bonding and structure Flashcards
what is the definition of a covalent bond?
the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
what is a valence electron?
an electron on the outer shell
what is a dative covalent bond?
a dative bond is a covalent bond where only one of the bonded atoms donates both electrons being shared
what does a stick in a displayed formula represent?
a covalent bond
how many degreees does a lone pair change the bond angle by?
2.5°
4 bonding pairs and no lone pairs?
tetrahedral
bond angles of 109.5°
3 bonding pairs and 1 lone pair?
pyramidal
bond angles of 107°
2 bonding pairs and 2 lone pairs?
v-shaped
104.5°
3 bonding pairs?
trigonal planar
120°
2 bonding pairs?
linear
180°
6 bonding pairs?
octahedral
90°
what are the election repulsion rules?
lone pairs repel more than bonded pairs
what are the election repulsion rules?
lone pairs repel more than bonded pairs
give the order of strength of intermolecular forces
hydrogen bonding > permanent dipole - dipole > induced dipole-dipole
why does an induced dipole-dipole interaction increase in strength?
more electrons/larger molecule size or less branched carbon chains
what is electronegativity?
the ability of an atom to attract the bonding elections in a covalent bond
define a polarbond
the convent bond between atoms with different electronegativity
define a hydrogen bond
the intermolecular force between the lone pair of a N, O or F of an NH, OH or FH with the H atom of NH, OH or FH in a neighbouring molecule
2 bonding pairs and 1 lone pair?
v-shaped
117.5
define a polar molecule
an unsymmetrical molecule whose dipoles don’t cancel out
what are 2 anomalous properties of water?
- a higher than expected melting and boiling point
- solid water is less dense than liquid water
why is solid water less dense than liquid water?
hydrogen bonding holds water molecules in an open lattice
why does water have a higher than expected boiling point?
strong hydrogen bonding requires a lot of energy to break the intermolecular forves
what is ionic bonding?
the strong electrostatic attraction between oppositely charged ions
why do solid ionic substances not conduct?
the ions are fixed in a lattice and cannot move
how do aqueous and molten ionic substances conduct electricity?
the ions are free to move
what is metallic bonding?
the strong electrostatic attraction between positive ions and delocalised electrons
how do metals conduct electricity?
delocalised electrons can move and conduct electricity
