Metal Reactivity with Oxygen and Water

• Metals exhibit varying degrees of reactivity with oxygen, water, acids, and bases, influencing their behavior in different environments
• The reactivity series of metals arranges metals in order of their decreasing reactivity, helping predict their reactions.

Reactivity with Oxygen

• Metals react with oxygen to form metal oxides
• The rate and extent of this reaction vary greatly depending on the metal.
• Highly reactive metals like potassium (K) and sodium (Na) react vigorously with oxygen at room temperature, forming oxides rapidly.
• Magnesium (Mg) reacts with oxygen upon heating, producing bright light and heat and forming magnesium oxide (MgO).
• Iron (Fe) reacts slowly with oxygen in the presence of moisture to form iron oxide (rust) (Fe2O3).
• Gold (Au) and platinum (Pt) are unreactive with oxygen, even at high temperatures, which explains their use in jewelry and other applications where corrosion resistance is required

Reactivity with Water

• Metals react with water to form metal hydroxides and hydrogen gas
• The reactivity of metals with water varies significantly.
• Alkali metals such as lithium (Li), sodium (Na), and potassium (K) react vigorously with cold water, forming metal hydroxides and hydrogen gas.
• The reaction is exothermic, and the heat generated can ignite the hydrogen gas, leading to a fire or explosion.
• Magnesium (Mg) reacts slowly with cold water but reacts readily with steam to form magnesium oxide and hydrogen gas.
• Zinc (Zn), iron (Fe), and tin (Sn) do not react with cold water but react with steam at high temperatures to form metal oxides and hydrogen gas.
• Copper (Cu), silver (Ag), and gold (Au) do not react with water or steam, even at high temperatures

Reactivity with Acids

• Metals react with acids to form metal salts and hydrogen gas
• The reaction rate depends on the metal's position in the reactivity series and the concentration and strength of the acid.
• Reactive metals like potassium (K), sodium (Na), and calcium (Ca) react violently with dilute acids, such as hydrochloric acid (HCl) and sulfuric acid (H2SO4), producing metal salts and hydrogen gas.
• Magnesium (Mg), aluminum (Al), and zinc (Zn) react readily with dilute acids, forming metal salts and hydrogen gas.
• Iron (Fe) reacts slowly with dilute acids, forming iron salts and hydrogen gas.
• Copper (Cu) reacts with concentrated nitric acid (HNO3) and hot concentrated sulfuric acid (H2SO4) to form metal salts, water, and oxides of nitrogen or sulfur, respectively, instead of hydrogen gas.
• Silver (Ag) reacts with nitric acid (HNO3)
• Gold (Au) and platinum (Pt) do not react with most acids, including hydrochloric acid (HCl) and sulfuric acid (H2SO4).

Reactivity with Bases

• Some metals react with strong bases to form complex ions and hydrogen gas
• The reaction is more complex than with acids and is limited to a few metals.
• Aluminum (Al) reacts with strong bases like sodium hydroxide (NaOH) and potassium hydroxide (KOH) to form complex ions called aluminates and hydrogen gas.
• Zinc (Zn) reacts with strong bases like sodium hydroxide (NaOH) and potassium hydroxide (KOH) to form complex ions called zincates and hydrogen gas.
• Tin (Sn) reacts with strong bases like sodium hydroxide (NaOH) and potassium hydroxide (KOH) to form complex ions called stannates and hydrogen gas.
• Other metals, such as iron (Fe), copper (Cu), and silver (Ag), do not react with bases.

Factors Affecting Reactivity

• Electronic Configuration: Metals with loosely held valence electrons tend to be more reactive as they readily lose electrons to form positive ions
• Ionization Energy: Metals with low ionization energies are more reactive because they require less energy to lose electrons
• Atomic Size: Larger atomic size generally corresponds to higher reactivity since the valence electrons are further from the nucleus and easier to remove
• Metallic Bonding: Metals with weaker metallic bonds are generally more reactive as less energy is required to break the bonds during a reaction
• Surface Conditions: The presence of oxide layers or impurities on the metal surface can affect its reactivity:

Displacement Reactions

• A more reactive metal can displace a less reactive metal from its salt solution
• This principle is used in various industrial processes, such as the extraction of metals from their ores.
• For example, zinc (Zn) is more reactive than copper (Cu), so when zinc metal is added to a solution of copper sulfate (CuSO4), zinc displaces copper from the solution, forming zinc sulfate (ZnSO4) and depositing copper metal.

Explore how metals react with oxygen and water, forming oxides and other compounds. Understand the reactivity series, which ranks metals by their reactivity. Learn about the varying rates and extents of these reactions, and how they determine metals' applications.