Periodic table Flashcards
Period 3 Electronegativity trend
Across the period, NC increases, SE remains relatively constant since electrons are added to the same shell-> ENC increases
Therefore stronger electrostatic forces of attraction between the nucleus and the electron pair in a covalent bond, electronegativity increases.
Electrical conductivity and structure of Na, Mg and Al
Giant metallic lattice structure
High electrical conductivity:
presence of sea of delocalized electrons as mobile charge carriers to conduct electricity.
Electrical conductivity and structure of Si
Giant molecular
Low electrical conductivity as Si is a metaloid
Electrical conductivity and structure of P, S, Cl, Ar
Simple molecular structure
Non-conductors of electricity in any state
-electrons are localized in covalent bonds and there are no mobile electrons to conduct electricity
Na2O with water
Dissolves completely in water
Na2O + H2O -> 2NaOH pH 14
MgO with water
Dissolves partially due to high LE of MgO
MgO + H2O -> Mg(OH)2 pH 9
Al2O3 with water
does not dissolved bc of high LE pH 7
SiO2 with water
no reaction bc of strong covalent bonds pH 7
P4O10 with water
dissolves in water
P4O10 + H2O -> H3PO4 pH 2
SO3 with water
dissolved in water
SO3 + H2O -> H2SO4 pH 2
Al(OH)3 with acid
Forms salt and water
Al(OH)3 + 3H+ -> Al3+ +3H2O
Al(OH)3 with base
Dissolves in excess to form colourless complex
Al(OH)3 + OH- -> Al(OH)4-
Na2O/MgO with base
No reaction
Na2O/MgO with acid
Form salt and water
AlO3 with acid
Forms salt and water
AlO3 + 6HCl -> 2AlCl3 + 3H2O
AlO3 with base
Dissolves in excess to form colourless complex
Al2O3 + 2NaOH + 3H2O -> 2NaAl(OH)4
SiO2, P4O10, SO3 with acid
No reaction
SiO2 with base
Reacts with hot concentrated NaOH
SiO2 + NaOH -> Na2SiO3 + H2O
P4O10 with base
P4O10 + 12NaOH -> 4Na3PO4 + 6H2O
SO3 with base
SO3 + 2NaOH -> Na2SO4 + H2O
NaCl with water
undergoes hydration, not hydrolysis
MgCl2, AlCl3 with water
Undergoes hydration , undergoes slight hydrolysis
SiCl4, PCl5 with water
Does not undergo hydration, undergoes complete hydrolysis (atoms have vacant and energetically available 3d orbitals to accept the lone pair from H2O, forming a dative bond.
Why does CCl4 not hydrolyse in water
C has no energetically accessible d-orbitals for dative bonding with H2O molecules
Difference between hydration and hydrolysis
hydration- formation of ion-dipole interactions
hydrolysis- chemical reaction
Observations of NaCl in water
dissolves completely pH 7
Observations of MgCl2 in water
dissolved completely pH 6.5
Observations of AlCl3 in water
dissolves completely in excess
forms white solid with white fumes of HCl in limited amount of water pH 3
Observations of SiCl4 in water
Reacts violently with water, evolving heat and white fumes of HCl pH2
Observations of PCl5 in water
Dissolves completely in excess, reacts violently in limited amount of water, evolving heat and white fumes of HCL pH 2
Explain the trend of thermal stability of Group 2 metal carbonates down the group
Down the group, IR of cations increases, charge density decreases-> polarizing power decreases, electron cloud less distorted.
C-O bond weakened to smaller extent, energy needed to break the C-O bond increases, ease of decomposition decreases.
Group 17 Electronegativity trend
Down the group, AR increase, electrostat att decrease, tendency to attract electrons decreases, electronegativity decreases
Explain the trend of volatility down Group 17 elements
Down the group, size of electron cloud increases, more easily polarized, strength of idid attractions increase, more energy needed to overcome, boiling point increases down the group, volatility decreases.
Explain the trend of Group 17 halogens as oxidizing agents
Down the group, AR increases, attraction decreases, tendency to gain electron decreases, strength as OA decreases
Trend of thermal stability for Group 17
From Cl to I, AR increases, effectiveness of orbital overlap decreases, bond strength decreases, energy needed to break the bond decreases, thermal stability decreases
