CHE - Ionic Bonding Flashcards
Why do ionic compounds have high melting points?
Strong electrostatic attraction between cations and anions (high temps required to break these bonds and change the state)
Why are ionic compounds hard and brittle?
Strong bonds > dense > hardness
If strong force is applied, the crystal breaks and the cations will be moved to in line with the cations (same w/ anions) and the like charges will repel and shatter the crystal
Why can’t ionic compounds conduct electricity in solid form?
Ions held in crystal lattice and are not free to move and carry the electrical charge
Why can molten or aqueous ionic compounds conduct electricity?
Ions free to move to electrodes and carry the electrical charge
What are polyatomic ions?
Ions with more than one atom
What is electrovalency?
The charge of an ion
Name common uses for ionic compounds.
- Marble (CaCO3) is hard and strong, almost insoluble in water, buildings and statues last a long time
- Calcium phosphate (Ca3(PO4)2) is present in bones for strength
- Rocks and clays (strength)
- Provide ions in solution to conduct electric currents
- Sodium hydrogen carbonate (NaHCO3) is used for baking (aka bicarbonate of soda) as it decomposes when heated and produces gas CO2 forming bubbles in cakes that cause them to rise, combined with Potassium Hydrogen Tartrate for baking powder, found in antacids and soluble painkillers,
- NaF an CaF2 are added to domestic water supplies b/c fluoride ion released in solution is thought to reduce tooth decay
- Ammonium Sulfate and Ammonium Nitrate are found in fertilisers as they dissolve in water and release ions containing nitrogen which can be absorbed by plants
What are the properties of ionic compounds?
Metals + Non-metals
High melting / boiling points
Hard
Brittle
Do not conduct electricity in solid state
Do conduct electricity in molten or aqueous state
