Ionic Formulas-Polyatomic an Ionic Compound Is a Chemical Compound Comprising Ions Held Together by Electrostatic Forces Termed Ionic Bonding

NTI Day 3

Focus Standard. I can write formulas and name ionic compounds. Ionic Formulas-Polyatomic An ionic compound is a chemical compound comprising ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions. These can be simple ions such as the sodium (Na+) and chloride(Cl−) in sodium chloride, NaCl, or polyatomic species such as + 2− the ammonium (NH4 ) and carbonate (CO3 ) ions in ammonium carbonate (NH4)2CO3. Ionic compounds form when elements, or polyatomic ions, have a large difference in electronegativities. Electrons from one species is transferred to another, resulting in oppositely charged ions that attract to each other. Writing Ionic Formula Notes: 1. Write first element and its oxidation number (charge); if first element is a transition metal, the Roman numeral will indicate the charge. 2. Write second element/group of elements (polyatomic) and its oxidation number. 3. If oxidation #s add to zero, cancel them; if not, switch For more examples of how to write formulas of ionic compounds with polyatomic ions, pull your work from your notes. Additional examples can be viewed in this tutorial. https://www.youtube.com/watch?v=p9iQ5Qn42DM

Multiple Choice Identify the choice that best completes the statement or answers the question.

1. What is the formula for ammonium oxide?

(a) NH4O (b) (NH4)2O (c) (NH4)O2 (d) (NH2)O4

2. What is the formula for iron (III) nitrate?

(a) Fe(NO3) (b) Fe3(NO3) (c) Fe(NO3)2 (d) Fe(NO3)3

3. What is the formula for calcium hydroxide?

(a) CaOH2 (b) CaH2 (c) Ca(OH)2 (d) CaOH

4. What is the formula for strontium cyanide?

(a) SrCN (b) SrCN2 (c) SrC2 (d) Sr(CN)2

5. What is the formula for ammonium hydroxide?

(a) NH4H (b) NH4OH (c) NH(OH)4 (d) NH4O NTI Day 3

6. What is the formula for lithium nitrate?

(a) Li2NO3 (b) LiNO3 (c) Li(NO3)2 (d) Li3NO

7. What is the formula for potassium hydroxide?

(a) K2H (b) K(OH)2 (c) KH (d) KOH

8. What is the formula for ammonium bromide?

(a) NHBr4 (b) NH4Br2 (c) (NH4)2Br (d) NH4Br

9. What is the formula for beryllium phosphate?

(a) Be4PO2 (b) Be3(PO4)2 (c) Be3P2 (d) Be3P

10. What is the formula for Sodium carbonate?

(a) Na3CO (b) Na2(CO)3 (c) Na2CO3 (d) NaCO3

11. What is the formula for strontium sulfate?

(a) SrSO4 (b) Sr2(SO4)2 (c) Sr2SO4 (d) SrS

12. What is the formula for aluminum phosphate?

(a) Al3(PO4) (b) AlPO4 (c) Al(PO)4 (d) Al3(PO4)3

13. What is the formula for sodium cyanide?

(a) NaCN2 (b) Na2CN (c) NaCN (d) Na3CN2

14. What is the formula for ammonium nitrate?

(a) NH4NO3 (b) (NH4)3NO (c) NH3NO4 (d) NH(NO3)4

15. What is the formula for aluminum carbonate?

(a) Al3(CO3)2 (b) Al(CO3) (c) Al2(CO3)3 (d) Al2(CO)3