ ions, so it is named iron (II) oxide.
NAMING IONIC COMPOUNDS
Determine the charge of a transition metal cation How can you tell that the iron ion in Fe2O3 has a
charge of 3+? Write formulas for ionic compound using
names You can find the charge of each ion in a
compound if you are given the compound’s formula. You can find the formula for a compound if you are given the compound’s name
NAMING IONIC COMPOUNDS
Math Skills: Writing Ionic Formulas Go to go.hrw.com and enter keyword
HK8MP
NAMING COVALENT COMPOUNDS
For covalent compounds or two elements, numerical prefixes tell how many atoms of each element are in the molecule
Numerical prefixes are used to name covalent compounds of two elements If there is only one atom of the first element,
the name does not get a prefix The element farther to the right in the periodic
table is named second and ends in –ide One boron atom and three fluorine atoms
make up boron trifluoride, BF3
EMPIRICAL FORMULAS
An empirical formula tells us the smallest whole-number ratio of atoms that are in a compound
Different compounds can have same empirical formula
Molecular formulas are determined from empirical formulas
Masses can be used to determine empirical formulas
EMPIRICAL FORMULAS
Empirical formula: the composition of a compound in terms of the relative number and kinds of atoms in the simplest ratio
Molecular formula: a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrengement of atoms
EMPIRICAL FORMULAS
Math Skills: Finding Empirical Formulas Go to go.hrw.com and enter keyword
HK8MP
HOMEWORK