Properties of Period 3 elements and reactions with water
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What is the main physical trend across Period 3?
Elements change from metals on the left to non - metals on the right across Period 3
Which Period elements are metallic and what are their 3 main properties? S/M/Alm. • shny. whn. frshly. C • gd. cndctrs. E • rct. w/ dlte. acds. - frm. H + slts.
Sodium, magnesium and aluminium • Shiny when freshly cut • Good conductors of electricity • React with dilute acids to form hydrogen and metal salts
What type of element is silicon?
A semi - metal (metalloid)
Which Period 3 elements are typical non - metals and what are their 3 main properties? (Phos/slfr/chlrne/) • electricity conduction? • low M/B point
Phosphorus, sulfur and chlorine • Do not conduct electricity • Low melting and boiling point
What type of element is argon and what are its properties? • inert • montmc. elmnt.
Argon is a noble gas • Chemically unreactive • Exists as separate atoms (monatomic)
Which Period 3 metals/non metals react with cold water? (S/M rct. w/ CW - CL rcts. w/ wtr.)
Metals: Sodium and magnesium react with cold water Non - metals: Chlorine is the only non - metal in Period 3 that reacts with water
Describe the reaction of sodium with cold water (rcts. vigrly. - fzs. rpdly. + frms. bll. flt. wtr.)
Sodium reacts vigorously with cold water, fizzes rapidly and forms a ball to float on water
Products formed when sodium reacts with cold water?
Sodium hydroxide solution and hydrogen gas
Write the balanced symbol equation for sodium reacting with cold water
2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂ (g)
What is approximate pH of the reaction between sodium and water
13
How does magnesium react with cold water at room temperature? (rcts. slwly. w/ CW - frmng. wk. alk. sol. - Mg(OH)₂)
Magnesium reacts very slowly with cold water, forming a weak alkaline solution of magnesium hydroxide
Why is the solution formed from magnesium and water less alkaline than sodium hydroxide (Mg(OH)₂ - spar. sol - fewer OH- rlsd. sol.)
Magnesium hydroxide is only sparingly soluble, so fewer OH- ions are released into solution
Write the balanced equation for magnesium reacting with cold water
Mg (s) + 2H₂O (l) → Mg(OH)₂ (aq) + H₂ (g)
How does magnesium react with steam? (rcts. rpdly. w/ stm. )
Magnesium reacts rapidly with steam when heated
Products formed when magnesium reacts with steam?
Magnesium oxides and hydrogen gas are formed
Write the balanced equation for magnesium reacting with steam
Mg (s) + H₂O (g) → MgO (s) + H₂ (g)
How does chlorine react with water, and what products are formed? (rcts. rvsrble. rctn. - prod. chlrc acd. + HCL)
Chlorine reacts with water in reversible reaction, to produce chloric acid and hydrochloric acid
Write the balanced equation for chlorine reacting with water
Cl₂ (g) + H₂O (l) ⇌ HCl (aq) + HOCl (aq)