Transition metals, Isomerism, Period 3 chlorides and oxides Flashcards
Whats the difference between D-block elements and transition metals
All elements between period 3 to 12 are in the D-block however only elements that have partially filled d-subshells are transition metals
general electronic configuration of transition metals and outliers
- [Ar]3dn4s2
- Chromium = [Ar]3d5 4s1 - more energetically favourable
- Copper = [Ar]3d10 4s1
Trend of ions formed by transition metals
- +3 common up to manganese
- manganese up to +7 and chromium up to +6
- +2 common after manganese
Whats a ligand
- either neutral or anion
- lewis base
- donate a pair of electrons through a dative covalent bond to metal ion
Whats a coordination number
The number of ligands surrounding a molecule in a complex
Shapes of complexes with different coordination numbers
2 - linear
4 - tetrahedral (common)
4 - square planar if the molecule has 8 electrons in the d subshell (rare)
6 - octahedral
Whats an enantiomer
- A molecule that has two non-superimposable mirror images
- Polarised light bounces off them in opposite directions
What is Kstab
- Stability constant
- ∑[products]/∑[reactants]
- H2O isnt included as its in excess
Whats a chiral centre
A carbon joined by 4 unique atoms/groups
Reactions of period 3 elements
- They react with oxygen in a combustion reaction where oxygen is the reducing agent
- They react with chlorine which also acts as an oxidising agent
Trend of oxidation number and apparence of period 3 chlorides
- General increase as you go across the period from +1 to +4
- P can be +3 or +5
- S can be +1,+2 or +4
- White solid up to Al
- All after are liquid except PCl5 which is white solid
Trend of melting point of period 3 chlorides
- General decrease, P goes up
- Na and Mg show ionic bonding (giant ionic lattices) whereas the rest is covalent (simple molecular)
Properties of giant ionic lattices
- High melting point
- Highly soluble in water
- Electrical insulators when solid
- Electrical conductors when molten or dissolved
- Breaking the lattice is exothermic
Hydrolysis of period 3 chlorides
- Ionic lattices dissolve in water
- Silicon IV - Water attacks the Si and releases 2HCl and SiO2
- Phosphorus - Hydrolysed to release HCl
- Al - Al3+ formed and a hydrogen can be released to form 2+
Trends of oxidation numbers and apperance of period 3 oxides
- +1 to +4 for the first 4
- P - +3 and +5
- S - +4 and +6
- Cl - +1 and +7
- White solid up to P
- S is a colourless gas
- ClO+1 is a yellow gas, Cl2O7 is a colourless liquid
Trend of melting points of period 3 oxides
- Increase from Na to Mg then steady decrease
- Na2O, MgO and Al2O3 are ionic so they have high MP
- Mg2+ has a much higher charge density so has stronger ionic bonding
- SiO is giant covalent
- The rest are simple covalent
Trend of melting points of period 3 oxides
- Increase from Na to Mg then steady decrease
- Na2O, MgO and Al2O3 are ionic so they have high MP
- Mg2+ has a much higher charge density so has stronger ionic bonding
- SiO is giant covalent
- The rest are simple covalent
Characteristics of ionic oxides
- They can accept protons making their solutions alkaline
- Al2O3 can act as a base or acid - its amphoteric
Properties of SiO2
- Each Si bonded to 4 oxygens
- High melting point
- Doesn’t dissolve in water or conduct electric
Properties of simple covalent oxides
- P4O10 has a higher MP than P4O6 as it is larger and has more room for van der waals forces
- SO3 has a higher MP than SO2 as its planar and can stack, both polar
- Cl2O and Cl2O7 are both polar but the latter has a higher MP as its bigger
- They all dissolve in water to produce an acid
What makes transition metals have colour
- Their incomplete d-subshell as electrons get excited between d-orbitals with higher energy that can absorb light
- Zinc is colouless as it has a full subshell
- They absorb certain wavelengths of light and whats reflected is seen
- The colour seen is the opposite of whats seen
What can change the colour of the solution
- Changing the ligand changes the size of the gap between d-orbitals
- Different oxidation states
Whats a catalyst
A substance that regenerates after use and provides an alternative pathway that has a lower activation energy
Difference between hetero and homogeneous
Hetero - The catalyst is not in the same state as the reactants
Homo - The catalyst is in the same state as the reactants
