4: Compounds and Molecules
- Page ID
- 279974
Chemical Compounds
Exercise \(\PageIndex{1.a}\)
Using the periodic table, predict whether the following chlorides are ionic or covalent: KCl, NCl3, ICl, MgCl2, PCl5, and CCl4.
- Answer
-
Ionic: KCl, MgCl2
Covalent: NCl3, ICl, PCl5, CCl4
Exercise \(\PageIndex{1.b}\)
Using the periodic table, predict whether the following chlorides are ionic or covalent: KCl, NCl3, ICl, MgCl2, PCl5, and CCl4.
- Answer
-
Ionic: KCl, MgCl2
Covalent: NCl3, ICl, PCl5, CCl4
Exercise \(\PageIndex{1.c}\)
For each of the following compounds, state whether it is ionic or covalent. If it is ionic, write the symbols for the ions involved:
- NF3
- BaO
- IBr
- Na2O
- Answer a
-
covalent
- Answer b
-
ionic, Ba2+, O−2
- Answer c
-
covalent
- Answer d
-
ionic, Na+, O−2
Molecular Compounds
Exercise \(\PageIndex{2.a}\)
Explain why the symbol for an atom of the element oxygen and the formula for a molecule of oxygen differ.
- Answer
-
The symbol for the element oxygen, O, represents both the element and one atom of oxygen. A molecule of oxygen, O2, contains two oxygen atoms; the subscript 2 in the formula must be used to distinguish the diatomic molecule from two single oxygen atoms.
Ionic Compounds and Formulas
Exercise \(\PageIndex{3.a}\)
For each of the following pairs of ions, write the formula of the compound they will form:
- Ca2+, S2−
- \(NH_{4}^{+}\), \(SO_{4}^{2-}\)
- Al3+, Br−
- Na+, \(HPO_{4}^{2-}\)
- Mg2+, \(PO_{4}^{3-}\)
- Answer a
-
CaS
- Answer b
-
(NH4)2SO4
- Answer c
-
AlBr3
- Answer d
-
Na2HPO4
- Answer e
-
Mg3(PO4)2
Polyatomic Ions
Nomenclature
Exercise \(\PageIndex{5.a}\)
Name the following compounds:
- CsCl
- BaO
- K2S
- BeCl2
- HBr
- AlF3
- Answer a
-
cesium chloride
- Answer b
-
barium oxide
- Answer c
-
potassium sulfide
- Answer d
-
beryllium chloride
- Answer e
-
hydrogen bromide
- Answer f
-
aluminum fluoride
Exercise \(\PageIndex{5.b}\)
Each of the following compounds contains a metal that can exhibit more than one ionic charge. Name these compounds:
- Cr2O3
- FeCl2
- CrO3
- TiCl4
- CoO
- MoS2
- Answer a
-
chromium(III) oxide
- Answer b
-
iron(II) chloride
- Answer c
-
chromium(VI) oxide
- Answer d
-
titanium(IV) chloride
- Answer e
-
cobalt(II) oxide
- Answer f
-
molybdenum(IV) sulfide
Exercise \(\PageIndex{5.c}\)
Write the formulas of the following compounds:
- rubidium bromide
- magnesium selenide
- sodium oxide
- calcium chloride
- hydrogen fluoride
- gallium phosphide
- aluminum bromide
- ammonium sulfate
- Answer a
- RbBr
- Answer b
- MgSe
- Answer c
- Na2O
- Answer d
- CaCl2
- Answer e
- HF
- Answer f
- GaP
- Answer g
- AlBr3
- Answer h
- (NH4)2SO4
Exercise \(\PageIndex{5.d}\)
Write the formulas of the following compounds:
- chlorine dioxide
- dinitrogen tetraoxide
- potassium phosphide
- silver(I) sulfide
- aluminum nitride
- silicon dioxide
- Answer a
- ClO2
- Answer b
- N2O4
- Answer c
- K3P
- Answer d
- Ag2S
- Answer e
- AlN
- Answer f
- SiO2
Exercise \(\PageIndex{5.e}\)
The following ionic compounds are found in common household products. Write the formulas for each compound:
- potassium phosphate
- copper(II) sulfate
- calcium chloride
- titanium dioxide
- ammonium nitrate
- sodium bisulfate (the common name for sodium hydrogen sulfate)
- Answer a
- K3PO4
- Answer b
- CuSO4
- Answer c
- CaCl2
- Answer d
- TiO2
- Answer e
- NH4NO3
- Answer f
- NaHSO4