n和l 均变动时, 出现能级交错
4s和3d、5s和4d
原子结构
2.在例题2-1中，我们说明了为什么Si和Ge相似，在周期表 这一列中的下一个元素是什么？它的电子构型怎样？
The next group IVB element in the series is Sn with an electron configuration (from the Periodic Table) of
invariant with time
• SOLUTION: Gold is one of the few metals whose pure metallic state is more thermodynamically stable than its oxide. Hence, gold does not oxidize. If it did, then it might gain or lose weight with time of exposure to air. • COMMENTS: This is why gold is found in nature as nuggets(天然金 块), whereas, for example, iron and aluminum are found as oxides or sulfides.
热力学与动力学
9.糖浆的流动速率可以描述为激活能约为50KJ/mol的，当温 度从10℃变化到25℃时，流动速率变化多少？
• • Data: R= 8.314 J/mol.K, K= C +273 Assumptions: Flow rate at temperature T is given by F(T)= Fo exp(-Q/RT)
热力学与动力学
8.在-1℃时能否得到纯的液态水。 • Solution: Yes, if the pressure of the system is raised above one atmosphere, water can exist at -1℃. • Comments: Since most of our daily experiences occur
l
1 1 1 p
2 2 d
3 f
s 轨道 球形
p 轨道 哑铃形
d 轨 道 有 两 种 形 状
磁量子数 ml
l 值相同的电子, 具有确定的电子云形状, 但在磁场中可以有不 同的伸展方向. 磁量子数就是描述电子云在空间的伸展方向 m可取 0，±1, ±2……±l （|m| l ） m 值相同的轨道互为等价(简并)轨道
the quantization of energy. If quantization of energy
did not exist, we would lose the ability to understand and predict properties based on valence electron configuration.
• COMMENTS: Elements can have different masses, from
having different numbers of neutrons. They are called isotopes.
原子结构
6.写出C的电子结构。C怎样才能形成4个相等的键？共价键 为高电子密度区域，因此相互排斥，预计在共价键合的C中4 个间的键合几何（键角）。 • sp3杂化：由一个ns轨道和3个np轨道混杂形成4个能量相 同的sp3杂化轨道，每个轨道含有1/4s成分和3/4p成分，各
at (or near) atmospheric pressure, we tend to forget
about pressure as an important system variable. There are, however, many important engineering processes that occur at either substantially higher or lower pressures.
两种可能的自旋方向:
正向(+1/2)和反向(-1/2)
产生方向相反的磁场
电子自旋
相反自旋的一对电子,
磁场相互抵消
•四个量子数与各电子层可能存在的电子运动状态数列 于下表。
主量子数 电子层 n=1 n=2 n=3 n=4 K L M N 原子轨道 符号 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 原子轨道数 1 1 3 1 3 1 3 5 5 7 电子运动 状态数 2 8 18 32
[1s22s22p63s23p63d104s24p64d10]5s25p2.
Note that the valence electron configuration for Sn is also of the form xs2xp2 with x=5.
原子结构
3.你预计Ca和Zn会表现出类似的性质吗？为什么？ Examination of the Periodic Table shows that Ca has the electron configuration [1s22s22p63s23p64s2] while Zn has configuration [1s22s22p63s23p63d10]4s2 Since both elements have two valence electrons (4s2) we should expect these elements to display some similar properties. Although Zn and Ca have similar valence electron configurations, they have other structural differences that result in differences in properties.
热力学与动力学
10．为了形成聚合物，许多等同的小分子在化学反应中被连接在一起。聚合反应 是放热的，或者说是产生热量的，它可描述成阿累尼乌斯过程，激活能约为 80KJ/mol。如果温度增加10℃，反应速率变化多少？
Data: R= 8.314 J/mole-K, K= C +273 Assumption: Polymerization rate at temperature T is given by P(T)= Po exp(-Q/RT) Solution: The ratio of the polymerization rates at any two temperatures is: P(T1) = Po exp(-Q/RT1) = exp(-Q/R(1/T1 - 1/T2)) P(T2) Po exp(-Q/RT2)
材料科学基础
第二章习题解答
原子结构
1. 第ⅢB族元素有多少个价电子？第ⅤB族有几个？ 第ⅢB族元素B（5）、Al（13）、Ga（31）、In（49）、 Tl（81）有3个价电子。第ⅤB族N （7） 、P （15） 、 As （33） 、Sb （51） 、Bi（83）有5个价电子。 1s/2s/2p/3s/3p/4s/3d/4p/5s/4d/5p/6s/4f/5d/6s/……
•
Solution: The ratio of the flow rates at any two temperatures is: F(T1) = Fo exp(-Q/RT1)； F(T2) ＝ Fo exp(-Q/RT2)
F(25C) = exp (-Q/R(1/T1-1/T2)) F(10C) = exp(-50,000J/mol/8.134J/mol-K)(1/298K- 1/283K)) = 2.91 A temperature increase of 15 C results in almost a factor of three increase in the flow rate of molasses（糖蜜）.
描述电子运 n
决定了电子在核外出现概率最大区域(“电子层”)，离核的远近及其
能量的高低.
n决定能量，n越大，电子的能量越高；n也代表电子离核的平均距离， n越大，电子离核越远。n相同称处于同一电子层。
n是一个非零的整数值，不同的n 值，对应于不同的电子层
P(T1) = exp[-Q/R((T2-T1)/T1T2))] = exp[-Q/R(T/T1T2)] P(T2) This form of the expression shows that the problem can not be solved with the information given. A knowledge of T is not sufficient. We must also know the two temperatures. Comments: When the temperature increases from 10 C to 20 C, the rate increases by a factor of 3.19. In contrast, a temperature increase from 40 C to 50 C results in a rate increase of 2.59. This example illustrates the general result that a fixed change in temperature has a greater influence on the reaction rate if the average temperature is low.
个sp3杂化轨道之间的夹角为109.5°。
激发 C原子轨道 杂化 4个sp3轨道
热力学与动力学