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Transition Metal Properties

Key Concepts

Transition metals are located in the middle of the Periodic Table and have an electron configuration filling the d-subshell .

s subshell d subshell p subshell

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Transition Metals

In comparison with main group metals, transition metals generally show:

higher densities
higher melting and boiling points
higher ionisation energies
a range of oxidation states
colours in their compounds
the ability to form a wide range of coordination compounds
paramagnetism (ability to attract a magnetic field)
less chemical reactivity than Group I (Alkali) metals and Group II (Alkali Earth) metals

Hardness, Density, Melting and Boiling Point

	Transition Metals						Non-Transition Metals
Symbol	V	Cr	Mn	Fe	Co	Cu	Na	Mg	Al	K	Ca	Ba
Atomic Number (Z)	23	24	25	26	27	29	11	12	13	19	20	56
Valence Shell Electron Configuration	3d³4s²	3d⁵4s¹	3d⁵4s²	3d⁶4s²	3d⁷4s²	3d¹⁰4s¹	3s¹	3s²	3s²3p¹	4s¹	4s²	6s²
Density (g cm^-3)	6.1	7.2	7.4	7.9	8.9	8.9	0.97	1.7	2.7	0.86	1.6	3.5
Melting Point (^oC)	1900	1900	1250	1540	1490	1083	98	650	660	64	838	714
Boiling Point (^oC)	3450	2642	2100	3000	2900	2600	892	1110	2450	770	1490	1640

Transition metals have smaller atomic volumes than Group I and II metals because additional electrons are being progressively added to the inner atomic orbitals resulting in stronger attraction to the nucleus.
These atoms of smaller volume can pack together more closely resulting in higher densities and hardness.
Closer packing results in stronger bonding so more energy is required to melt or boil transition metals.

Ionisation Energy and Chemical Reactivity

	Transition Metals						Non-Transition Metals
Symbol	V	Cr	Mn	Fe	Co	Cu	Na	Mg	Al	K	Ca	Ba
Atomic Number (Z)	23	24	25	26	27	29	11	12	13	19	20	56
Valence Shell Electron Configuration	3d³4s²	3d⁵4s¹	3d⁵4s²	3d⁶4s²	3d⁷4s²	3d¹⁰4s¹	3s¹	3s²	3s²3p¹	4s¹	4s²	6s²
First Ionisation Energy (kJ mol^-1)	656	659	724	766	764	752	502	744	584	425	596	509

The smaller atomic radii of transition metals means the valence shell (outer-shell) electrons are more strongly attracted to the nucleus and therefore less easily removed resulting in higher first ionisation energies compared to Group I and II metals.
Because electrons are less easily lost, the transition metals are less chemically active than Group I and II metals.
The lower chemical reactivity of the transition metals means they will be placed lower down in the activity series of metals compared to Group I and II metals.
Since oxidation relates to the loss of electrons, transition metals are less easily oxidised than Group I and II metals.

Oxidation States

	Transition Metals						Non-Transition Metals
Symbol	V	Cr	Mn	Fe	Co	Cu	Na	Mg	Al	K	Ca	Ba
Atomic Number (Z)	23	24	25	26	27	29	11	12	13	19	20	56
Valence Shell Electron Configuration	3d³4s²	3d⁵4s¹	3d⁵4s²	3d⁶4s²	3d⁷4s²	3d¹⁰4s¹	3s¹	3s²	3s²3p¹	4s¹	4s²	6s²
Common Oxidation States	+2 +3 +4 +5	+2 +3 +6	+2 +3 +4 +6 +7	+2 +3	+2 +3	+1 +2	+1	+2	+3	+1	+2	+2

The energies of the 3d and 4s orbitals are very close.
Often the lowest oxidation is +2 corresponding to the loss of 2 ns orbital electrons.
Higher oxidation states correspond to the additional loss of (n-1)d orbital electrons.
The decrease in maximum states after manganese in the first transition metal series (and after iridium in the second series and osmium in the third series) reflects the difficulty of breaking into a half-filled d subshell.

Coloured Compounds

	Transition Metals						Non-Transition Metals
Symbol	V	Cr	Mn	Fe	Co	Cu	Na	Mg	Al	K	Ca	Ba
Atomic Number (Z)	23	24	25	26	27	29	11	12	13	19	20	56
Valence Shell Electron Configuration	3d³4s²	3d⁵4s¹	3d⁵4s²	3d⁶4s²	3d⁷4s²	3d¹⁰4s¹	3s¹	3s²	3s²3p¹	4s¹	4s²	6s²
Common Oxidation States	+2 +3 +4 +5	+2 +3 +6	+2 +3 +4 +6 +7	+2 +3	+2 +3	+1 +2	+1	+2	+3	+1	+2	+2
Colour of Chloride Compound	VCl₂ green	CrCl₃ red	MnCl₂ pink	FeCl₂ yellow	CoCl₂ blue	CuCl₂ yellow	NaCl white	MgCl₂ white	AlCl₃ white	KCl white	CaCl₂ white	BaCl₂ white
Colour of Aqueous Solution (Mⁿ⁺)	V²⁺ violet	Cr²⁺ blue	Mn²⁺ pink	Fe²⁺ green	Co²⁺ pink	Cu²⁺ blue	Na⁺ colour- less	Mg²⁺ colour- less	Al³⁺ colour- less	K⁺ colour- less	Ca²⁺ colour- less	Ba²⁺ colour- less

A substance will appear coloured if it absorbs light from some portion of the visible spectrum.
Ions with d orbital electrons appear coloured because energy from visible light is absorbed and used to promote a d orbital electron to a higher energy d sublevel (referred to as d-d transitions).
Ions with no d orbital electrons are colourless, eg, Sc³⁺, Ti²⁺.
Ions with d¹⁰ electron configurations are colourless, d-d transitions are impossible because the d orbitals are all filled, eg, Zn²⁺

Paramagnetism

	Transition Metals						Non-Transition Metals
Symbol	V	Cr	Mn	Fe	Co	Cu	Na	Mg	Al	K	Ca	Ba
Atomic Number (Z)	23	24	25	26	27	29	11	12	13	19	20	56
Valence Shell Electron Configuration	3d³4s²	3d⁵4s¹	3d⁵4s²	3d⁶4s²	3d⁷4s²	3d¹⁰4s¹	3s¹	3s²	3s²3p¹	4s¹	4s²	6s²
Paramagnetism of Aqueous Ions	Yes V³⁺	Yes Cr²⁺ Cr³⁺	Yes Mn²⁺ Mn³⁺	Yes Fe²⁺ Fe³⁺	Yes Co²⁺	Yes Cu²⁺	No Na⁺	No Mg²⁺	No Al³⁺	No K⁺	No Ca²⁺	No Ba²⁺

Paramagnetism is a weak attraction into a magnetic field.
Substances with unpaired electrons can be paramagnetic.
Paramagnetism is caused by both the orbital and spin motions of electrons (any rotating or revolving charged object generates a magnetic field).
The magnetic fields of paired electrons cancel out, so only unpaired electrons contribute to paramagnetism.

Ferromagnetism

Ferromagnetism is a strong attraction into a magnetic field.
Ferromagnetism occurs when atoms with unpaired electron spins are just the right distance apart to permit the individual spins to align with each other within a relatively large region.
The individual spins within this region act cooperatively resulting in a large magnetic effect.
Only solids can show ferromagnetism.
The only ferromagnetic elements at room temperature are iron, cobalt and nickel.
Ferromagnetic compounds such as CrO₂ and Fe₃O₄ also exist.