Unit 1 Planet Earth and The Microscopic World and Metal (微觀世界+金屬)
1. The most abundant element in the world is oxygen and the most abundant metal in the world is aluminium
地球上最豐富的元素是氧，最豐富的金屬是鋁
2. The chemical nature of lime water is Ca(OH)2
石灰水的化學本質是Ca(OH)2
3. Flame test is not a test for metal but metal ion. For example, golden yellow flame can be observed when NaCl is burning. When sodium is burning, metal Na turn to Na2O and Na+in Na2O give golden yellow color
焰色測試是測試金屬離子而不是金屬，例如燃燒 NaCl，可以看見金黃色火焰。燃燒Na 時，金屬Na 轉為Na2O，Na2O裡的Na+ 把火焰轉為黃色
4. The "molar mass" of air is around 29 g mol-1 which can be obtain by following formula
molar mass of air = N2 x 78% + O2x 21% = 28.56 g mol-1
If the molar mass of a gas is smaller than air, it density is lower than air and we should use an suitable method to collect the gas.
空氣的「摩爾質量數」大約是 29 g mol-1，是這樣計算出來的
空氣的「摩爾質量數」 = N2 x 78% + O2 x 21%
= 28.56 g mol-1
如果某種氣體的摩爾質量數比空氣細，它的密度比空氣低，知道這點有助我們選取適合的氣體收集方法。
(Others coming soon =) )
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