|
所在平台: Udemy |
课程主页: https://www.udemy.com/course/s-block-elements/
课程评论：没有评论
**课程名称：** s区元素 **课程概述：** 本课程深入探讨元素周期表中s区元素的化学性质和重要性。s区元素是指其最后电子填充在s轨道的元素，主要包括化学周期表第一族（碱金属）和第二族（碱土金属）的元素。 **课程内容亮点：** * **碱金属（第一族）：** 详细介绍锂（Li）、钠（Na）、钾（K）、铷（Rb）、铯（Cs）和钫（Fr）的性质，它们最外层有一个电子，与水反应生成强碱（氢氧化物），因此被称为碱金属。 * **碱土金属（第二族）：** 重点讲解铍（Be）、镁（Mg）、钙（Ca）、锶（Sr）、钡（Ba）和镭（Ra）的特性，它们最外层有两个电子。除铍外，通常被称为碱土金属。 * **物理性质：** 强调了碱金属和碱土金属的低密度，因此也被称为“轻金属”。 * **化学反应性与存在形式：** 阐述了碱金属和碱土金属的强反应性，导致它们在自然界中通常以化合态存在，而非游离态。课程将细致地介绍它们常见的存在形式，例如卤化物、氧化物、硅酸盐、硼酸盐、硝酸盐、碳酸盐、硫酸盐和磷酸盐。 * **地壳丰度：** 揭示了钙、镁、钠、钾、钡和锶在地壳中的丰度排名，以及它们在海水、盐井和盐湖中的存在。 * **第一元素的反常行为：** 深入分析了每个族中第一种元素的特殊性，这归因于其原子半径小、电离能/电负性高、价层缺乏空d轨道以及阳离子的高极化能力。 **课程目标：** 通过学习本课程，您将全面掌握s区元素（碱金属和碱土金属）的基本概念、化学性质、在自然界中的分布以及其在周期表中的独特地位。
The elements in the long form of the periodic table has been divided into four blocks, namely s, p, d & f blocks. The elements of group I & II receive their last electron in s-orbital. So they are called as s - block elements.The metals Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and francium (Fr) which have one electron in their outermost shell belongs to group I and are called alkali metals as they react with water to form hydroxides which are strong bases or alkalies.The elements of group II are Beryllium (Be), Magnesium (Mg), Calcium (Ca),Strontium (Sr), barium (Ba) and radium (Ra) which have two electrons in their outermost shell. All these elements are also metallic in nature and are commonly known as alkaline earth metals with the exception of beryllium. Because of their low density, alkali metals and alkaline earth metals are called lighter metals. Both alkali and alkaline earth metals are highly reactive and hence do not occur in free state but found in combined state. Whereas alkali metals mostly occur as halides, oxides, silicates, borates and nitrates, alkaline earth metals mainly occur as silicates, carbonates, sulphates and phosphates. Some alkali & alkaline earth metals occur abundantly in nature. Calcium is the fifth, magnesium is the sixth, sodium is seventh and potassium is eight barium is the fourteenth and strontium is the fifteenth most abundant element by weight in the earth's crust. Sodium and magnesium are also present in sea water brine wells and few salt lakes.Anomalous behaviour of first elementThe first element of a group differs considerably from the rest of the elements of the same group. This anomalous behaviour is due to(i) Smaller size of their atoms(ii) Their higher ionization energies(iii) Their higher electronegativities(iv) Absence of vacant d - orbitals in their valence shell(v) High polarizing power of its cation.
