Period 3 - Elements And Oxidies Flashcards
What are the metals in period 3 that react with cold water?
- Sodium
- Magnesium
Aluminium reacts with…
Steam
What happens when sodium reacts with cold water
- Floats, fizzes, moves across the surface, melts into a ball
- pH 13-15
2Na + 2H2O -> 2NaOH + H2
What happens when magnesium reacts with cold water?
- slower reaction, bubbles cling to Mg, dissolves after a few days
- pH: 10
Mg + 2H2O -> Mg(OH)2 + H2
Why is Mg(OH)2 less alkali than NaOH?
Mg(OH)2 is sparingly soluble so less [OH-]
How does Mg react with steam
- bright white flame
- white solid produced
How does aluminium react with steam
- bright white flame, white solid produced
2Al + 3H2O -> Al2O3 + 3H2
How are the oxides of Period 3 prepared?
- By the direct reaction with oxygen
- all reactions are exothermic
What is the reaction of Na with O2
- orange flame white smoke
4Na + O2 -> 2Na2O
What is the reaction for the addition of water to sodium oxide
Na2O + H2O -> 2NaOH
What is the reaction of Mg with oxygen?
- bright white flame, white solid produced
2Mg + O2 -> 2MgO
What is the reaction of MgO with water?
MgO + H2O -> Mg(OH)2
PH 9-10
What is the reaction of aluminium and oxygen?
- Bright white flame, white solid produced
4Al + 3O2 -> 2Al2O3
What is the reaction between silicon and oxygen?
Si + O2 -> SiO2
What is the reaction of phosphorus with oxygen?
- bright yellow flame, white smoke
- P4 + 5O2 -> P4O10
What is the reaction between phosphorus (V) oxide and water?
P4O10 + 6H2O -> 4H3PO4
PH 1-2
What is the reaction of sulfur with oxygen?
- Blue flame and misty fumes
- S + O2 -> SO2
- S + 3/2 O2 -> SO3
What are the acids formed from sulfur dioxide/trioxide?
H2SO3 + H2SO4
Which sulfuric acid is more acidic
H2SO4
Why does MgO have a higher boiling point than Na2O
Giant ionic
- Mg2+ is more charge dense
Why does Al2O3 have a lower melting point than MgO
As it has covalent character
- weakens the ionic bond
Why does SiO2 have a high melting point
Giant covalent structure
Why does P4O10, SO3 and SO2 have low melting points
Simple molecular
- strong covalent bonds between atoms
- weak VDW between molecules
- bigger the molecule more e-
H3PO4, H2SO3 and H2SO4 are…
Oxoacids
What is formed when an oxoacid dissociates
Oxoanions
What is the shape of the oxoanion for phosphoric acid?
- tetrahedral 109.5
What is the shape for the oxoanion of H2SO3
Trigonal pyramidal 107
What is the shape of the oxoanion for H2SO4
Tetrahedral 109.5
Na2O and MgO are basic/acidic oxides
Basic
Al2O3 is a …………. Oxide
Amphoteric
Why does Al2O3 have acidic and basic properties
The Al-O bond has covalent character
How does Al2O3 react with a base?
It reacts with hot concentrated sodium hydroxide to make sodium aluminate
Al2O3 + 2NaOH + 3H2O -> 2NaAl(OH)4
Describe the properties of the oxides: SiO2, P4O10, SO2 and SO3
Acidic
What is the equation for the reaction between SiO2 and NaOH?
SiO2 + 2NaOH -> Na2SiO3 + H2O
Sodium silicate
What is the reaction between P4O10 and NaOH
P4O10 + 12 NaOH -> 4Na3PO4 + 6H2O
Sodium phosphate
What is the reaction between SO2/SO3 and NaOH
SO2/3 + 2NaOH -> Na2SO3/4 + H2O
