Atoms and Ions: A Reactivity Series for Metals

An atom is the smallest particle of an element that can exist either alone or in combination while an ion is an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
Metals form positive ions when they lose electrons. For example, Magnesium (Mg) loses two electrons to form Mg²⁺.
The number of outer shell electrons in a metal atom influences its reactivity. Metals with more outer shell electrons are less reactive, because it’s harder for them to lose electrons and form positive ions.
The reactivity series is a list of metals ranked in order of decreasing reactivity. At the top of the series are the most reactive metals and at the bottom, the least reactive.
An example of a standard metal reactivity series from most to least reactive would be Potassium (K), Sodium (Na), Lithium (Li), Calcium (Ca), Magnesium (Mg), Aluminium (Al), Zinc (Zn), Iron (Fe), Copper (Cu), Silver (Ag), and Gold (Au).
Displacement reactions help determine the reactivity series for metals. In a displacement reaction, a more reactive metal will displace a less reactive metal from its salt solution. For instance, if copper is put in a solution of silver nitrate, nothing happens because copper is less reactive than silver. However, if zinc is put in a solution of copper sulphate, zinc displaces copper from the solution as it is more reactive.
The reactivity series can help predict how a metal will react with oxygen (in the air) and acids. Metals that come lower in the series are less likely to react whereas those higher up will readily interact.
Oxidation is a chemical reaction where a substance loses electrons. This usually occurs when metals react with oxygen to form metal oxides. Metals that oxidize rapidly are higher in the reactivity series.
Aqueous metal ions can be reduced (gain electrons) using different reducing agents. The ease of this reduction can also indicate the reactivity of the metal.
In general, understanding the reactivity series for metals is crucial as it enables predictions about the products of reaction and helps evaluate potential risks and benefits of reactions involving these metals.

Remember to undertake plenty of practice questions and experiments related to these points to strengthen the understanding and application of the concepts.