[🧪] Periodicity/Period 3 Flashcards
What is the general trend in
melting points in Period 3?
[🧪] Periodicity/Period 3
Across the period, melting point increases up till Si, then decreases after Si
metallic bonding → giant molecular → simple molecular
What is the general trend in Period 3 for
electrical conductivity?
Across the period, electrical conductivity increases from Na to Al, then decreases after Al
What is the general trend in Period 3 for
ionic radius?
Decreases from Na+ to Si4+, then increases significantly to P3-, then decreases from P3- to S2-
Describe the visual observations when
sodium reacts with oxygen
- vigorous reaction
- bright yellow flame
- Na₂O formed (white solid)
Describe what happens when
magnesium reacts with oxygen
- speed: vigorous reaction
- observations: burns with a bright white flame
- product: MgO (white solid)
Describe the visual observations for when
powdered aluminium reacts with oxygen
- fast reaction
- bright white flame
- Al₂O₃ formed (white powder)
Describe the visual observations for when
silicon reacts with oxygen
- speed: slow
- observations: bright white sparks
- product: SiO₂ (white powder)
Conditions for the reaction between aluminium and oxygen
Powdered aluminium
Conditions for the reaction between silicon and oxygen
Powdered silicon and strong heating
Describe what happens when
phosphorus reacts with oxygen
- speed: vigorous reaction
- observations: yellow or white flame
- product: P₄O₁₀ (seen as white clouds)
What is the product of phosphorous reacting with oxygen?
P₄O₁₀
Describe the visual observations for when
sulfur reacts with oxygen
- gentle reaction
- blue flame
Conditions for the reaction between sulfur and oxygen?
Powdered sulfur
Speed of the reaction of sodium/magnesium/aluminium with chlorine gas
Vigorous
Speed of the reaction of silicon/phosphorous with chlorine gas
Slow
Conditions for the reaction between phosphorous and chlorine gas
Excess chlorine
What happens when NaCl and MgCl₂ are put in water
- don’t react
- the polar water molecules are attracted to the ions and break down their giant ionic structures, dissolving them
What happens when Al₂Cl₆ is put in water?
- broken down into Al3+ and Cl- ions, so the solid disappears
- Al3+ becomes hydrated, causing the water molecule bonded to it to lose an H+ ion, giving an acidic solution
- H+ and Cl- ions form HCl, given off as misty white fumes
- temperature increases
Which Period 3 chlorides undergo a complete reaction with water?
SiCl₄ and PCl₅
Describe the visual observations for when
SiCl₄ reacts with water
- HCl given off as white fumes
- SiO₂ formed (white precipitate)
- rapid reaction
Describe the visual observations for when
PCl₅ reacts with water
rapid reaction
How many molecules of HCl are given off when SiCl4 reacts with water?
4
How many molecules of HCl are produced when PCl5 reacts with water?
5
Trend of pH of solution formed when Period 3 chloride interacts with water
Across the period, the pH of the solution formed decreases when Period 3 chlorides interact with water
What happens to the HCl produced by the reaction between PCl₅ and water?
The HCl, along with the H₃PO₄, dissociate in solution
