23.1 General properties of transition metals
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Where do the transition metals element start and end What elements does this cut out and why
. Range from titanium to copper This cuts out scandium and zinc because transition metals need to have ions with a partially full d shell of electrons whereas these two don’t! Eg zinc forms Zn2+ ion (3d10) in all its compounds And scandium forms Sc3+ (3d0) in all its compounds As a result they are d block elements but not transition metal elements
Why are transition metals useful with the properties: . Conductivity . Appearance . Melting and boiling points
. They are good conductors of heat and electricity . They are hard, strong and shiny . They have high melting and boiling points These make them useful as they also have a low reactivity.
What is transition metal Fe useful
Iron and its alloy steel can be used for vehicle bodies and to reinforce concrete
How is copper used
. Water pipes
How is titanium used
. Jet engine parts that must withstand high temperatures
Why are transition metal elements similar
. In general there are two 4s electrons, and as you go across the period, electrons are added to the 3d subshell
What transition metal elements don’t fit the pattern
Copper and chromium because the d sub level is full (3d10) in copper and it is half full in chromium (3d5) and there is only one electron in the 4s outer level. A half full d level makes the atoms more stable in the same way a full outer main level makes the noble gas atoms stable. . It is 3d10 in copper because when the 3d sub shell has 9 electrons, it takes one from the 4s sub shell to get a full one. The same happens for chromium when there are 4 3d electrons, so it takes one from the 4s shell so one electron can go in each of the 5 orbitals
Give the electron configuration of V and then give it of V2+ Why are the electrons lost from the 4s sub shell before the 3d
1s2 2s2 2p6 3s2 3p6 3d3 4s2 1s2 2s2 2p6 3s2 3p6 3d3 Because once the sub shells are full, the 4s sub shell has more energy than the 3d sub shell so the electrons can be lost from it first
Electron configuration of the Cu element Give it of Cu2+
1s2 2s2 2p6 3s2 3p6 3d10 4s1 1s2 2s2 2p6 3s2 3p6 3d9
Electron configuration of Cr Cr3+ ion
1s2 2s2 2p6 3s2 3p6 3d5 4s1 1s2 2s2 2p6 3s2 3p6 3d3
What is the definition of a transition metal element
. An element that forms at least one stable ion with a partially full d shell of electrons
What are the 4 main features of chemical properties of transition metals
1) Variable oxidation states: 2) Colour: 3) Catalysis: 4) Complex formation
Describe the oxidation states of transition metals
Transition metals have more than one oxidation state in their compounds eg Cu(i) or Cu(ii). So they can take part in many redox reactions
Describe colour of transition metals
The majority of transition metals are coloured eg Cu2+ is blue
Describe the use of transition metals as catalysts
. Catalysts affect the rate of reaction without being used up or chemically changed in the reaction themselves. Many transition metals and their compounds show catalytic activity. Eg Iron is the catalyst in the haber process Vanadium oxide is the catalyst in the contact process Manganese(IV) oxide in the decomposition of hydrogen peroxide.
Describe use of transition metals in complex formation
. Transition metals form complex ions . A complex ion is formed when a transition metal ion is surrounded by ions or other molecules, collectively called ligands which are bonded to it by co-ordinate or dative bonds Eg [Cu(H2O)6]2+ is a complex ion formed when copper sulfate dissolves in water