5.3 Ionic Bonding And Structure Flashcards
Define ionic bond
The electrostatic attraction that holds cations (+) and anions (-) together in ionic compounds.
Common cations
Metal ions - Na+, Ca2+, Al3+
Ammonium ions - NH4 +
Common anions
Non metal ions - Cl-, O2-
Polyatomic ions - NO3 -, SO4 2-
What do dot and cross diagrams show?
The electron transfer of outer electrons
What do the square brackets in dot and cross diagrams represent?
The charge and that the ions are seperate entities
Why are the inner shells not shown in dot and cross diagrams?
Because they’re full so they’re not involved
What do ionic compounds form?
Giant ionic lattices because each ion attracts oppositely charged ions in all directions.
Low or high melting and boiling points?
A large quantity of energy is needed to overcome the strong electrostatic attraction between ions, so they are both high
State at room temperature?
Solid due to high boiling point
What increases the compounds melting points?
Lattices containing ions with greater charges increase Melting point
Are ionic compounds soluble?
They are soluble in polar solvents, such as water.
Why may a compound not be able to dissolve?
Attraction increase with charge so ions with large charges may contain attractions that are too strong to be broken by polar molecules
Two processes involved in solubility?
The ionic lattice must be broken down
The solvent must then attract and surround the ions
When can a ionic compound conduct electricity?
Why?
When it is molten because the lattice has broken don so ions are now free to move as mobile charger carriers
When can’t ionic compounds conduct electricity?
Why?
When solid because ions are in fixed positions meaning that there are no mobile charger carriers
