DM - Transition metals Flashcards
Where are transition metals found in the periodic table?
In the d-block (in the middle of the periodic table).
Most of the elements in the d-block are what?
Transition metals.
Which d-block elements do we mainly need to know?
Those in the first row from titanium to copper.
What is a transition metal?
A d-block element that can form at least one stable ion with an incomplete d sub-shell.
How many electrons can a d sub-shell hold?
10
What must a transition metal form?
At least one ion that has between 1 and 9 electrons in the d sub-shell.
Which elements in period 4 in the d-block are transition metals?
All except scandium and zinc.
Which of the transition metals electron configurations are different?
chromium and copper.
How is the electron configuration of chromium different?
It prefers to have one electrons in each orbital of the 3d subshell and one in the 4s subshell to give it more stability.
How is the electron configuration of copper different?
Prefers to have a full 3d subshell and just one electron in the 4s subshell to be more stable.
What stable ion does copper form?
Cu2+ ion by losing 2 electrons. The Cu2+ ion has an incomplete d subshell.
Why isn’t scandium a transition metal?
Because is only forms one ion, SC3+, which has an empty d subshell.
Why isn’t zinc a transition metal?
Only forms one ion, Zn2+, which has a full d subshell.
When ions are formed, which electrons are removed first?
The s electrons.
What stable ions does iron form?
Fe2+
Fe3+
What special chemical properties do transition metals have?
1) Can exist in variable oxidation states.
2) Can form coloured ions in solution.
What does it mean by transition metals can exist in variable oxidation states?
Iron can exist in the +2 oxidation state as Fe2+ ions and in the 3+ oxidation state as Fe3+ ions.
Copper can exist in the 1+ oxidation state as Cu+ ions and in the +2 oxidation state as Cu2+ ions.
What does it mean by transition metals can form coloured ions in solution?
Fe2+ ions are pale green.
Fe3+ ions are yellow.
Cu2+ ions are blue.
What colour are Fe2+ ions in solution?
Pale green.
What colour are Fe3+ ions in solution?
Yellow.
What colour are Cu2+ ions in solution?
(Pale) Blue.
Why aren’t Cu+ ions coloured in solution?
Because Cu+ ions are unstable in aqueous solution and disproportionate.
2Cu+ (aq) –> Cu2+ (aq) + Cu (s)
