Bonding Flashcards
2 main types of bonding in compounds
Ionic
Covalent
sulfate ion
SO4^2-
hydroxide ion
OH-
nitrate ion
NO3- (3 IS below)
carbonate ion
CO3 ^2-
ammonium ion
NH4^+
what struc does sodium chloride have
giant ionic lattice
Sodium azide has a high melting point.
Predict the type of bonding in a crystal of sodium azide.
Suggest why its melting point is high.
Ionic
Oppositely charged ions / Na+
and N3 ions
Strong attraction between (oppositely charged) ions / lots of energy needed to
overcome (strong) attractions (between ions) - mark scheme ans
3 features of ionic compounds
1) conduct electrivcity when molten or dissolved - free moving ions that can carry charge
2) ionic compound have high melting points - strong electrostatic attraction bet oppositely charged ions that take alot of energy to overcome
3)ionic compounds tend to dissolve in water - water mol are polar
charged parts pull ions away from lattice
what is covalent bonding
atoms have a shared pair of electrons
what struc has huge network of covalently bonded atoms
giant covalent stuc
macromolecular struc
What is a dative covalent bond?
2 electrons are donated from one atom to another / a lone pair of electrons rather than one from each
2 types of covalent structures
Simple molecular I simple covalent
Macro molecular/giant covalent structures
Examples of simple covalent
Co2 Ch4 Cl2
What is broken when boiling covalent structures
IMF’s not the strong covalent bonds
Examples of giant covalent struc
Diamond, graphite, silicon dioxide
Describe diamonds structure and its properties
Each carbon atoms makes 4 bonds sono free electrons to form used of delocalised electrons to carry charge or conduct electricity thus diamond cannot conduct.
Diamond is hard with a high melting point due to strong covalent bands that take a lot of energy to break
Diamond is insoluble in water
Describe graphite structure and its properties
Giant covalent structure
Can conduct electricity as each carbon atom makes 3 bonds so there is one free delocalised electron per carbon atom forming sea of delocalised elections that can more throughout structure and conduct electricity.
Graphite is soft BCD weak IMF’s I vow between layers d’atoms allowing them to slide over eachother
Has high melting point due to strong covalent bands within mol
Where are covalent bands and imfs found
Covalent - within
IMF’s found between
What is metallic banding ?
Lattice of positive ions surrounded by sea of delocalised_ electrons
There are electrostatic attractions
Properties of metals
Good conductors due to sea of delocalised electrons
High melting and boiling point do to strong bands due to strong attraction
Properties of metals going down a group
Usually looking @ groups 123 - all ions have same charge so this factor not important instead looking at increasing atomic radius so delocalised e-further away from metalions so weaker attraction = weaker metallic bond and so lower boiling point
Properties of metals across a period
Increase in melting point due to increasing charge so stronger attraction between the positive ions and e-so stronger metallic bonds so higher melting point
Why does boron trichlovide have tribunal planar shape?
3 bonds that repel equally to get as for away from eachother as possible lo minimise repulsion.
2BP?
Linear 180°
3BP
trigonal planar 120°
4 bp
Tetrahedral 109.5°
2 bp +2LP
Bent/v -shaped 104. 5°
3BP + one lp
Trigonal pyramidal 107.5°
5 bp
Tribunal bipyramidal 120° + 90°
6 bp
Octahedral 90°
4BP+2LP
Square planar 90°
4BP and one lone pair
See- saw 102° +87°
3 bp t2LP
T-shaped 88°
How to find shape of mol
Determine group no of central. Add one to it for each band it makes. Add one for each negative charge and subtract are for each positive charge. Men divide by 2 to give you number of banding pairs.
Order of now much lone pairs t banding pairs repel
Lone pair 2x) then /lp + 1BP then 2 bp
Define electronegativty
Power of an atom to attract banding pair A electrons in covalent bond
How is polar band formed in h-cl band
Chlorine is mare electronic so attracts banding pair of electrons more strongly giving it a deltanegative charge whilst hydrogen has delta positive. Creates a dipole.
When can something with dipole not be polar
Dipoles cancel out due to symmetrical bonds
3 things that determine it polar on non polar.
If it has delta neg t pos charge = polar
Lone pair = polar
all same atom on outside than nan polar
3 types of intermole ocular forces from highest to lowest strength
Hydrogen bonding
Dipole-dipole interactions (permanent)
Van her walls
Describe vdw
All mol have this IMF
E more within e-cloud e same point there will be more e-on one side than the other creating , induced temporary dipole
Dipole influences another nearby mol inducing a dipole in that
Dipoles only temporary bc e are constantly moving
What molecules * only * contain van her Walls
Non polar
Boiling points and van den walls
Increaesd molecular weight = increased e = stronger V
Van her walls in hydrocarbons
1) chain length increase means more e- so stronger van so higher bp
2) branching of 2 alkanes with same molecular weight, branching decreases chairs length so lower electron su weaker van per Walls so less ar surface areal points of contact
Describe permanent dipole
Eg band h-cl
Large difference in electronegativity
Hydrogen banding occurs between hydrogen and…
Nitrogen, oxygen and fluorine
Solubility of non polar and polar mo)
Polar mol dissolve in polar solvents and non polar md dissolve in non polar solvents
Bc mol dissolved has to form intermolecular forces with solvent, if these stranger than forces broken it will be dissolved su
A mol can dissolve in water it…
It is able to form hydrogen bonds with it.
