Ch5.5 Flashcards
(24 cards)
What type of formula do ionic compounds have?
Empirical formulas, showing the lowest whole-number ratio of ions.
How do you write an ionic formula from two ions?
Balance the charges so the total positive equals the total negative, then use subscripts.
What is the crisscross method in writing ionic formulas?
Cross the charge numbers (ignore signs) to become subscripts for the opposite ions.
Write the formula for aluminum nitride using charges.
Al³⁺ and N³⁻ = AlN
Write the formula for lithium oxide using the crisscross method.
Li⁺ and O²⁻ = Li₂O
What are polyatomic ions?
Charged groups of atoms that act as a single ion (e.g., NO₃⁻ = nitrate).
When are parentheses used in ionic formulas?
When there’s more than one polyatomic ion (e.g., Ca(NO₃)₂).
Write the formula for calcium nitrate.
Ca²⁺ and NO₃⁻ = Ca(NO₃)₂
How can you recognize an ionic compound?
It usually has a metal and nonmetal or includes a polyatomic ion.
Classify: Na₂O
Ionic (metal + nonmetal).
Classify: PCl₃
Not ionic (two nonmetals).
Classify: NH₄Cl
Ionic (contains ammonium ion).
What type of formula do ionic compounds have?
Empirical formulas, showing the lowest whole-number ratio of ions.
How do you write an ionic formula from two ions?
Balance the charges so the total positive equals the total negative, then use subscripts.
What is the crisscross method in writing ionic formulas?
Cross the charge numbers (ignore signs) to become subscripts for the opposite ions.
Write the formula for aluminum nitride using charges.
Al³⁺ and N³⁻ = AlN
Write the formula for lithium oxide using the crisscross method.
Li⁺ and O²⁻ = Li₂O
What are polyatomic ions?
Charged groups of atoms that act as a single ion (e.g., NO₃⁻ = nitrate).
When are parentheses used in ionic formulas?
When there’s more than one polyatomic ion (e.g., Ca(NO₃)₂).
Write the formula for calcium nitrate.
Ca²⁺ and NO₃⁻ = Ca(NO₃)₂
How can you recognize an ionic compound?
It usually has a metal and nonmetal or includes a polyatomic ion.
Classify: Na₂O
Ionic (metal + nonmetal).
Classify: PCl₃
Not ionic (two nonmetals).
Classify: NH₄Cl
Ionic (contains ammonium ion).
