COVALENT BONDING Flashcards
What is dative bonding also called? (1)
coordinate bonding
why is diamond a good thermal conductor? (1)
vibrations travel easily through the stiff lattice
what is dative covalent bonding? (1)
where both electrons come from one atom
how are dative bonds shown? (1)
by arrows
what are the properties of substances with molecular structures? (3)
-low melting points
-poor conductors of electricity
-don’t dissolve
why cant diamond be cut? (1)
its structure makes it refract light a lot which is why is sparkles
how are atoms held together by covalent bonds? (1)
by the electrostatic forces of attraction between the nuclei and the shared electrons
why won’t diamond dissolve in solvent? (1)
the covalent bonds are too strong to break
why won’t diamond conduct electricity? (1)
all the outer electrons are held in localised bonds
what happens in dative covalent bonding? (2)
-the atom accepts the electron pair is an atom that does not fill the outer main level of electrons (electron deficient)
-the atom that is donating the electrons has a pir of electrons that is not being used in a bond (lone pair)
why does diamond have a extremely hard structure? (1)
because of its rigid strong covalent structure (can be used in drills and saws)
what is the structure of diamond? (2)
-each carbon atom is covalently bonded to 4 other carbon atoms
-the atoms are arranged in a tetrahedral shape.
what are the properties of graphite? (5)
-layers
-carries a charge
-low density
-high melting point
-insoluble in any solvent
why does diamond have a high melting point? (1)
because of its strong covalent bonds and the energy that is needed to break them (sublimes over 3900K)
what are the properties of diamond? (6)
-high melting point
-extremely hard
-good thermal conductor
-can’t conduct electricity
-won’t dissolve in any solvent
-can’t be cut
why does graphite have a low density? (1)
because the layers are quite far apart compared to the length of covalent bonds hence it has a low density (used for light weight sports equipment)
why is graphite insoluble? (1)
the covalent bonds in the sheets are to strong to break.
why does graphite carry a charge? (1)
the delocalised electrons in graphite aren’t attached to any particular carbon and are free to move along the sheets carrying a charge (electrical conductor)
why does graphite have a high melting point? (1)
because of the strong covalent bonds in the hexagon sheets (sublimes over 3900K)
what does sublime mean? (1)
means to change straight from a solid to gas
what properties does graphite have because of its layers? (1)
the weak bonds between the layers in graphite are easily broken, so the sheets can slide over each other - feels slippery and can be used as a dry lubricant
how many pairs of electrons are shared in a triple covalent bond? (1)
3 pairs of electrons
what structures do covalent bonds form? (1)
giant covalent structures (sometimes called macromolar structures)
why do carbon atoms form a giant covalent structure? (1)
because they can form 4 strong covalent bonds
what are the types of giant covalent structures? (2)
-graphite
-diamond
what is covalent bonding? (1)
molecule formed when two or more atoms bond together (by strong covalent bonds) (atoms are non-metal)
how many pairs of electrons are shared in a single covalent bond? (1)
one pair of electrons
how many pairs of electrons are shared in a double covalent bond? (1)
two pairs of electrons
