Properties of transition elements Flashcards
Where are d block elements located?
- between group 2 and 13
What are d block elements?
- They have their highest energy electron in a d subshell
- They are all metallic, have high melting and boiling points and can conduct electricity and heat
State the electron configuration of elements for Ti - Cu?
What are the exceptions in electron configuration for d block elements?
chronium = 1s2 2s2 sp6 3s2 3p6 3d5 4s1
Copper = 1s2 2s2 2p6 3s2 3p10 4s1
- they do not p;ace electons singly in orbitals before pairing for stability
- A half filled d5 sub shell and a fully filled d10 sub shell give additional stability for chronium and copper
What are transition elements?
- defined as d block elements that form at least one ion with a partially filled d orbital
What are the two exceptions of d block elements for transition metals?
- Scandium only forms sc3+ by the loss of two 4s electrons and one 3d electron
- this makes its electron configuration for sc3+ = 1s2 2s2 2p6 3s2 3p6, this means it has no partailly filled d orbital and therefore is not a transition element
- Zinc only forms Zn2+ by the loss of two 4s electrons and has the electron configuration of Zn2+ = 1s2 2s2 2p6 3s2 3p6 3d10, this means it has a full d orbital and therefore is not a transition element
What are properties of transition elements?
- form compounds in which the transition element has different oxidation states
- form coloured compounds
- can act as catalysts
What are the variable oxidation states of transition elements?
- transition elements can form compounds with more than one oxidation states
- for example, Fe3+ and Fe2+
- each transition element forms a compound with an oxidation number of +2
- each oxidation state has a characteristic colour
What is the trend of oxidation states across the transition elements?
- the number of oxidation states increases across to manganese and then decreases
What type of compounds and ions do transition metals form?
- they form coloured compounds and ions
- solid compounds can be dissolved in water to from coloured solutions
- the colour of the solution is linked to the partially filled d orbital and can vary between different oxidation states
How do transition metals act as catalysts?
- catalyses increase the rate of chemical reactions without changing and provide and alternative reaction pathway with a lower activation energy
- heterogeneous catalysts = catalysts that are in a different state to reactants
- homogeneous = catalysts that are in the same state as reactants
What are examples of homogeneous catalysts?
- copper used to catalyse reactions of zinc and acids
What are examples of heterogenous catalysts?
- the haber process = uses iron catalysts
N2 + 3H2 = 2NH3 - the contact process = uses a vandium oxide catalyst (V205)
- hydrogenation of alkenes = uses a nickel catalyst
