5.3 what are the properties of covalent substances Flashcards
structural properties of simple covalent molecules
held together by strong covalent bonds but weak intermolecular forces of attraction
melting and boiling point of simple covalent molecules
low melting and boiling points
why do simple covalent molecules have low melting and boiling points
the weak intermolecular forces of attraction between molecules are easily overcome with a small amount of energy
what do simple covalent molecules exist as at room temperature
mostly as liquids or gases
solubility of simple covalent substances
most are insoluble in water and soluble in organic substances
electrical conductivity of simple covalent substances
since they typically exist as neutral molecules, they do not have any mobile charge carriers to conduct electricity
however, some simple covalent substances disassociate in water resulting in a solution that can conduct electricity
example of giant covalent structures
diamond and graphite
giant covalent molecules are almost always in the __ state
solid
why are giant covalent molecules almost always in the solid state
because they consist of many atoms that are all connected to one another by strong covalent bonds (which are very different from simple covalent molecules that have wear intermolecular forces of attraction)
diamond and graphites are __ or carbon
allotropes
as they are different forms of the same element with different structured arrangement of atoms
allotrope
different forms of the same element with different structural arrangements of atoms
structural properties of giant covalent structures
have numerous bonds holding many atoms together, making them very rigid and able to withstand large forces
melting and boiling points of giant covalent structures
very resistant to heat due to the large number of bonds in their network. large amount of energy is required to break the strong covalent bonds
what stare are
what state are giant covalent structures in at room temperature
solid
solubility of giant covalent molecules
insoluble in water and in organic solvents
electrical conductivity in giant covalent structures
giant covalent structures with no mobile electrons like diamond and silicon dioxide do not conduct electricity
electrical conductivity in graphite
since each carbon atom is bonded to 3 other carbon atoms, this leaves 1 unbounded electron per carbon atom which is free and mobile to conduct electricity
molecular structure of diamond and silicon dioxide
three dimensional networks
hardness of diamond and silicon dioxide
very hard throughout
melting point of diamond and silicon dioxide
high
solubility of diamond and silicon dioxide
insoluble in water and organic solvents
are diamond and silicon dioxide electrical conductivity
insulator
molecular structure of graphite
two dimensional layers (strong covalent bonds between carbon atoms but weak intermolecular forces if attraction between the layers of carbon atoms)
