different structures Flashcards
Giant ionic structures
occurs between metal and non metal atoms
results in formation of metal compounds/ionic compounds
involves electron transfer from metal atom to non metal atom
charged particles called ions are produced by this electron transfer
oppositely charged ions attract each other to form an ionic bond
strong and require substantial energy to break.
properties of ionic substances
high melting point and boiling point- substantial energy is needed to break the strong ionic bonds between the oppositely charged ions
electrical conductivity- cannot conduct when solid because the ions cannot move and carry charge
can conduct when in aqueous solution- when dissolved in water the ions can move and carry charge
Covalent bonding
type of bonding is found in non metallic elements and compounds
both of the non metal atoms need to gain electrons to have a full outer shell
covalent bonds are formed by a shared pair of electrons
they are very strong and require large amounts of energy to break them
molecular covalent
occurs between non metal atoms only
atoms achieve a full outer shell by sharing electrons
a shared pair of electrons is known as a single covalent bond
very strong and require large amounts of energy to break
physical properties of molecular covalent substances
low melting points as little energy is needed to break the weak van der Waal’s forces of attraction between molecules
they do not conduct electricity because there are no charged particles to move and carry the charge
Carbon(diamond)
each carbon atom is covalently bonded to 4 others
leads to a giant, 3D tetrahedral structure of carbon atoms
these very strong covalent bonds extend throughout the structure
properties of carbon( Diamond)
very high boiling/melting point- Substantial energy is needed to break the strong covalent bonds throughout the 3D Tetrahedral structure
very hard- very strong covalent bonds throughout a rigid 3D structure
does not conduct electricity- No delocalized electrons free to move and carry charge
carbon(graphite)
each carbon atom is only bonded to 3 others by strong covalent bonds
atoms are arranged in hexagonal layers
the 4th outer shell electron from each carbon atom becomes delocalized and is free to move throughout the structure
these delocalized electrons can cause weak der Waals forces to form in between layers
graphite properties
conducts electricity- delocalized electrons can move and carry charge
soft- layers can slide over each other as there are only weak forces of attraction between them
very high melting and boiling points- substantial energy is needed to break the strong covalent bonds between the carbon atoms
graphene
a single layer thick of graphite
strong covalent bonds between each carbon atom
the atoms are arranged in hexagons
2D
properties of graphene
strength- 100 times stronger than steel due to rigid structure of hexagons and the strong covalent bonds between the carbon atoms
conducts electricity- each carbon atom is only covalently bonded to 3 others meaning that each carbon atom has an unbonded electron that becomes delocalized. These delocalized electrons can move and carry charge
low density- made of a single layer of carbon atoms
flexible- layer of carbon atoms can bend without breaking the covalent bonds
transparent and can transmit 98 percent of light through it because it is very thin
metallic bonding
atoms are arranged in regular layers called a lattice. The outer shell electrons from the metal atoms become delocalized and free to move throughout the whole structure.
There is an attraction between the positively charged metal ions and the sea of delocalized electrons which hold the metallic structure together.
metals physical properties
Good conductors of electricity and heat- delocalized electrons can move and carry the charge
high melting point- substantial energy is needed to break the strong metallic bonds between the positive metal ions and delocalized electrons
malleable and ductile- due to sea of delocalized electrons, the layers of metal ions can slide over each other and rearrange without breaking the metallic bond
Alloys properties
an alloy will have metallic properties, but the properties are often better than original metals from which it was formed
alloys are often harder than the pure metals because some of the ions in the alloy are a different size from those of the main metal, this distorts the layers and makes it more difficult for the layers to slide past each other
