Transition metals 202-203

Question 1

Define a transition element.

Answer 1

A transition element is a d-block element that forms an ion with an incomplete d sub-shell.

Question 2

Why is scandium and zinc not calssified as transition metals?

Answer 2

They do not have ion with partially filled d-orbitals.

• Scandium forms only the Sc³⁺ ion, in which d-orbitals are empty.
• Zinc forms only the Zn²⁺ ion, in which the d-orbitals are completely full.

Question 3

What are the rules for electrons filling up orbitals covered in AS chemistry?

Answer 3

• In a subshell, one electron fills up one orbital, once all orbitals in a subshell contain one electron, another electron is added to the orbitals so theres pairs of electrons in each orbital with opposite spin.

Question 4

Explain how chromium and copper do not fill the pattern of filling sub-shells?

Answer 4

They do not follow the Aufbau principle for placing electrons in orbitals:

• chromium - the 3d and 4s orbitals all contain one electron with no orbital being completely filled.
• copper - the 3d orbitals are full, but there is only one electron in the 4s orbital.

Question 5

Explain when forming positive ions, why transition metals lose their 4s electrons before the 3d electrons.

Answer 5

The 3d and 4s energy levels are very close together and, once electrons occupy the orbitals, the 4s electrons have a higher energy and are lost first.