22 periodicity 2
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what is the trend in nuclear charge across p3?
increase
what is the trend in shielding across period 3?
same amount of shielding
what is the trend in atomic radius across period 3?
decreases across period 3
why does atomic radius decrease across period 3?
increase in nuclear charge same shielding electron shells held closer to the nucleus
does electronegativity increase or decrease across period 3?
increase
why does electronegativity increase across period 3?
increase in nuclear charge same shielding elements increasingly capable of taking electron density from covalent bond
does 1st ionisation energy increase or decrease across period 3?
electron held more tightly and require more energy to be removed
what are 2 exceptions in physical properties across period 3?
Al has lower 1st ionisation energy than Mg S has lower 1st ionisation energy than P
why does Al have a lower first IE than Mg?
Mg has 3s e- removed Al has 3p e- removed 3p higher energy than 3s
why does S have a lower 1st IE than P?
P has 2p e- removed which are unpaired S has 3p e- removed which are paired electron pair repulsion
across period 3, which 2 elements does the melting point increase between?
Na and Al
why does the melting point increase from Na to Al?
nuclear charge increases atomic radius decreases increase in strength of attraction between metal ions and delocalised electrons
which period 3 element has the highest melting point?
silicon
why does silicon have the highest melting point?
macro molecular structure lots of STRONG covalent bonds
what structure and intermolecular forces do the non metals in period 3 have? (S8, P4 and Cl2)
simple molecular van de waals
what differs the strength of the van de waals forces in the non metals in period 3?
the size of the atoms
which non metal in period 3 has the weakest van de waals forces and why?
argon is single atoms
which element across period 3 has the highest boiling point?
aluminium
why does Al have the highest boiling point?
liquid Al has strong electrostatic attraction between delocalised electrons and metal ions so require large amount of energy to boil
write the equation for sodium reacting with water
2Na (s) + 2H2O (l) -> 2NaOH (aq) + H2 (g)
describe the reaction of sodium with cold water
vigorous fizzes rapidly and melts strong alkaline solution formed
write the equation for magnesium reacting with water
Mg (s) + 2H2O (l) -> Mg(OH)2 (aq) + H2 (g)
describe the reaction of magnesium with water
slow room temp few bubbles of gas forms a weak alkali
write the equation for magnesium reacting with steam
Mg (s) + H2O (g) -> MgO (s) + H2 (g)