Materials: Metals and Non-Metals

Physical properties of Metals

1a. Metals can conduct electricity and heat, i.e., they let current and heat pass through it easily.

1b. Application:

Copper is used to make electrical wires. Aluminum is used to make cooking utensils.

2a. Metals are ductile, which means that they can be drawn into wires.

2b. Application:

Copper is used to make wires.

3a. Metals are hard because of the packing of its atoms.

3b. Application:

Iron is used in making buildings.

3c. Exception:

Sodium and potassium are soft and can be cut with a knife.

4a. Metals are lustrous (shiny), which means that they reflect light from their surface and can be polished.

4b. Application:

Metals are used to make jewelry.

4c. Exception: Pure sodium and potassium are not lustrous.

5a. Metals are malleable, which means that they can be beaten into thin sheets.

5b. Application: Silver or aluminum foil to keep food warm.

6a. Most metals remain solid at room temperature.

6b. Application: Metals can be used for many things.

6c. Exception: Mercury and gallium which remain liquid at room temperature.

7a. Metals produce ringing sounds when they are struck and hence, they are sonorous,

7b. Application: Bells are made of metals.

7c. Exception: Mercury is not sonorous at room temperature as it is liquid state.

Physical properties of Non-Metals

1a. Non-Metals cannot conduct electricity and heat, i.e., they do not let current and heat pass through it easily.

1b. Use: Handles of cooking utensils are made of rubber. Resistors are made of non-metals.

1c. Exception: Graphite is a good conductor of electricity.

2a. Non-Metals are brittle, which means on striking they break.

3a. Most non-metals are soft.

3b. Diamond is the hardest material found on Earth

4a. Most non-metals are dull in appearance.

4b. Exception: Diamond is shiny.

5a. Non-metals are easily breakable and hence non-malleable.

6a. Most non-metals exist in two of the three states of matter at room temperature: Gases (such as oxygen), and Solids (such as carbon)

7a. Non-metals do not produce ringing sounds when they are struck.

8. Despite lacking the properties, non-metals are very useful. Some of the applications are:

8a. Essential for life (such as oxygen)

8b. Used as fertilizers (such as nitrogen and phosphorus)

8c. Used to purify water (such as chlorine)

8d. Applied on wounds as an antiseptic (such as purple-colored iodine solution)

8e. Used in crackers (such as sulphur)

Chemical properties of Metals

A. Reaction with Oxygen

When metals react with oxygen, they form metal oxide.

Metal + O₂ → Metal Oxide

Examples:

1. Rusting of Iron

Iron erodes (form a red layer) in presence of oxygen and water thus forming iron oxide.

Iron (Fe) + Oxygen (O₂) + Water (H₂O) → Ferric Hydroxide (Fe(OH)₃)

2. Magnesium burns in oxygen to form magnesium oxide.

Magnesium (Mg) + Oxygen (O₂) → Magnesium Oxide (MgO)

3. Verdigris of copper

When a copper vessel is exposed to moist air for long, it acquires a dull green coating.

Copper (Cu) + Moist Air (Water (H₂O) + Oxygen (O₂) + Carbon Dioxide (CO₂)) → Copper Hydroxide (Cu(OH)₂) + Copper Carbonate (CuCO₃)

4. Basic Nature of Metallic Oxides

A. Reaction with Air

When ashes of magnesium, after burning in air, is dissolves in water, it changes red litmus to blue. Thus, it is basic in nature.

In general, metallic oxides are basic in nature.

B. Reaction with Water

Some metals react with water to form metal hydroxide and hydrogen gas.

Metal + (cold) Water → Metal hydroxide + Hydrogen

Metal + Stream → Metal oxide + Hydrogen

Examples:

1. Sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated in the reaction. It is, therefore, stored in kerosene.

Sodium (Na) + Water (H₂O) → Sodium Hydroxide (NaOH) + Hydrogen (H₂)+ Heat

2. Metal hydroxides are basic in nature and turn red litmus to blue.

C. Reaction with Acid

Some metals react with acid to form metal salts and hydrogen gas.

Metal + Acid → Metal Salt + Hydrogen

Examples:

1. Reaction of Magnesium with HCl

Magnesium (Mg) + Hydrochloric Acid (HCl) → Magnesium Chloride (MgCl₂) + Hydrogen (H₂)

2. Reaction of Aluminum with HCl

Aluminum (Al) + Hydrochloric Acid (HCl) →Aluminum Chloride (AlCl₃) + Hydrogen (H₂)

3. Reaction of Iron with HCl

Iron does not react with hydrochloric acid at room temperature, however it reacts when heated.

Iron (Fe) + Hydrochloric Acid (HCl) →Iron Chloride (FeCl2) + Hydrogen (H2)

4. Copper does not react with hydrochloric acid at room temperature, and even on heating. However it reacts with H₂SO_4. (Sulfuric Acid)

Copper (Cu) + Sulfuric Acid ( H₂SO₄) → Copper Sulfate (CuSO₄ ) + Sulfur dioxide (SO₂)+ Water (H₂O)

5. Presence of hydrogen gas is detected by a ‘pop’ sound.

D. Reaction with Base

Some metals react with acid to form metal salts and hydrogen gas.

Metal + Acid → Metal Salt + Hydrogen

Examples:

1. Reaction of Aluminum with Sodium Hydroxide

Aluminum (Al) + Sodium Hydroxide (NaOH) + Water (H₂O)→Sodium Aluminate (NaAlO₂) + Hydrogen (H₂)

2. Presence of hydrogen gas is detected by a ‘pop’ sound.

E. Reaction of Metals with Solutions of Other Metal Salts

Metal A + Salt Solution of Metal B → Salt Solution of Metal A + Metal B

1. More reactive metals replaces less reactive metals.

2. Less reactive metals cannot replace more reactive metals.

3. The order of reactivity of metals is:

Potassium > Sodium > Calcium > Magnesium > Aluminum > Zinc >Iron > Lead > Copper > Silver > Gold

4. This is called a displacement reaction.

Examples:

1. Reaction of Copper Sulphate and Iron

Iron (Fe )+ Copper Sulfate ( CuSO₄) → Iron Sulfate ( FeSO₄) + Copper (Cu)

2. Reaction of Copper Sulphate and Zinc

Copper Sulphate (CuSO₄) + Zinc (Zn) → Zinc Sulphate + Copper (Cu)

3. Iron + Zinc Sulfate → No reaction

4. Copper + Zinc Sulfate → No reaction

5. Copper + Iron Sulfate → No reaction

Chemical Properties of Non-Metals

A. Reaction with Oxygen

When non-metals react with oxygen, they form metal oxide.

Non-Metal + O₂ → Non-Metal Oxide

Example:

1. Reaction of Sulphur with Oxygen

Sulphur (S) + Oxygen (O₂) → Sulphur dioxide (SO₂)

2. The ashes of sulphur on mixing with water turns blue litmus red, thus indicating their acidic nature.

In general, non-metallic oxides are acidic in nature.

Sulphur dioxide (SO₂) + Water (H₂O) →Sulphurous acid (H₂SO₃)

B. Reaction with Water

1. Non-metals do not react with water.

2. Phosphorus is a very reactive non-metal. It catches fire if exposed to air. To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water.

C. Reaction with Acids

1. Non-metals generally do not react with acid.

2. Example: Charcoal reacts with concentrated sulphuric acid

Charcoal (C) +conc. Sulphuric Acid (H₂SO₄) → Carbon Dioxide (CO₂) + Sulphur Dioxide (SO₂) + Water (H₂O)

D. Reaction with Bases

1. Reaction of non-metals with bases are complex.

Summary