Bonding and Structure Flashcards
shape and angle for 2 bonding pairs
linear- 180 degrees
shape and angle for 3 bonding pairs
trigonal planar-120 degrees
shape and angle for 4 bonding pairs
tetrahedral- 109.5 degrees
shape and angle for 5 bonding pairs
trigonal bipyramidal- 90 and 120 degrees
shape and angle for 6 bonding pairs
octahedral- 90 degrees
shape and angle for 3 bonding pairs + 1 lone pair
trigonal pyramidal, 107 degrees
shape and angle for 2 bonding pairs + 2 lone pairs
bent, 104.5 degrees
explanation for angles in a molecule
if there any state how many lone pairs there are
if lone pairs are present state that lp-lp repel more the bp-bp
electrons pairs arrange themselves around the central atom to minimise repulsion
what causes London forces?
temporary asymmetrical electron distribution induces a dipole in adjacent molecule
why does Mg have a higher melting point than Na
Mg has more delocalised electrons than Na
Mg2+ has a larger charge than Na+
Mg2+ is smaller than Na+
Mg’s delocalised electrons and cations have a stronger electrostatic attraction
explanation for SHAPE of a molecule
state how many electron pairs there are
why is cyclohexane not soluble in water?
cyclohexane can only form London forces
it wouldn’t be able form hydrogen bonds with water
effect that branching has on a molecules boiling point?
decreases the surface area of contact for London forces to occur so boiling point has decreased
why does water have a higher boiling point that expected?
water can form two hydrogen bonds per molecule because the oxygen has two lone pairs
stronger hydrogen bonding
what effect does hydrogen bonding on density of ice compared to water?
ice has lower density than water
hydrogen bonds holds the molecules further apart
forms a tetrahedral arrangement
physical properties of diamond
each carbon atom forms four covalent bonds (giant covalent structure)
cannot conduct electricity because all electrons are involved in bonding
arrangement and physical properties of graphite
carbon atoms arranged in layers
3 localised electrons and 1 delocalised electron per carbon atom
the delocalised electron is mobile and carries charge throughout the structure
Define ‘electronegativity’
The ability for an atom to attract a pair of electrons in a covalent bond
why are metals malleable?
layers of ions can slide over each
electrons between the layers can prevent repulsion
why are ionic solids brittle?
layers of ions are displaced when bent and the ions of the same charge line up and repel each other
