2.4 Properties of Period 3 Elements and their Oxides

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Total cards: 24•Content version: v4•Public deck•Updated: 8/1/2026

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Front (Question)

Appearance and physical properties of sodium?

Back (Answer)

Metallic, shiny, conducts electricity (worst conductor out of the metals)

Front (Question)

Reaction of sodium with water

Back (Answer)

Vigorous reaction, floats on water, fizzes, melts due to -ΔH of the reaction.

Front (Question)

Reaction of sodium with oxygen

Back (Answer)

Bright yellow flame, forms white powder of Na2O

Front (Question)

Appearance and physical properties of magnesium?

Back (Answer)

Metallic, shiny, conducts electricity (between Na and Al in terms of how well it does).

Front (Question)

Reaction of Mg in cold water

Back (Answer)

Very slow reaction. pH = 10 as Mg(OH)2 is sparingly soluble

Front (Question)

Reaction of Mg with steam

Back (Answer)

Much faster

Front (Question)

Reaction of Mg with Oxygen

Back (Answer)

Bright white flame, forms white powder of MgO

Front (Question)

Appearance and physical properties of aluminium?

Back (Answer)

Metallic, shiny, best conductor of electricity in period 3

Front (Question)

Reaction of Al with water

Back (Answer)

None

#10

Front (Question)

Reaction of Al with Oxygen

Back (Answer)

Heat and lower into jar of O2 → bright flame, forms white powder.

#11

Front (Question)

Why is aluminium considered unreactive even though the metal itself is reactive?

Back (Answer)

Covered by Al2O3 from where oxygen has oxidised the surface of the Al. Al2O3 is unreactive. Makes it useful for saucepans, window frames etc. If Al2O3 is scratched off, Al reacts rapidly with air to form a new coat.

#12

Front (Question)

Appearance and physical properties of silicon?

Back (Answer)

Semimetal (metalloid), semiconductor (conducts electricity to an extent and in certain conditions)

#13

Front (Question)

Reaction of silicon with oxygen

Back (Answer)

White powder produced when strongly heated

#14

Front (Question)

Appearance and physical properties of phosphorus?

Back (Answer)

Non-metal, low m.p. And b.p., does not conduct electricity. Red Phosphorus as a crystal structure White Phosphorus as P4

#15

Front (Question)

Reaction of phosphorus in excess oxygen

Back (Answer)

Red P needs to be heated significantly first, white P ignites spontaneously in air Phosphorus pentoxide (white crystalline solid) formed

#16

Front (Question)

Reaction of P in limited oxygen

Back (Answer)

Incomplete combustion: colourless liquid phosphorus trioxide is formed.

#17

Front (Question)

Appearance and physical properties of sulfur?

Back (Answer)

Non-metal, low mp and bp, does not conduct electricity.

#18

Front (Question)

Reaction of sulfur with O2

Back (Answer)

Need to heat and lower into a jar of oxygen. Colourless gas sulfur dioxide formed. Some SO3 also formed.

#19

Front (Question)

What is the trend in melting points for period 3 oxides (state highest and lowest and why and draw graph)?

Back (Answer)

Highest is MgO, lowest is SO2 ; increases along group for metals for Na2O and MgO due to stronger ionic bonding, but Al2O3 is lower due to the covalent character of the bonding. Decreases with size for simple molecular molecules.

#20

Front (Question)

Which period 3 oxides are basic?

Back (Answer)

Na2O and MgO

#21

Front (Question)

Reaction of Na oxide with water

Back (Answer)

Na2O + H2O → 2Na+ + 2OH- ; pH = 14

#22

Front (Question)

Reaction of Mg oxide with water

Back (Answer)

MgO + H2O → Mg2+ + 2OH- ⇌ Mg(OH)2 ; pH = 9-10 as Mg(OH)2 is sparingly soluble

#23

Front (Question)

What are the products if Na2O and MgO are reacted with acid?

Back (Answer)

Salt and water

#24

Front (Question)

Is aluminium oxide basic or acidic?

Back (Answer)

It is amphoteric; can act as either an acid or a base