UNIT 1 Section 3 - Bonding Flashcards
what does the perfect ionic model include
ions are perfectly spherical and the bonding is only ionic with no covalent character
what are ionic crystals
ginat lattices of ions when ions are arranged in a regular repeating pattern
what is the definition of ionic bonding
the bonding between a metal and non metal resulting in a strong electrostatic attraction between oppositely charged ions in a lattice
what are the properties of ionic compounds
high melting points- strong ele. static att. throguhout giant lattice of + and - ions
conduct electricity when molten or dissolved as ions are free to carry a charge
brittle as when ions are moved near a similar charge they allign and repel
soluble in polar solvents as the polarity can aften pull the ions apart and overcome the elec. attraction
what is the definition of covalent bonding
when 2 atoms nuclei share a pair or or more of valence electrons
what are the properties of giant covalent structures
high melting/ boiling point- multiple strong covalent bonds
rigid- strong covalent bonds
what are giant covalent structures and how can carbon form themm
crystal structures with a huge network of covalently bonded atoms which can be formed due to the fact carbon can make 4 covalent bonds
what is a dative covalent bond
when an electron deficient atom accepts a lone pair of electrons donated from an atom/ion with a lone pair to form a covalent bond
what is the structure/properties of diamond like
-each c is bonded 4 times tetrahedral
-cannot conduct electricity as no charged particle
-high MP due to many strong covalent bonds
what is the structure/properties of silica like
- each Si is bonded to 4 stoms to from lots of covalent bonds
-high MP and BP due to sterong covalent bonds
-doesn’t conduct electricity due to no charged particles
what is the structure/properties of graphite
- each carbon forms 3 covalent bonds forming hexagonal rings of carbon atoms arranged in layers
van der Waals forces of attraction between layers
soft and slippery due to layers
high MP due to strong covalent bonds
conducts electricity as the one electron in the outer shell gets released and is a delocalised electron that can carry a charge
what is the structure/ properties of graphene
single layer
extremely strong due to strong covalent bonds
has delocalised electrons that can carry a charge
what is the definition of metallic bonding
strong electrostatic attraction between delocalsied electrons and layers of positive metal ions
what are the resulting properties of metallic bonding
malleable- layers of positive metals can slide over each other
high BP/MP- strong electrostatic attraction between delocalised electrons adn + metal ions
good conductors of electricity- delocalised electrons can carry charge freely throughout giant metallic structure
what is the bonding in simple molecular compounds and what is the intermolecular force
covalently bonded molecules
multiple molecules held together by weak van der Waals
what are the properties of simple molecular substances like
low BP/MP- weak VDW’s meaning little energy to overcome
poor conductors- no charged particles to carry the charge
gases or liwuids at room temp- weak VDW’s
what is a molecule and what are they held together by
are 2 or more atoms bonded together held together by covalent bonds
what are the 5 common polarised bonds
nitrogen- hydrogen
oxygen- hydrogen
carbon-halogen
carbon-oxygen
hydrogen-halogen
when does hydrogen bonding happen
lone pair of electrons on an O,F,N attract the delta plus of a H bonded to an O,N,F as there is a strong force of attraction between H nucleus and lone pair of electrons on ONF
howo does hydrogen bonding work
a lone pair of the electronegative atom N,O or F is attracted to the slightly positively charged H that is bonded to another electronegative atom in a neighbouring molecule
how does the permanent dipole intermolecular force work
moleucles with permenant dipoles attract other molecules with permanent dipoles
how does the temporary dipole intermolecular force work
movement of electrons can induce a temporary dipole which can induce a temporary dipole in a neighbouring atom so the slightly negative repels the electrons in the neighbouring atom to create a slightly positive charge which attract
what is the definition of electronegativity
the ability of an atom to attract the pair of electrons in a covalent bond
what factors effect electronegativity
atomic radius- the ability of the nueclus to attract e- dcreases as the atomic radius increases
nuclear charge- the bigger the nuclear charge the higher the ability of the nucleus to attract the e-
electron shielding- the more electron shielding the more repulsion of the electrons so less likely to attract them
what does polar mean
an uneven charge distribution due to difference in electronegative
what is the definition of an induced dipole
temporary dipoles are created by the random movement of electrons and this induced a dipole in the neighbouring molecule due to repulsion which then causes attraction between the molecules and therefore Van der Waals
what is a permanent dipole
a significant difference in electronegativity of two atoms causes attraction and attraction in neighbouring molecules
what can multiple polar molecules join together to from
a lattice of molecules
each lone pair decreases the bond angle by roughly how much
2.5
what is the repulsion trend
lone pair-lone pair repels more than bonded-bonded
why are molecules containing polar bonds not always polar overall
if the bonds are symetrical and cancel out the molecule as a whole is non polar
why does water bend towards a charged rod
the water molecule has a - and + side to it so the molecule can turn to attract the water and electrostatic attraction is present
what is simple molecular covalent bonding
strong covalent bonds between atoms and weak van der Waals forces of attraction between molecules
are there any lone electrons in simple covalent bonding
no all of them are involved in bonding
how does the strength of metallic bonds change across the periodic table and why
increases
higher charge on metal ions and therefore more delocalised electrons per ions and therefore stronger electrostatic attraction between them
why is ice less dense than liquid water
in liquid water the hydrogen bonds constantly break and reform with the molecules moving about
hydrogen bonds hold the molecules in fixed positions this makes them slightly further apart than in liquid water
what does the electron pair repulsion thoery state
that electron pair will take up positions as far away from each other as possible to minimise repulsive forces between them
