2. bonding and structure (as) Flashcards
ionic bonding
strong electrostatic attraction between oppositely charged ions
ionic bonding involves
the transfer of electrons from a metallic element to a non metallic element
ionic solids structure
ions in a lattice are arranged in a regular repeating pattern
ionic radius def
measure of the size of an ion
ionic radii increases with
ionic radii decreases with
increasing negative charge
increasing positive charge
negative ions formed by
atoms gaining electrons
isoelectronic ions
ions that have the same electronic configuration
the type of lattice formed depends on
the sizes of positive and negative ions which are arranged in alternating fashion
why are most ionic compounds are solids at room temp
there isn’t enough energy to overcome the strong electrostatic forces of attraction between oppositely charged ions that make up the lattice
ionic compounds require to melt
high temperatures required to make an ionic compound melt or boil
electrical conductivity of ionic compounds
in solid they cannot conduct electricity
but molten or aqueous ions they have ions that can move and carry charge
things that affect the strength of an ionic bond
ionic charge
ionic radii increases
ionic charges affects ionic bond how
greater charge of ion stronger the ionic bond ,, higher mp/bp
ionic radii explain how it affects ionic bond
smaller ions can be packed closer together than larger ions electrostatic attraction gets weaker with distance ,, small, closely packed ions have stronger ionic bonding
what happens to ionic radii down a group
ionic radii increases
what happens when isoelectronic ions ionic radii as atomic number increases
ionic radii decreases
physical properties of ionic compounds
- high mps-
- soluble in water but not in non polar solvents
- don’t conduct electricity when solid
- brittle
migration of ions evidence for charged particles
- copper (II) chromate (VI) solution is green on a piece of filter paper
- cathode- filter paper is blue because copper ions- pos ions
- anode- filter paper is yellow because of chromate ions- neg ions
covalent bonds
strong electrostatic attraction between two positive nuclei and the shared electrons in the bond
bond length
distance between the attractive and repulsive forces that balance each other between two nuclei
relation between bond enthalpy and bond length
the greater the bond enthalpy the shorter the bond
dative covalent bonding
one atom donates both electrons to a bond
structure of diamond and silicon (IV) dioxide
each carbon atom bonded to 4 other and silicon is similar but has oxygen atoms between silicon
properties of giant structure w covalent bonds
high mp
hard
good thermal conductors
insoluble-
can’t conduct electricity-
why can graphite conduct electricity
3 carbon atoms covalently bonded ,, one free electron ,, carry charge
graphene structure
- sheet of graphite
- joined together hexagonal
- one atom thick
- two dimensional
- conducts electricity
- strong
- transparent
- light
metallic bonding
positive metal ions electrostatically attracted to the delocalised negative electrons forming a lattice of closely packed ions in a sea of delocalised electrons
metals structure
- high melting point
- malleable/ ductile
- good thermal conductors-
- good electrical conductors-
- insoluble
what affects metallic bond
- number of electrons
- size of metal ions
- charge of metal ions
electronegativity def
the ability of an atom to attract the bonding electrons in a covalent bond
most electronegative element
fluorine
do ionic compounds have high mp? and why
strong attraction between ions
are ionic compounds soluble and why
soluble in water but not non polar solvents-tells you that particles are charges ions pulled apart by polar molecules like water
do ionic compounds conduct electricity
- don’t conduct electricity when solid- ions not free to move
are ionic compounds brittle and why
yes they are brittle bcs if layers pulled same charged ions could be above each other ,, repulsion would be strong
does giant structure w covalent bond have high mp + explain
require a lot of energy to break bonds
giant structure w covalent bond hard+ explain
strong bonds through lattice
is giant structure w covalent bond good thermal conductors + explain
vibrations travel easily through lattice
are giant structure w covalent bond insoluble + explain
covalent bonds are more attracted to their neighbours in lattice than solvent molecules. don’t have ions bcs insoluble in polar solvents
does giant structure w covalent bond conduct electricity + explain
no charged ions/ free electrons
does metal structure have high melting point + explain
- strong metallic bonds
is metal structure malleable/ ductile + explain
metal ions can slide over each other without disrupting attraction between pos ions + e
is metal structure a good thermal conductors/electrical conductors + explain
delocalised e can pass KE to each other
is metal structure insoluble + explain
strength of metallic bonds