Further across the block, the radii begin to increase slightly. There are so many d-electrons that the e-e repulsion increase more than the effective nuclear charge.
化肥（2/3），石化产品，染料，清洁剂。
锌汞齐
+5,
+4, +3, +2
MnO4MnO2 VO43-

VO43-,VO2+,V3+,V2+
VO2+
V3+ V2+
Chromium, Cr (the name comes from chroma, Greek for color) Bright, lustrous, corrosion-resistant metal. FeCr2O4(s) + 4C(s) △→ Fe(s) + 2Cr(s) + 4CO(g) or
(higher nuclear charge and the poor shielding effect of the felectrons)
The densities (g/cm3) of d-metals at 25°C. The
lanthanide contraction has a pronounced effect on the densities of the elements in Period 6, which are among the densest of all the elements.
Because the atomic radii of the d-block elements are so similar the atoms of one element can replace the atoms of another element with minor modification of the atomic locations. Consequently, a wide range of alloys can form.
• The range of oxidation states of each d-metals. At the ends of each row (Sc, Zn), in one oxidation state other than zero. Close the center of each row, in at least two oxidation states (Mn). The second, and third rows, higher oxidation states. • A species in which an element is in a high oxidation state tends to be a good oxidizing agent. MnO4-(aq)+8H+(aq)+5e- →Mn2+(aq)+4H2O(l) Eo=+1.51V • Most d-metal oxides are basic, the oxides of a given element show a shift toward acidic character with increasing oxidation number. Cr(II)O Cr2(III)O3 Cr(VI)O3 basic amphoteric acidic
Ti(s) + 2MgCl2(s)
TiO2 brilliantly white, nontoxic, stable solid used as white pigment in paints and paper. Semiconductor in the presence of light, used as electrode in photoelectrochemical cells. BaTiO3, piezoelectric(压电).
分占不同的区域， 相对远离，互斥小。
2) Electron density in d-orbitals is low near nucleus. Not very effective at shielding other electrons from the nuclear charge.
接近核处电子密度低， 屏蔽弱
例外: Hg, low melting point, Liquid(RT) Cu, red-brown and Au, yellow.
1) The lobes of two d-orbitals on the same atom occupy markedly different regions of the space. Relatively far apart, repel one another weakly.
La-Lu
Atomic radii of the d-block elements (pm). Notice the
similarity of all the values and, in particular, the close similarity between the second and third rows as a result of the lanthanide contraction. (From 224pm for Ba to 172pm for Lu)
Nuclear charge and the number of d-electrons both increase from left to right across each row. Because the repulsion between delectrons is weak, the increasing nuclear charge can draw them inward, so the atom becomes smaller.
“Transition” metals
过渡金属的特性
• 变价性 • 配合物 • 颜色 • 磁性
From highly reactive metals of the s block to the much less reactive metals of Group 12 and the p block.
a) Before magnetization, the spins are almost randomly aligned. b) After magnetization the spins are aligned in the same direction.
Trends in Chemical Properties
Vanadium, V
V2O5(s) + 5 Ca(l) △→ 2V(s) + 5CaO(s) VCl2(s) + Mg(l) △→ V(s) + MgCl2(s) or or electrolysis
Ferrovanadium, V 86%, C 12%, Fe 2%. + Fe,C(l) → V steel Tough steels for automobile and truck springs.
Trends in Physical Properties
• All the d-block elements are metals. • Most, good electrical conductors. • Most, malleable, ductile(延展), lustrous(光 泽), silver-white in color. • Generally, higher melting and boiling points.
Scandium through Nickel
前过渡元素
后过渡元素
Scandium, Sc
Isolated in 1937, a reactive metal.
1) Sc react with water about as vigorously as Ca does.
2) The small, highly charged Sc3+ ion is strongly hydrated in water (like Al3+), the resulting hydrated ion is about as strong a Bronsted acid as acetic acid.
SO2，SO3, H2S(IV)O3, H2S(VI)O4
S + O2 → SO2; 植被分解和火山爆发；燃油和煤(电厂) H2S(g) + 3O2(g) → 2SO2(g) + 2H2O(g)
酸性氧化物
SO2(g) + H2O(l) → H2SO3(aq) 还原性和氧化性
SO2(g) + Br2(aq) → Br-(aq) + SO4-(aq)
Ferromagnetic materials
include Fe, Co, Ni, Gd, CrO2, magnetite.
They contain regions of atom in which electrons of many atoms spin in the same direction and give rise to a strong magnetic field.
周期
四
五
六
These three artifacts represent the progress that has been made in the extraction of d-metals.(a) An ancient bronze (青铜，Cu/Sn) chariot axle cap from China, made from an alloy of metals hat are easy to extract. (b) A nineteenth-century iron steam engine made from a metal that was moderately easy to extract once high temperatures could be achieved. (c) A 20-century airplane engine with titanium components that had to await advanced, hightemperature technology before the element became widely available.