15. Periodic Table Flashcards
(45 cards)
What trend is observed for atomic radius across Period 3?
Decreases
Why does atomic radius decrease across Period 3?
Increasing nuclear charge with constant shielding
Why is argon’s atomic radius excluded in comparisons?
Argon is monoatomic with minimal electron cloud overlap
How do anions compare in size to cations?
Anions are larger
Why do cations in Period 3 decrease in ionic radius?
Increasing nuclear charge in isoelectronic ions
Why are anions larger than their parent atoms?
Greater inter-electronic repulsion
What general trend is observed in 1st ionisation energy across Period 3?
Increases
Why does ionisation energy increase across the period?
Increasing nuclear charge with constant shielding
Which element in Period 3 has a lower than expected ionisation energy?
Aluminium
Why is sulfur’s ionisation energy lower than expected?
Electron-electron repulsion in the 3p orbital
What happens to electronegativity across Period 3?
Increases
Why does electronegativity increase across the period?
Increased nuclear charge without increased shielding
Why do metals in Period 3 have high melting points?
Strong metallic bonds
Which element in Period 3 has the highest melting point?
Silicon
Why does Si have the highest melting point?
Giant molecular structure with strong covalent bonds
Which elements in Period 3 conduct electricity?
Na, Mg, Al
Why do metals conduct electricity?
Delocalized electrons act as mobile charge carriers
Which oxides in Period 3 are ionic?
Na2O, MgO, Al2O3
Why does Al2O3 have covalent character?
High charge density of Al3+
What kind of structure does SiO2 have?
Giant molecular structure
What type of bonding is present in P4O10 and SO3?
Covalent
What does Na2O form when it reacts with water?
NaOH
Which oxide in Period 3 is amphoteric?
Al2O3
Why is SiO2 insoluble in water?
Strong covalent bonds
