Write the names and symbols of two most reactive metals belonging to group I of the periodic table. Explain by drawing electronic structure how either one of the two metals reacts with a halogen. With which name is the bond formed between these elements known and what is the class of the compound so formed known ? State any four physical properties of such compounds. Or What is meant by refining of a metals ? Name the most widely used method of refining impure metals produced by various reduction processes. Describe with the help of a labelled diagram how this method may be used for refining of copper.

Option 1: Group I Metals and Ionic Compounds

#### 1. Two Most Reactive Group I Metals

• Sodium (Symbol: $Na$)
• Potassium (Symbol: $K$)

#### 2. Electronic Structure and Reaction with a Halogen (Chlorine)

• Sodium ($Na$) has atomic number 11 and electronic configuration $2, 8, 1$. It has 1 valence electron.
• Chlorine ($Cl$) has atomic number 17 and electronic configuration $2, 8, 7$. It has 7 valence electrons.
• Reaction Mechanism:

Sodium loses its single valence electron to form a stable sodium cation ($Na^+$):

$$Na \rightarrow Na^+ + e^-$$

$$(2, 8, 1) \rightarrow (2, 8)$$

Chlorine gains this electron to complete its octet and form a stable chloride anion ($Cl^-$):

$$Cl + e^- \rightarrow Cl^-$$

$$(2, 8, 7) \rightarrow (2, 8, 8)$$

The electrostatic attraction between the oppositely charged ions binds them together to form Sodium Chloride ($NaCl$):

$$Na^+ + Cl^- \rightarrow NaCl$$

#### 3. Bond Name and Class of Compound

• Bond Name: Ionic bond (or Electrovalent bond)
• Class of Compound: Ionic compounds (or Electrovalent compounds)

#### 4. Four Physical Properties of Ionic Compounds

1. Physical Nature: They are crystalline solids and are generally hard and brittle due to strong electrostatic forces of attraction between ions.
2. High Melting and Boiling Points: They have high melting and boiling points because a large amount of energy is required to break the strong inter-ionic forces.
3. Solubility: They are generally soluble in water but insoluble in organic solvents like kerosene and petrol.
4. Electrical Conductivity: They do not conduct electricity in the solid state (as ions are held in fixed positions), but they conduct electricity in molten state or aqueous solution where ions are free to move.

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Option 2 (OR): Refining of Metals

#### 1. Definition of Refining

Refining is the process of purifying crude or impure metals obtained from various reduction processes to get highly pure metal.

#### 2. Most Widely Used Method

Electrolytic Refining is the most widely used method for refining impure metals.

#### 3. Electrolytic Refining of Copper

• Anode: A thick block of impure copper.
• Cathode: A thin strip of pure copper.
• Electrolyte: Acidified copper sulphate ($CuSO_4$) solution.
• Working Process:

When electric current is passed through the electrolyte, pure copper from the anode dissolves into the electrolyte as $Cu^{2+}$ ions:

$$\text{At Anode (Oxidation): } Cu(s) \rightarrow Cu^{2+}(aq) + 2e^-$$

An equivalent amount of pure copper from the electrolyte is deposited on the cathode:

$$\text{At Cathode (Reduction): } Cu^{2+}(aq) + 2e^- \rightarrow Cu(s)$$

The soluble impurities go into the solution, while the insoluble impurities settle down at the bottom of the anode as anode mud.