25 Questions
Which type of compounds result when atoms share electrons instead of transferring them?
Molecular compounds
What is the formula for sodium oxalate when reduced to its empirical formula?
NaCO2
Which compound is predicted to be ionic based on the periodic table positions of its elements: KI, H2O2, CHCl3, or Li2CO3?
KI
Under normal conditions, what are the common physical states for molecular compounds?
Low-boiling liquids
Which of the following compounds contains only monatomic ions: NaCl, CaSO4, H2O2, or CHCl3?
NaCl
Why is the empirical formula NaCO2 not accepted for sodium oxalate?
It does not represent the compound's polyatomic anion accurately.
What type of bonding characterizes molecular compounds?
Covalent bonding
Which compound is predicted to be molecular based on the periodic table positions of its elements: KI, H2O2, CHCl3, or Li2CO3?
H2O2
What is the common physical state for molecular compounds under normal conditions?
Low-boiling liquids
Which compound contains only monatomic ions?
NaCl
What is the predicted type of bonding for CaF2 based on the positions of its elements in the periodic table?
Ionic
Which compound is incorrectly matched with its predicted type of bonding based on the periodic table positions: KI, H2O2, CHCl3, or Li2CO3?
CHCl3 - Molecular
What is the physical state of many molecular compounds under normal conditions?
Gases
Why can't the formula NaCO2 be accepted as the formula for sodium oxalate?
It does not accurately represent the compound's polyatomic anion C2O42−.
Which group of elements usually form covalent compounds?
Metals and nonmetals
What are the common physical states for ionic compounds under normal conditions?
High-melting solids
Based on the periodic table, which of the following compounds is predicted to be molecular: NaCl, CaSO4, H2O2, or CHCl3?
H2O2
What is the formula for sodium oxalate when written in its non-empirical form?
Na2C2O4
Why are some ionic compound formulas not empirical formulas?
Their subscripts are not the smallest-possible whole numbers.
What process leads to the formation of molecular compounds?
Electron sharing
What is the difference between ionic and molecular compounds?
Ionic compounds contain ions and are formed by the transfer of electrons, while molecular compounds consist of neutral molecules formed by the sharing of electrons.
Explain the concept of covalent bonding in molecular compounds.
Covalent bonding in molecular compounds occurs when atoms share electrons rather than transferring them.
Why are some ionic compound formulas not empirical formulas?
Some ionic compound formulas are not empirical because the subscripts in their formulas are not the smallest-possible whole numbers.
How can we predict the type of bonding in compounds using the periodic table?
By looking at the positions of the elements in the periodic table, we can predict whether a compound is ionic or molecular.
What are the common physical states for molecular compounds under normal conditions?
Under normal conditions, molecular compounds often exist as gases, low-boiling liquids, and low-melting solids.
Study Notes
Atomic Structure and Ionic Compounds
- In ordinary chemical reactions, the nucleus of each atom remains unchanged, but electrons can be added, lost, or shared with other atoms.
- The transfer and sharing of electrons among atoms govern the chemistry of elements.
Ions and Ionic Compounds
- Atoms can gain or lose electrons to form electrically charged particles called ions.
- Ions can be formed by:
- Metals (Group 1-2) losing electrons to form cations with positive charges.
- Nonmetals (Group 17-18) gaining electrons to form anions with negative charges.
- The periodic table can be used to predict the formation of ions and their charges.
Main-Group Elements and Ionic Charges
- Metals in Group 1-2 lose electrons to form cations with charges equal to the group number.
- Nonmetals in Group 17-18 gain electrons to form anions with charges equal to the number of groups moved left from the noble gases.
Polyatomic Ions
- Polyatomic ions are electrically charged molecules that act as discrete units.
- Some common polyatomic ions include:
- Oxyanions (contain oxygen atoms): peroxide (O22-), hydroxide (OH-), etc.
- Other polyatomic ions: ammonium (NH4+), acetate (CH3COO-), etc.
Naming Polyatomic Ions
- Polyatomic ions are named using suffixes and prefixes:
- -ate and -ite suffixes indicate polyatomic ions with more or fewer oxygen atoms.
- Per- (hyper) and hypo- prefixes indicate more or fewer oxygen atoms.
Ionic Compounds
- Ionic compounds are formed when a metal reacts with a nonmetal.
- Ionic compounds are stabilized by electrostatic attractions between cations and anions.
- Properties of ionic compounds:
- Solids that melt at high temperatures and boil at even higher temperatures.
- Electrically conductive when molten, but not in solid form.
- Formula of an ionic compound must have a ratio of ions that balances the positive and negative charges.
Predicting the Formula of an Ionic Compound
- The formula of an ionic compound can be predicted by:
- Balancing the positive and negative charges.
- Using the periodic table to predict the charge on the ions.
- Treating polyatomic ions as discrete units.
Examples of Ionic Compounds
- Sodium chloride (NaCl): formed from the reaction of sodium metal (Group 1) and chlorine gas (Group 17).
- Calcium phosphate (Ca3(PO4)2): formed from the reaction of calcium metal (Group 2) and phosphate ions (PO43-).### Ionic Compounds and Molecular Compounds
- Ionic compounds:
- Contain ions (cations and anions) held together by electrostatic forces (ionic bonds)
- Formed when metals (group 1-2) react with nonmetals (group 16-17)
- Typically solids with high melting and boiling points
- Not electrically conductive in solid form, but conductive when molten
- Molecular compounds (covalent compounds):
- Composed of discrete, neutral molecules
- Formed by sharing electrons between nonmetal atoms
- Typically low-boiling liquids or gases
- Not electrically conductive
Predicting Ionic or Molecular Compounds
- Use the periodic table to predict:
- Metals (group 1-2) usually form ionic compounds with nonmetals
- Nonmetals (group 14-17) usually form molecular compounds with other nonmetals
- Exceptions: transition metals and some metals can form molecular compounds
Ions and Ion Formation
- Atoms gain or lose electrons to form ions
- Metals tend to lose electrons to form cations (positive ions)
- Nonmetals tend to gain electrons to form anions (negative ions)
- Cations and anions combine in a ratio to form ionic compounds
Polyatomic Ions
- Formed by groups of bonded atoms with an overall charge
- Act as discrete units in ionic compounds
- Examples: ammonium (NH4+), sulfate (SO42-), carbonate (CO32-)
Writing Formulas for Ionic Compounds
- The total number of positive charges must equal the total number of negative charges
- Use parentheses to indicate polyatomic ions
- Examples: Ca3(PO4)2, Na2S, Al2O3### Ionic Compounds and Molecular Compounds
- Ionic compounds:
- Contain ions (cations and anions) held together by electrostatic forces (ionic bonds)
- Formed when metals (group 1-2) react with nonmetals (group 16-17)
- Typically solids with high melting and boiling points
- Not electrically conductive in solid form, but conductive when molten
- Molecular compounds (covalent compounds):
- Composed of discrete, neutral molecules
- Formed by sharing electrons between nonmetal atoms
- Typically low-boiling liquids or gases
- Not electrically conductive
Predicting Ionic or Molecular Compounds
- Use the periodic table to predict:
- Metals (group 1-2) usually form ionic compounds with nonmetals
- Nonmetals (group 14-17) usually form molecular compounds with other nonmetals
- Exceptions: transition metals and some metals can form molecular compounds
Ions and Ion Formation
- Atoms gain or lose electrons to form ions
- Metals tend to lose electrons to form cations (positive ions)
- Nonmetals tend to gain electrons to form anions (negative ions)
- Cations and anions combine in a ratio to form ionic compounds
Polyatomic Ions
- Formed by groups of bonded atoms with an overall charge
- Act as discrete units in ionic compounds
- Examples: ammonium (NH4+), sulfate (SO42-), carbonate (CO32-)
Writing Formulas for Ionic Compounds
- The total number of positive charges must equal the total number of negative charges
- Use parentheses to indicate polyatomic ions
- Examples: Ca3(PO4)2, Na2S, Al2O3
Test your knowledge of common polyatomic ions and their related acid formulas with this quiz. Identify the name and formula of polyatomic ions like ammonium, hydroxide, sulfate, and more.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
