Topic 2 - ionic compounds Flashcards
Ionic compound
Oppositely charged ions are held together by electrostatic attraction.
Hydroxide
OH-
Nitrate
NO3 (-)
Ammonium
NH4 (+)
Sulfate
SO4 (2-)
Carbonate
CO3 (2-)
How to work out the formula of an ionic compound
1) Write the 2 ions
2) Swap the charges
3) Drop the charges
4) Simplify to lowest whole number ratio
Sodium Chloride structure
Giant ionic structure:
Regular structure
Cubic shape
Giant repeating pattern
Do ionic compounds dissolve in water
Most do as water molecules are polar, which can attract the positive and negative ions and break up the structure.
Do ionic compounds conduct electricity
When molten or dissolved as the ions are free to move around
Melting point of ionic compounds
HIGH melting points due to many strong electrostatic forces between oppositely charges ions. Lots of energy required to overcome these forces,
Why are ionic compounds brittle
Layers can slide, causing positive ions to align with positives and negative ions to align with negatives. They repel and the structure breaks apart.
How does charge affect strength of ionic bond
Bigger charge = stronger electrostatic attraction between ions.
How does size of ion affect strength of ionic bond
Smaller ion = stronger electrostatic attraction between ions. Smaller ions can pack together more closely.
Smaller ion and high charge means
High charge density
Evidence for charged particles
Electrolysis of copper(ii)chromate(vi) on wet paper.
