Periodicity Flashcards
What does periodicity mean?
Patterns or trends that show in the periodic table (groups or periods)
Trend of First Ionisation energy as you go down the group..?
Decreases because atomic radius increases which means shielding increases which means less nuclear attraction of outer electron.
Trend of first ionisation energy as you go across the period?
Ionisation energy increases because atomic radius doesn’t change which means shielding is constant. However number of protons increases so there is a stronger nuclear attraction of outer electron.
What does first ionisation energy mean
The energy required to remove 1 mol of electrons from 1 mol of gaseous atoms
Eg
Mg—> Mg+ + e-
What are the deviations across periods of ionisation energy
From group 2 to 3 ionisation energy decreases because electron is removed at a higher energy P sub level so weak attraction between nucleus and outer electron
Group 5 to 6 ionisation energy decreases because there is a pair of electrons in p orbital in 6 so extra repulsion = less energy required to remove electron
Why will successive ionisation energy’s always increase
- the positive charge on ion increases
- ionic radius decreases
- nuclear attraction on outer electron decreases
How do we work out the group number from successive ionisation energy table
The big jump in ionisation energy (it’s the number that the big jump starts from )
What is metallic bonding
Strong electrostatic attraction between positive ions and delocalised electrons
What factors affect strength of metallic bond
Ionic charge
Number of delocalised electrons( more equals strong )
Atomic radius (small equals stronger )
Why do metals have a high boiling melting point
Strong attraction between positive ions and delocalised electrons
Why are metals good conductors of electricity
Delocalised electrons are Free to move and flow so can conduct electricity
How to draw diagram of metallic bonding
Name 4 giant covalent structures
Diamond Graphite Graphene silicon
Explain melting/ boiling points across period 3
Na —> Al is metallic bonding (increases as charge increases size decreases )
Si is a giant covalent structure so boiling / melting point increases massively as strong covalent bonds
P—> Ar are simple molecular structures that have London forces
S8 is most London forces so highest melting / boiling point then P then Cl then Ar
How would you compare melting / boiling points of substances
Give structure type , type of attraction being broken and relative strength, compare melting points
