metal

Fe 係一隻metal, not ion
佢rusting 姐係甩electron，Fe-> Fe2+ +2e-
所以應該係release electron.
所以句statement唔岩
但less reactive substance係tends to absorb electron, 但唔係用黎解釋rusting

咁點解佢甩electron?
because it reacts with water, oxygen to give iron(II) ion. or further 3+ ion (Reason of rusting)
increase the rate of rusting can add electrolyte(NaCl).(factor of increasing the rate of rusting)

其實你問的問題本來就比較含糊。
你是說, 有一較不活躍的金屬貼在鐵上會令鐵更易生鏽嗎?
那就是在問sacrificial protection的問題了。

從最開始說起的話, 金屬由於其電子雲的結構, 因此在反應時通常傾向於釋放電子。因此less reactive metal, 通常是指比較不願釋放電子的金屬。比較不願釋放電子, 也就表示它電荷上比較正(縱使它總電荷是零)。
當一塊比較正的金屬貼在鐵的時候, 由於它們是giant metallic structure, 電子可自由移動, 電子就傾向由less reactive metal走向iron, 令iron產生了partial negative charge, 更傾向於釋放電子, 也就更易生鏽了。

Brian, Stainless steel 站在你背後, 他看起來很火...

好吧, 我晚一點再回答.

2012-11-07 23:04:58 補充：
Nickel and chromium may be less reactive than iron, but they retard rusting as in stainless steel. When their content esp. Cr is high enough, a firm and tough Cr-oxide layer forms on steel surface, retarding rusting.

2012-11-07 23:06:03 補充：
In this case, Cr retards rusting NOT because it's less reactive than iron, but because it can form a tough and firm oxide layer on surface, avoiding surface to come further contact with air.

Rust is the term specially for oxidization of iron . Like copper is a less reactive metal which donot rust but also can be oxidized . Usally in rusting , iron will lose electrons , with the presence of oxygen & water to form rust . With the presnce of less reactive metals , like stainless steel which is an alloy of iron with carbon , nickel , chronium & etc., is less likely to form rust . Also with zinc plated iron (galvanized iron) is also less likely to get rust . The above examples are iron with less reactive or more reactive metals , do retard rust happened . So what you ask I donot understand , please state what metals would increase the rate of rusting . What I know NaCl solution will increase the rate of rust . This is due to the presence of chloride ions . If in the water there are metallic salts , the presnce of metal ions might increase the rate of rusting this is because the iron will more easily become an iron ion .