Part A K+ and Se2- Express your answer as a chemical formula. A chemical reaction does not occur for this question. Part B Ga3+ and Cl- Express your answer as a chemical formula. Part C A chemical reaction does not occur for this question. Ca2+ and P3- Express your answer as a chemical formula. Part D A chemical reaction does not occur for this question. Sc3+ and O2- Express your answer as a chemical formula. Part E A chemical reaction does not occur for this question. Sr2+ and As3- Express your answer as a chemical formula. A chemical reaction does not occur for this question
The Correct Answer and Explanation is:
Part A:
K⁺ and Se²⁻ → K₂Se
Part B:
Ga³⁺ and Cl⁻ → GaCl₃
Part C:
Ca²⁺ and P³⁻ → Ca₃P₂
Part D:
Sc³⁺ and O²⁻ → Sc₂O₃
Part E:
Sr²⁺ and As³⁻ → Sr₃As₂
Explanation:
When forming ionic compounds, the total positive charge from the cations (positively charged ions) must balance the total negative charge from the anions (negatively charged ions). The chemical formula represents the simplest whole-number ratio of ions needed to achieve electrical neutrality.
In Part A, potassium (K⁺) is a Group 1 metal and forms a +1 ion. Selenium (Se²⁻) forms a -2 anion. To balance the charges, two K⁺ ions are needed for every one Se²⁻ ion, resulting in K₂Se.
In Part B, gallium (Ga³⁺) forms a +3 ion, and chloride (Cl⁻) forms a -1 ion. Three Cl⁻ ions are required to balance one Ga³⁺ ion. Therefore, the formula is GaCl₃.
In Part C, calcium (Ca²⁺) and phosphorus (P³⁻) combine in a 3:2 ratio to balance the charges: three Ca²⁺ (total +6) and two P³⁻ (total -6) yield the neutral compound Ca₃P₂.
In Part D, scandium (Sc³⁺) and oxide (O²⁻) form Sc₂O₃ to balance the charges: two Sc³⁺ ions (total +6) and three O²⁻ ions (total -6).
In Part E, strontium (Sr²⁺) and arsenide (As³⁻) also require a 3:2 ratio. Three Sr²⁺ ions (+6) balance two As³⁻ ions (-6), forming Sr₃As₂.
These compounds are ionic because they are formed through the transfer of electrons from metals (which lose electrons to form cations) to nonmetals (which gain electrons to form anions). The resulting electrostatic attraction between oppositely charged ions holds the compound together. The chemical formula of each compound reflects the smallest whole-number ratio of ions that achieves charge neutrality.
