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
Define
covalent bond.
the electrostatic attraction between a shared pair of electrons
(and the nuclei of two bonded atoms)
- no electron transfer
- ions share electrons
What elements exist as
diatomic molecules?
Hydrogen
Nitrogen
Fluorine
Oxygen
Iodine
Chlorine
Bromine
Have No Fear Of Ice Cold Beer
What are the electrons that are not being shared referred to as in covalent bonds?
lone electrons
(or lone pairs)
Define
molecule.
a particle consisting of two or more atoms joined together by covalent bonding
What are the key properties of
simple covalent molecules?
- very strong covalent bonds within molecules
- very weak intermolecular attractions between molecules
- low melting and boiling points
- cannot conduct electricity
Define
intermolecular forces.
the attraction between neighbouring molecules
Why do simple covalent molecules have
low melting and boiling points?
- there are very weak intermolecular attractions between molecules
- these require very little energy to be broken
Why can’t simple covalent molecules conduct electricity?
- 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
- covalent molecules do not have either of these
- so cannot carry current
(graphite is an exception)
What are the
carbon allotropes?
- diamond
- graphite
- buckminsterfullerene
Define
giant covalent structures.
huge networks of atoms held together by covalent bonds
Define
allotrope.
different forms of the same element
What are the characteristics and properties of
diamond?
- giant structure
- made up of covalent bonds
- strong covalent bonds
- each carbon atoms is bonded to 4 others
. - high melting and boiling points
- very hard
- insoluble
- does not conduct electricity
What are the characteristics and properties of
graphite?
- giant structure
- made up of covalently bonded layers
- strong covalent bonds
- weak intermolecular forces between layers
- each carbon atom is bonded to 3 others
. - high melting and boiling points
- soft and slippery
- insoluble
- can conduct electricity
What are the characteristics and properties of
buckminsterfullerene?
- giant molecule
- made up of covalent bonds
- strong covalent bonds
- each carbon is bonded to 3 others
. - black solid
- insoluble
- semi-conductor (can conduct within molecule)
