Bonding And Periodicity Flashcards
Describe the structure and bonding in graphite and why the melting point is so high (4)
Layers of carbon atoms
Connected by covalent bonds between the layer
Weak can der waals between the layers
Require a lot of energy to break the strong covalent bonds
Why does iodine have a higher melting point than bromine
Iodine is a larger molecule and has more electrons so it has more and stronger van der waals forces between the molecules
Why does NaI have a lower boiling point than NaBr (1)
Iodide ions are bigger so they are less attracted to the Na+
Why is ice less dense than water
The water molecules in ice are held further apart
How many lone pairs are in a hydroxide ion
3
Why is there no Hudrogen bonding between PH3 molecules
The electronegativity difference between P and H is too small
Why is graphene a good conductor of electricity (2)
Delocalised electrons between the layers
Can conduct electricity
Why do metals hammered into objects with different shapes still have similar strengths
The strong metallic bonds are reformed therefore the bond strength remains the same
What is periodicity
Repeating patterns / trend in physical and chemical properties of elements accross period of periodic table
What 2 deviate from the trend of increasing first ionisation energies in period 3
Aluminium and sulfur
What is the trend in melting points of phosphorus sulfur and chlorine
Sulfur is highest then phosphorus then chlorine
Sulfur is the largest so it has the most electrons and most van der waals
What 4 structures are macromolecules
Diamond
Graphite
Silicon dioxide
And silicon
What are 3 properties of diamond
Very rigid
Each carbon bonded to 4 others
No delocalised electrons so doesn’t conduct electricity
3 properties graphite
Each carbon bonded to 3 carbons
Weak vdw between the layers that can slide over each other (soft / slippery)
Conducts electricity due to delocalised electrons
