Module 5 Chapter 2
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What the transition elements
D-block elements that are found between groups 2 and 13
What is a feature of the order in which the sub shells are filled by a d-block element
When forming an atom d-block elements fill the 4s sub-shell before the 3d sub-shell
What is a feature of the order in which the sub shells are emptied by a d-block element in ion formation
In ion formation loses 4s electrons before 3d electrons
What is an exception to this trend in how subshells are filled
For chromium and copper a 4S2 electron is promoted to half full or fully fill the 3D sub-shells respectively
What is the electron configuration of chromium and copper
Chromium - [Ar] 3S2 3P6 4S1 3D5 Copper - [Ar] 3S2 3P6 4S1 3D10
Why do chromium and copper atoms fill the subshells in this way
Although promoting a 4s electron raises the sub-shells energy level this is negated by creating a more energetically stable half/fully filled 3d sub-shell
What happens when transition metals form positively charged ions
They lose their 4s electrons before losing any of the 3d electrons
What is the definition of a transition metals
An element that forms an ion with a partially filled d subshell
What elements are transition elements but don’t fit the definition of a transition metals
Scandium and zinc as scandium only forms a +3 ion and zinc only forms a +2 ion, with a full 3D subshell in zinc and an empty 3D subshell in scandium
What are the properties of transition metals that are the same as other metals
High melting points and boiling points Shiny Conduct electricity and heat
What are properties that are unique to transition metals
Variable oxidation states Coloured compounds Elements and compounds can act as catalysts
What is a feature of how the number of oxidation states in a transition metal varies across a period
The number of oxidation states increases across the transition elements until manganese then it will decrease
What is a feature of all transition elements
They form compounds with an oxidation number of +2
When are these transition metal compounds coloured
When they are dissolved in water = coloured solution
What is colour linked to
The partially filled d-orbitals and can vary with oxidation states
What are some examples of transition metals catalyst
Haber process - iron catalyst (fertiliser production as makes ammonia) Contact process - vanadium (v) oxide (sulphuric acid, fetilisers) Hydrogenation of vegetable fats - nickel catalyst Decomposition of hydrogen peroxide - manganese (IV) oxide catalyst
When do complex ions form
When a metal ion is centrally bonded to one or more molecules or negative ions known as ligands
What do ligands do
They donate a pair of electrons to form a dative bond (or coordinate bond) with the central metal ion
What is the coordinate number
The number of dative bonds made
What are the two types of ligands
Monodentate Bidentate
What are monodentate ligands and examples
Ligands that donate 1 pair of electrons to the central metal ion Examples: water, ammonia, chloride, cyanide, hydroxide
What are bidentate ligands and examples
Donate 2 pairs of electrons to central metal ion Examples: diaminoethane, oxalate
What is the shape of complex ions with 6 coordinate numbers
They have an octahedral shape with a bond angle of 90*
What is the shape of 4 coordinate complex ions
Tetrahedral - 109.5* around the central ion Square planar - bond angle of 90*