Bonding and Structure Flashcards
What is the ion formula of the polyatomic ion
ammonium?
NH4+
What is the ion formula of the polyatomic ion
nitrate?
NO3-
What is the ion formula of the polyatomic ion
hydroxide?
OH-
What is the ion formula of the polyatomic ion
carbonate?
CO32-
What is the ion formula of the polyatomic ion
sulfate?
SO42-
What is the ion formula of the polyatomic ion
sulfite?
SO32-
What is the ion formula of the polyatomic ion
phosphate?
PO43-
What is the
structure of an ionic compound?
a giant ionic lattice
Why are ionic compounds lattice structures?
- there are strong electrostatic forces between oppositely charged ions
- these forces act in all directions
- this results in positive ions being immediately surrounded by negative ions and vice versa
- this repeating pattern in 3D gives ionic compounds a regular giant lattice structure
What are the
key properties of ionic compounds?
- high melting and boiling points
- conduct electricity when molten or aqueous
- brittle
Why do ionic compounds have
high melting and boiling points?
- there are a large number of strong electrostatic attractions between the negative and positive ions
- so large amounts of energy are needed to overcome these forces
- so high temperatures (with lots of energy) are necessary to convert between states
Why do ionic compounds
conduct electricity when molten or aqueous but not when solid?
- in order for a material to conduct electricity it needs to be able to carry current
- current is just the flow of charge
- so the material needs either delocalised electrons or free ions
- in ionic compounds there are no delocalised electrons
- when solid, the ions in ionic compounds cannot move so cannot carry current
- when liquid (molten) and when aqueous, the ions in ionic compounds can move so can carry current
Why are ionic compounds
brittle?
Because if the rows of alternating ions are shifted even slightly, then the ions will no longer be alternating. This means that there will be positive ions next to each other and negative ions next to eachother. These opposite charges repel and the compound breaks or ‘splinters’.
What elements are used in
ionic bonding?
1 that forms a negative ion
and
1 that forms a positive ion
(so mostly a metal and a non-metal)
What elements are used in
covalent bonding?
non-metals only