Period 3 elements and oxides Flashcards
What are the physical trends across period 3?
Na,Mg and Al- metallic
Si- metalloid
P, S & Cl- non-metal
Ar- noble gas
What type of reaction happens to period 3 elements?
Redox reactions
Which period 3 elements react with cold water?
Na, Mg and Cl
How does Na react with cold water?
Na reacts vigorously, fizzing rapidly producing a strongly alkaline solution(13-14)
How does Mg react with cold water?
Mg reacts very slowly producing a weakly alkaline solution(~10)
Why is Na more reactive than Mg?
It takes less energy to lose one electron than to lose two.
How does Mg react with steam?
Faster reaction
What happens when period 3 elements react with oxygen?
They are oxidised to their highest oxidation states (same as their group numbers) except sulfur.
Why is sulfur an exception when it reacts with oxygen?
SO2 is produced which has a +4 oxidation state
High temperature and a catalyst are needed to make SO3 where sulfur has an oxidation state of +6
How does Na react with oxygen?
It burns with a yellow flame
Vigorous
White Na2O is produced
How does Mg react with oxygen?
It burns with a bright white flame
Vigorous
MgO is produced
How does Al react with oxygen?
Slowly (faster if powdered)
How does Si react with oxygen?
Slowly
How does P react with oxygen?
Red phosphorus must be heated before it reacts with oxygen
White phosphorus spontaneously ignites in air. White smoke is given off
(Red and White P are allotropes)
How does S react with oxygen?
Burns steadily with a blue flame
What are allotropes?
Atoms of the same element arranged differently
What is the bonding and structure in Na2O, MgO and Al2O3?
They have giant ionic lattices and therefore high melting points
It is ionic bonding
Why does MgO have a higher melting point than Na2O?
Mg forms 2+ ions, so the bonds are stronger than 1+ Na ions
Why does that Al2O3 have a lower melting point than expected?
Highly charged Al3+ ions distort the oxygen electron cloud making the bonds partially covalent
What is the bonding and structure in SiO2?
It is covalent bonding
It is a macromolecular structure and therefore a high melting point(strong covalent bonds)