在金属活动性顺序表里，金属的位置越靠前，它的活动性就越强，在

问题问答题

在金属活动性顺序表里，金属的位置越靠前，它的活动性就越强，在化学反应中越容易失去电子．

（1）Ca、Mg、K三种金属在化学反应中失去电子的能力由强到弱的顺序是______．

（2）Ca、Mg、K三种金属的原子结构示意图如右图所示，请根据这三种金属的原子结构示意图，结合已学过的有关原子结构的知识推测：金属单质失去电子能力的强弱主要与哪些因素有关？______（任答两点）．

（3）能证明Cu的金属活动性比Ag强的方法是：______（用化学方程式表示）．

（4）非金属单质也具有类似金属与盐溶液之间的置换反应规律，即活动性较强的非金属可把活动性较弱的非金属从其盐溶液中置换出来．例如，在溶液中可发生以下反应：Cl₂+2NaBr=2NaCl+Br₂； Br₂+2KI=2KBr+I₂↓；I₂+Na₂S=2NaI+S 由此可以判断硫（S）、溴（ Br₂）、碘（I₂）、氯气（Cl₂）四种非金属单质的活动性由弱到强的顺序的是______．

答案

（1）Ca、Mg、K三种金属活动性强弱顺序为K＞Ca＞Mg，故根据题目所给信息可知，在化学反应中失去电子的能力由强到弱的顺序是K＞Ca＞Mg．

（2）决定元素化学性质的是最外层电子数，原子的电子层数越多，在最外层电子数一定的条件下，就越容易失去电子，故金属单质失去电子能力的强弱主要与最外层电子数、电子层数有关．

（3）由于铜的化学性质比银活泼，因此可以选择铜和硝酸银溶液反应来证明铜比银活泼．

（4）非金属单质也具有类似的置换反应规律，即活动性较强的非金属可把活动性较弱的非金属从其盐溶液中置换出来，由反应C1₂+2NaBr=2NaCl+Br₂可得非金属性C1₂＞Br₂，同理可得I₂＞S，Br₂＞I₂，故选C1₂＞Br₂＞I₂＞S．即四种非金属单质的活动性由弱到强的顺序的S＜1₂＜Br₂＜C1₂．

故答案为：（l）K＞Ca＞Mg；

（2）最外层电子数；电子层数；

（3）Cu+2AgN0₃=Cu（N0₃）₂+2Ag；

（4）S＜1₂＜Br₂＜C1_2（或硫＜碘＜溴＜氯气）．

阅读理解。
1. Where are the rainforests? Rainforests cover six per cent of the Earth’s surface. There are rainforests in many parts of the world but the biggest forests are in South America, Africa and South East Asia. There aren’t any rainforests in Europe or North America. 2. What’s in the rainforests? About 75% of all the types of animals that we know come from rainforests. Thousands and thousands of animals live in rainforests. There are many very beautiful birds, insects and reptiles. Many of them live in the trees, more than 30 metres from the ground. There are also thousands of different plants-and lots of tall trees! It is always hot in a rainforest and the ground is always wet. It is also dark.
3. Why are the rainforests important? The rainforests are very important for us. We need them! The trees and other plants in the forest help to make the air that we breathe. They give us wood, rubber, fruits and many of our medicines.
4.__________________________ Unfortunately, in many places, the rainforests are in danger. For example, many years ago there was a large rainforest in Java. There were thousands of different plants and animals in the forest, but now there is nothing. People chopped down the trees because they wanted to grow rice. Many animals lived in the rainforest. Some of them went to other parts of Java but many of them disappeared - forever. The same thing is happening now in many other parts of the world. The rainforests are in danger.
1. In which of the following places can we find rainforests according to Paragraph 1?
A. In the UK. B. In Asia. C. In the USA. D. In France.
2. Which of the following belongs to a kind of “reptile”?
A. A sparrow. B. A swallow. C. A snake. D. A butterfly.
3. Which might be the best title for Paragraph 4?
A. What’s happening to the rainforests? B. What can we find in the rainforests in Java? C. Why did people chop down the trees in the rainforests? D. Why did many plants and animals disappear in the rainforests?
4. What is the writer’s purpose of writing the article?
A. To tell us how to survive in the rainforests. B. To help us know some living things in the rainforests. C. To tell us to care about the protection of the rainforests. D. To give us advice on how to make full use of the rainforests.