Periodicity
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What is periodicity
Repeating trends of physical/ chemical properties
How are elements arranged in the periodic table
By increasing atomic number
What is the trend of atomic radius down a group and why
Atomic radius increases down a group as the number of shells increases, shielding increases, the outer electron is further away from the nucleus and there’s a weaker attraction between nucleus and hte outer electron
What is the trend of atomic radius across a period
Atomic radius decreases across period. Number of proton increases, Shielding stays the same, there’s a stronger attraction of nucleus to outer electron
What is ionisation energies
Energy required to remove 1 mol of electrons from 1 mol of gaseous atoms
Equation for ionisation energy
X(g) -> X+(g) + e-
Trend for IE down a group
IE decreases down a group as electron is removed from a higher principle energy level, the electron is further away from the nucleus, there are more shielding, so weaker attraction between nucleus and outer electron
Trend of IE across a period
IE increases across a period as the number of proton increases, the shielding is constant, there is stronger attraction between the nucleus and outer electron
Trend of IE of group 3
IE decreases as electron is removed from a higher energy p sub level, there’s weaker attraction between nucleus and the outer electron
Trend of IE of group 6
IE decreases as there is a pair of electron in the p-orbital, there is extra repulsion so less energy is required to remove th electron
Successive ionisation energy trend
Succession IE increases, it’s more difficult to remove an electron from a more positive ion, ionic radius decreases, nuclear attraction on the outer electron increases
Metallic bonding
Strong electrostatic attraction between positive ions and delocalised electrons
What’s the structure of metallic bonding
Giant metalllic lattice
3 factors of metallic bonds
• ionic charge ( higher charge) • number of delocalised electrons (more electrons) • ionic radius ( smaller radius)
property of metals
• High melting boiling point • Good conductor of electricity and heat • Malleable and ductile
Why is metal good conductor of electricity and heat
As metal have delocalised electrons that are free to move and flow
Why does metal have high melting and boiling point
As strong electrostatic attraction between positive ions and delocalised electrons require lots of energy to break
Why are metals malleable and ductile
As layers of ions can slide over each other
5 Giant Covalent
• Diamond • Graphene • Graphite • Silicon • Silicon Dioxide
Which Giant covalent can conduct electricity and why
Graphene and Graphite can conduct electricity as they have delocalised electrons that are free to move
Why does all Giant covalents have high melting boiling points ?
As strong covalent bonds between the ATOMS require lots of energy to break
What are the 4 points when comparing boiling and melting points
Bonding Structure IMF Strongest IMF