Chemical Changes and Reactions
Ever wondered why some metals rust faster than others? The reactivity series is like a league table that ranks metals from most reactive (potassium at the top) to least reactive (platinum at the bottom). This ranking determines which metals can displace others in chemical reactions - more reactive metals will always kick out less reactive ones from their compounds.
When acids react with metals, they follow predictable patterns that you absolutely need to memorise for your exams. Metal + acid always produces a metal salt + hydrogen gas, whilst metal oxide + acid gives you a metal salt + water. These reactions are called redox reactions because oxidation (losing electrons) and reduction (gaining electrons) happen simultaneously.
The pH scale runs from 1-14 and shows how acidic or alkaline a solution is. Strong acids like hydrochloric acid completely break apart in water to release H+ ions, whilst weak acids like vinegar only partially dissociate. Remember: acids produce H+ ions, alkalis produce OH- ions, and neutral solutions sit at pH 7.
Quick Tip: Use the mnemonic "OIL RIG" - Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons) - to remember redox reactions!
Electrolysis uses electricity to split up ionic compounds, which is how we extract reactive metals like aluminium from their ores. The process needs two electrodes: the positive anode (where oxidation occurs) and the negative cathode (where reduction happens). This technique is essential for manufacturing many of the metals we use daily, from the aluminium in your drinks cans to the copper in electrical wires.
