Bonding & Properties Flashcards
what is ionic bonding
the strong electrostatic forces of attraction between oppositely charged ions held in a lattice
why do ionic substances have high mp and bp
b/c it takes a lot of energy to break the strong electrostatic attraction between the ions
why do ionic compounds conduct electricity
when molten/dissolved ions are free to move and carry charge
what is simple molecular covalent bonding
strong covalent bonds between atoms, weak van der Waals forces of attraction between molecules
are there any lone pairs of electrons in simple covalent bonding
no
why cant simple molecular covalent molecules conduct electricity
no free electrons to carry charge
why do simple molecular substances have LOW mp and bp
weak van der Waals forces of attraction are easy to overcome
what is macromolecular covalent bonding
lattice of many atoms held together by strong covalent bonds
why do substances w macromolecular covalent bonds have HIGH mp and bp
it takes a lot of energy to overcome many strong covalent bonds
describe the structure of graphite
- macromolecular covalent
- each C atom bonded to 3 others
- in layers
- weak van der Waals forces between layers so layers can slide over eachother = soft + slippery
- one e- from each C is delocalised and can carry charge = can conduct electricity
describe metallic bonding
lattice of positive metal ions strongly attracted to a sea of delocalised e-
malleable - layers can slide over eachother
do metallic compounds have high or low mp and bp and why?
high
strong forces of attraction between +tive metal ions and -tive delocalised e-
why can metallic compounds conduct electricity
delocalised e- can move throughout the metal to carry charge
how does the strength of metallic bonds change across the periodic table? Why?
Increases across table
b/c higher charge on metal ions
more delocalised e- per ion
stronger force of attraction between them
what is a dative covalent bond?
is a covalent bond in which both electrons come from the same atom
