3.1.3 bonding Flashcards
define ionic bonding
electrostatic attraction between oppositely charged ions in a lattice
define covalent bonding
a single covalent bond contains a shared pair of electrons
what is a dative bond?
a covalent bond that contains a shared pair of electrons with both electrons supplied by one atom
define metallic bonding
attraction between delocalised electrons and positive ions arranged in a lattice
what are the four crystal structures?
ionic
metallic
macromolecular
molecular
can metallic substances conduct electricity and why?
yes they can conduct electricity.
there are delocalised electrons that are free to move
define molecular
isolated molecules containing covalent bonds
in terms of lone pairs and bonding pairs what is the strength of repulsion?
repel the least : bonding pair - bonding pair
repel the most : lone pair - lone pair
how do you work out the shape of a molecule?
- find the group number of the central atom
- count how many electrons are involved in bonding
- count how many electrons are left over
what is the name of the shape with 2 bonding pairs and 0 lone pairs?
linear 180°
what is the name of the shape with 3 bonding pairs and 0 lone pairs?
trigonal planar 120°
what is the name of the shape with 3 bonding pairs and 0 lone pairs?
trigonal planar 120°
what is the name of the shape with 2 bonding pairs and 1 lone pair?
bent ( v shape ) angle less than 120°
what is the name of the shape with 4 bonding pairs and 0 lone pairs?
tetrahedral 109.5°
what is the name of the shape with 3 bonding pairs and 1 lone pair?
trigonal pyramidal 107°
what is the name of the shape with 2 bonding pairs and 2 lone pairs?
bent ( v shape ) 104.5°
what is the name of the shape with 5 bonding pairs and 0 lone pairs?
trigonal bipyramidal 90° and 120°
what is the name of the shape with 4 bonding pairs and 1 lone pairs?
see saw less than 120° less than 90°
what is the name of the shape with 3 bonding pairs and. 2 lone pairs?
T- Shape
less than 120°
what is the name of the shape with 6 bonding pairs and 0 lone pairs?
octahedral 90°
what is the name of the shape with 5 bonding pairs and 1 lone pair?
square pyramid less than 90°
what is the name of the shape with 4 bonding pairs and 2 lone pairs?
square planar 90°
define electronegativity
the power of an atom to attract a shared pair of electrons in a covalent bond
what are the trends in electronegativity?
increases across a period
decreases down a group
explain how electronegativity increases across a period
- shielding effect is constant
- nuclear charge increases
- atomic radius decreases
- attraction between nucleus and shared pair of electrons increases
what makes a bond polar?
when 2 atoms with different electronegativities covalently bond, one atom will attract the shared pair more strongly leading to unequal distribution of the shared pair
what are the 3 types of intermolecular forces?
van der waals
permanent dipole dipole
hydrogen
what are the factors that affect strength of van der waals?
- size of molecule
- points of contact between molecules
how does the size of the molecule affect strength of van der waals?
the bigger the molecule the more electrons it contains and the greater the charge of the imbalance of the temporary dipole. This causes stronger van der waals between forces
how do points of contact affect the strength of van der waals?
straight chained organic molecules can pack closer together than branched molecules leading to more points of contact and stronger van der waals forces
what elements exhibit hydrogen bonding?
oxygen
nitrogen
fluorine
what are properties that arise due to hydrogen bonding?
ice has a lower density than water
