Polyatomic Ions
Concept Map
Polyatomic ions are clusters of covalently bonded atoms with a net charge, crucial in forming various compounds. Examples like sulfate (SO4^2-) and nitrate (NO3^-) illustrate their stability in solutions and the importance of their nomenclature for clear chemical communication. Understanding their oxidation states is key to determining their charge and reactivity, making them fundamental in chemical reactions.
Summary
Outline
Understanding Polyatomic Ions
Polyatomic ions are composed of two or more atoms covalently bonded together that carry a net positive or negative charge. These ions are distinct from monatomic ions, which consist of single atoms with a charge. Polyatomic ions, such as the sulfate ion (SO4^2-), remain bonded as a unit in solution, contrasting with ionic compounds like sodium chloride (NaCl), which dissociate into individual ions (Na+ and Cl-) when dissolved.Examples and Characteristics of Polyatomic Ions
An example of a polyatomic ion is the carbonate ion (CO3^2-), which carries a -2 charge and forms stable ionic compounds, such as calcium carbonate (CaCO3). The carbonate ion exhibits resonance, where the double bonds between the carbon and oxygen atoms are delocalized, effectively creating bonds that are a mixture between single and double bonds. Polyatomic ions can also form compounds with each other, as seen in ammonium carbonate ((NH4)2CO3), where two ammonium ions (NH4+) bond with a single carbonate ion.Nomenclature of Compounds Containing Polyatomic Ions
The nomenclature for ionic compounds containing polyatomic ions involves naming the cation first, followed by the anion. Polyatomic ions have specific names that do not change based on the number present in the compound. When multiple polyatomic ions are needed to balance the charge in a compound, parentheses are used to enclose the polyatomic ion's formula, with a subscript outside the parentheses indicating the number of ions, as in aluminum sulfate (Al2(SO4)3).Common Polyatomic Ions and Their Nomenclature
Common polyatomic ions include sulfate (SO4^2-), nitrate (NO3^-), and phosphate (PO4^3-). These ions are memorized by students for their names and charges. Oxyanions, a type of polyatomic ion containing oxygen, have names that vary with the number of oxygen atoms: "per" indicates the most oxygen, "ate" indicates a standard amount, "ite" indicates fewer, and "hypo" indicates the fewest, as in perchlorate (ClO4^-), chlorate (ClO3^-), chlorite (ClO2^-), and hypochlorite (ClO^-).Determining the Charge of Polyatomic Ions
The charge of a polyatomic ion is determined by the oxidation states of its constituent atoms. Oxidation states are assigned based on an atom's electronegativity and its hypothetical ionic charge in a compound. For instance, in the nitrate ion (NO3^-), oxygen has an oxidation state of -2, and nitrogen typically has an oxidation state of +5. The sum of the oxidation states equals the overall charge of the ion.Key Takeaways on Polyatomic Ions
Polyatomic ions are essential in chemistry as they form a wide variety of compounds and participate in numerous chemical reactions. They are characterized by their covalent bonds within the ion and their ability to remain intact in solution. Properly naming compounds containing polyatomic ions is crucial for clear communication in chemistry. Additionally, understanding the oxidation states of the elements within a polyatomic ion is vital for determining its charge and predicting its reactivity and interactions with other ions.
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Definition of Polyatomic Ions
Composition of Polyatomic Ions
Polyatomic ions are composed of two or more atoms covalently bonded together that carry a net positive or negative charge
Distinction from Monatomic Ions
Polyatomic ions are distinct from monatomic ions, which consist of single atoms with a charge
Behavior in Solution
Polyatomic ions remain bonded as a unit in solution, unlike ionic compounds which dissociate into individual ions when dissolved
Examples of Polyatomic Ions
Carbonate Ion
The carbonate ion carries a -2 charge and exhibits resonance, forming stable ionic compounds such as calcium carbonate
Ammonium Carbonate
Ammonium carbonate is an example of a compound formed by the bonding of two ammonium ions with a single carbonate ion
Common Polyatomic Ions
Common polyatomic ions include sulfate, nitrate, and phosphate, which are memorized by students for their names and charges
Nomenclature of Polyatomic Ions
Naming Conventions
Polyatomic ions have specific names that do not change based on the number present in the compound, and are named by listing the cation first followed by the anion
Parentheses and Subscripts
When multiple polyatomic ions are needed to balance the charge in a compound, parentheses are used to enclose the ion's formula, with a subscript indicating the number of ions
Oxyanions
Oxyanions, a type of polyatomic ion containing oxygen, have names that vary based on the number of oxygen atoms present
Charge and Reactivity of Polyatomic Ions
Determining Charge
The charge of a polyatomic ion is determined by the oxidation states of its constituent atoms, which are assigned based on electronegativity and hypothetical ionic charge
Importance in Chemistry
Polyatomic ions are essential in chemistry as they form a wide variety of compounds and participate in numerous chemical reactions
Communication and Understanding
Properly naming compounds containing polyatomic ions and understanding the oxidation states of the elements within them is crucial for clear communication and predicting their reactivity and interactions with other ions
Polyatomic Ions
Learn with Algor Education flashcards
Click on each Card to learn more about the topic
00
Unlike ______ ions that are single charged atoms, ______ ions like sulfate (SO4^2-) stay bonded in solution.
monatomic
polyatomic
01
Charge of carbonate ion
Carbonate ion (CO3^2-) carries a -2 charge.
02
Resonance in carbonate ion
Carbonate ion exhibits resonance with delocalized double bonds, creating a mix between single and double bonds.
