Periodicity Flashcards
What is periodicity
The repeating pattern of physical/chemical properties young across the period
What are the 4 blocks
S. P, D, f
What is the block of an element based of
Proton number
Going down block, reactivity
Increases
Explain atomic radius across a period
Decrease because there is an increased number of protons which creates a more positive charge atrachon for electrons. Shielding
Explain atomic radius down a group
Increases, outer electron further
Ionisation energy across a period
There is a general increase in ionisation across a period because of the increasing number of protons as the electrons are being added to the same shell
What are the two deviations for period 3 in ionisation energy
Magnesium and aluminium
Magnesium has its outer electrons in the 3S subshell whereas aluminium has it in the 3p subshell, this is easier to remove as it is higher in energy
Phosphorus and sulphur
Sulphur outer electron is paired up with another electron in the 3p orbital which has a slight proportion making it easier to remove
What is is the general trend in melting and boiling points for sodium, magnesium and aluminium
It gets more stronger due to the metallic bonding. As the ionic charge increases more electrons, join the delocalised of electrons which requires higher energy to break bonds
Explain the melting point for silicon
It is a macromolecular structure which which has strong covalent bonds which requires high energies to break therefore having a high melting and boiling point
Explain the melting and boiling points of chlorine sulphur and phosphorus
They are simple molecular structures with weak VDW forces between the molecules so less energy is required to break them therefore they have low melting points and boiling points
Why does sulphur have a higher melting point then phosphorus?
Because it has more electrons, so it has stronger VDW forces between them
Why has argon got a low melting and boiling point?
It is a monatomic ion which has weak VDW forces between atoms
Explain the general trend in melting and boiling points across period three elements
From sodium to silicon does a general increase sodium to aluminium increases due to the metallic bonding silicone has a highest melting and boiling point in all of period three
This decreases between phosphorus to argon. Sofa has a higher melting and boiling point then phosphorus due to the more electrons and stronger forces but this decreases from sulphur to chlorine and argon has the lowest melting and boiling point in period three
Explain the melting and boiling point across period two
Lithium to beryllium have metallic bonding therefore having a high melting point boron and carbon have a macro molecular structure with strong covalent bond therefore have a high melting point nitrogen and oxygen are molecular and gases so they have a low melting points due to this morning feed vow forces. Neon is a monatomic gas so it has a low melting point.
