covalent bonding Flashcards
when atoms share pairs of electrons what do they form?
covalent bonds
what is the definition of covalent bonding?
the strong electrostatic attraction between a shared pair of electrons and the protons in the nuclei
why do simple covalent bonds not conduct electricity?
they dont contain free electrons
why do simple molecular substances have a low melting and boiling point?
only weak intermolecular forces acting between the molecules
the intermolecular forces are usually what compared to the covalent bonds?
weak
most simple molecules are what at room temperature?
liquid or gas
as the molecules increase in size what happens to the intermolecular forces?
they also increase
the intermolecular forces increasing in size means what?
the melting and boiling points increase
are covalent structures good or bad conductors of energy?
bad as there are no free ions or electrons to carry the charge
the simple molecules contain what number of atoms?
fixed
giant covalent structures contain what number of atoms?
a huge number( a giant lattice)
diamond and graphite are what of carbon?
allotropes
in diamond, each carbon atoms forms with how many other carbon atoms?
4- forming a tetrahedron
what are the covalent bonds like in diamond?
identical, very strong and there are no intermolecular forces
what are diamonds physical properties?
very hard, has a very high melting point and it doesnt conduct electricity
does diamond have any freely charged particles?
no-therefore it cannot conduct electricity
what is a large amount of heat required to break?
the lattice
what are the atoms arrangements in silicon dioxide?
each oxygen atom forms covalent bonds with 2 silicon atoms and each silicon atom forms covalent bonds with 4 oxygen atoms
what is the tetrahedron in silicon dioxide formed by?
one silicon atom and 4 oxygen atoms
does silicon dioxide have covalent bonds?
yes lots of very strong covalent bonds
does silicon dioxide have intermolecular forces?
no
physical properties of silicon dioxide?
very high boiling point, insoluble in water and doesnt conduct electricity
why is silicon dioxide cheap and what is it used for?
its available naturally and is used to line furnaces
each carbon atom in graphite is covalently bonded to how many other carbon atoms?
3 others-forming layers of hexagons leaving one free electron per carbon atom
how can graphite conduct electricity?
these free electrons migrate along the layers and are free to move and carry charge
what are the covalent bonds like in graphite?
very strong
how are the layers of ions in graphite attracted to eachother?
by weak intermolecular forces
what makes graphite soft and slippery?
the layers can slide over eachother as they are attracted by weak intermolecular forces
the physical properties of graphite?
it can conduct electricity and heat, has a high melting and boiling point and it is soft and slippery and less dense than diamond
what makes graphite a useful material?
the weak intermolecular forces-make if soft and slippery
does fullerene have a large surface area of small surface area?
large surface area
what happens when non-metal atoms share pairs of electrons?
they get a full outer shell
what are simple molecules?
a small group of atoms held together by covalent bonds
when simple molecules boil what breaks?
the weak intermolecular forces
what does electrical conductivity require?
charged particles that can move freely
why do simple molecular substances never conduct electricity?
because the molecules are neutral
c60 fullerene is an electrical…
insulator
