Properties Of Period 3 Elements And Their Oxides Flashcards

1
Q

What kind of reactions do period 3 elements under go?

A

All under go redox reactions except argon (noble gas)

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2
Q

What happens when sodium reacts with water?

A

Reacts spontaneously
2Na + H2O ——> 2NaOH + H2

Reaction is very fast

The sodium melts due to the heat released and effervescence that is formed from the hydrogen released

Forms a strong alkali of NaOH

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3
Q

What happens when magnesium is reacted with water?

A

Spontaneous reaction

Mg + 2H2O ——> Mg(OH)2 + H2

Reacts very slowly forming only a few bubbles of hydrogen gas over a few days

However magnesium reacts quickly with steam producing magnesium oxide instead (MgO)

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4
Q

What happens when a period 3 element reacts with oxygen?

A

Forms an oxide (except argon)

Happens when reacted with oxygen and heated

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5
Q

What are the oxides formed and the observations made with period 3 elements?

A

Sodium:
NaO2(s)
Yellow flame/ white solid formed

Magnesium:
MgO
Bright white flame / white powder

Aluminium:
Al2O3
Burns brightly / white solid forms

Silicon:
SiO2
Quartz (silicon dioxide)

Phosphorous:
P4O10 (excess O2) / P2O3 ( limited O2)
Red phosphorus must be heated/ white ignites spontaneously

Sulphur:
SO2 / SO3
Blue flame

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6
Q

What is the bonding like in the period 3 oxides?

A

Na2O ——> Al2O3

Ionic bonding and giant ionic structures

SiO2 covalent bonding and s giant covalent structure

P4O10 ——> SO3

Covalent bonding and molecular structure

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7
Q

What is the trend in bonding across the period 3?

A

Changes from purely ionic to purely covalent

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8
Q

What is the trend in melting points for period 3 elements?

A

Ionic structure have highest melting points

But Al2O3 has a high degree of covalent and therefore has a Lower melting point or other ionic elements

Molecular structures have a decreasing trend as the size and strength of van der waals decreases

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9
Q

What happens when magnesium and sodium oxide react with water?

A

MgO and Na2O are almost completely ionic and so hydration reactions occur.

They form basic solutions which react with acids

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10
Q

What happens when aluminium and silicon oxide react with water?

A

Aluminium oxide and silicon oxide are insoluble and hence do not react with water

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11
Q

What happens when the non metal oxides of period 3 react with water?

A

Forms acidic solutions which react with bases

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12
Q

What happens when aluminium oxide is added to an acid or a base?

A

It will react with both as aluminium oxide is amphoteric and so can act as an acid or base

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13
Q

Why is silicon oxide an acidic oxide? explain using an equation.

A

Non metal oxide and hence forms acidic solutions which react with bases.

SiO2 + 2NaOH —-> SiNa2O3 + H2O

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14
Q

why is the melting point of sulphur oxide lower than phosphorous oxide?

A

SO2 is a smaller molecule and hence has a lower Mr and surface area so the molecule is less polarisable.

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15
Q

Explain why common oxides of Aluminium are insoluble in water?

A

Aluminium oxide is ionic, and therefore has a high lattice enthalpy of dissociation. the enthalpies of hydration do not compensate and hence mean aluminium oxide is insoluble.

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