Periodicity Flashcards
How is the periodic table arranged?
By atomic number in periods and groups
What do all elements have the same in periodsn and groups ?
Elements in the same periods have the same number of shells and elements in the same group have the same number of outer shell electrons
Where is the s block on the periodic table?
Group 1 and 2
Where is the d block on the periodic table?
Scandium to zinc (excluding lanthanides and actinides)
Where is the p block on the periodic table?
Boron to neon (he and h are in s block)
Where is the f block ?
Lanthanides and actinides
What is the trend of atomic radius across a period eg Na to Ar
It decreases as the number of protons increases the positive charge of the nucleus increases so the electrons are pulled closer to the nucleus making it smaller
What do the gained electrons have to do with decreasing radii?
They dont because they’re outer shell so they dont really provide ant extra shielding effect
Why is the trend in melting points for period three not obvious
From na to Si it steadily increases and from Si to ar it steadily decreases. This is as sodium magn and al are metals, their melting points increase across the period because of the metal-metal bonds getting stronger meaning the metal has an increasing positive charge and an increased number of delocalised e with a decreasing radius,
Why from na to al does the melting point increase
This is as sodium magn and al are metals, their melting points increase across the period because of the metal-metal bonds getting stronger meaning the metal has an increasing positive charge and an increased number of delocalised e with a decreasing radius,
What is silicon?
Macro molecular with a tetrahedral structure with strong covalent bonds linking its atoms together. A lot of energy is required to break these bonds so Si has a high melting point
Why does the melting point decrease after Si ?
P, S and Cl are all molecular substances, their melting points depend on the strength of their van der waals forces which are weak and easy to overcome thus the low melting point. More atoms in a molecule means stronger VDW
What is the first ionisation energy (and trend in p3)
Energy required to remove 1 e from each atom in one mole of gaseous atoms to form 1 mole of 1+ gaseous ions. Trend in p3 is that because of the increasing attraction between the outer shell electrons and the nucleus (proton number inc) there is an increasing first ionisation energy across a period
