The Group 2 metals · 第 2 族金属
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| alkaline earth metal/ˈælkəlaɪn ɜːθ ˈmetl/ | 碱土金属 | jiǎn tǔ jīn shǔ |
| reactivity/rɪəkˈtɪvɪti/ | 反应活性 | fǎn yìng huó xìng |
| hydroxide/haɪˈdrɒksaɪd/ | 氢氧化物 | qīng yǎng huà wù |
| carbonate/ˈkɑːbəneɪt/ | 碳酸盐 | tàn suān yán |
The alkaline earth metals 碱土金属
- Group 2 holds magnesium, calcium, strontium and barium.
- They all have two outer electrons, lost to form 2+ ions.
- They get more reactive down the group.
碱土金属
- 第 2 族(Group 2)包含镁、钙、锶和钡。
- 它们都有两个外层电子,失去形成 2+ 离子。
- 它们沿族向下更活泼。
Group 2 reactivity ladder · 第 2 族反应性阶梯
Move down Group 2 and see why reactions become more vigorous. · 沿第 2 族向下移动,看为什么反应变得更剧烈。
Group 2 metals form ions with a 2+ charge. · 第 2 族金属形成带 2+ 电荷的离子。
They lose their two outer electrons. · 它们失去它们的两个外层电子。
Why reactivity 反应活性 rises
- Going down, the atoms get larger and hold their two outer electrons less tightly.
- So the electrons are lost more easily → reactivity increases down the group.
Magnesium, a Group 2 metal, burns with a brilliant white flame
为什么反应性上升
- 向下走,原子变得更大,把它们的两个外层电子抓得不那么紧。
- 所以电子更容易失去 → 反应性沿族向下增加。
镁,一种第 2 族金属,以灿烂的白色火焰燃烧
Reactivity increases down Group 2 because: · 反应性沿第 2 族向下增加,因为:
Larger atoms hold their two outer electrons less tightly, so they are lost more readily. · 更大的原子把它们的两个外层电子抓得不那么紧,所以它们更容易失去。
Reactions of the elements
- with oxygen: burn to an oxide — $2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$.
- with water: form a hydroxide 氢氧化物 + hydrogen (faster down the group) — $\text{Ca} + 2\text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{H}_2$. (Mg is slow with cold water, fast with steam.)
- with acid: form a salt + hydrogen — $\text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2$.
Limestone cliffs are calcium carbonate 碳酸盐, a Group 2 compound
元素的反应
- 与氧:燃烧成一个氧化物——$2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$。
- 与水:形成一个氢氧化物 + 氢(沿族向下更快)——$\text{Ca} + 2\text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{H}_2$。(Mg 与冷水慢,与蒸汽快。)
- 与酸:形成一个盐 + 氢——$\text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2$。
石灰岩悬崖是碳酸钙,一种第 2 族化合物
A Group 2 metal reacting with water forms: · 一种第 2 族金属与水反应形成:
e.g. Ca + 2H₂O → Ca(OH)₂ + H₂; the reaction gets faster down the group. · 例如 Ca + 2H₂O → Ca(OH)₂ + H₂;反应沿族向下变快。
Match each Group 2 fact to the right item. · 把每个第 2 族事实匹配到正确的项。
Each item links the term to its correct meaning. · 每一项把术语链接到它正确的含义。
Reactions of the compounds
- oxides and hydroxides are basic — they react with water and with acids.
- carbonates react with acids to give a salt, water and carbon dioxide:
$$\text{CaCO}_3 + 2\text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2\text{O} + \text{CO}_2$$
Group 2 reactivity increases down the group as atoms get larger
化合物的反应
- 氧化物和氢氧化物是碱性的——它们与水和与酸反应。
- 碳酸盐与酸反应给出一个盐、水和二氧化碳:
$$\text{CaCO}_3 + 2\text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2\text{O} + \text{CO}_2$$
第 2 族反应性沿族向下增加,因为原子变得更大
The oxides and hydroxides of Group 2 metals are: · 第 2 族金属的氧化物和氢氧化物是:
They are basic — they react with water and neutralise acids. · 它们是碱性的——它们与水反应并中和酸。
A Group 2 carbonate reacting with a dilute acid produces: · 一个第 2 族碳酸盐与一个稀酸反应产生:
e.g. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂. · 例如 CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂。
You've got it
- Group 2 metals lose two electrons → 2+ ions; reactivity increases down (larger atoms)
- react with oxygen (oxide), water (hydroxide + H₂), acid (salt + H₂)
- oxides/hydroxides are basic; carbonates + acid → salt + water + CO₂
你掌握了
- 第 2 族金属失去两个电子 → 2+ 离子;反应性沿族向下增加(更大的原子)
- 与氧(氧化物)、水(氢氧化物 + H₂)、酸(盐 + H₂)反应
- 氧化物/氢氧化物是碱性;碳酸盐 + 酸 → 盐 + 水 + CO₂