An element X with atomic number 12 combines with an element Y with atomic number 17 to for… — JAMB UTME

An element $X$ with atomic number $12$ combines with an element $Y$ with atomic number $17$ to form a solid compound. Which of the following statements correctly accounts for the electrical conductivity of this compound?

It conducts electricity in the molten state because the giant ionic lattice breaks down, allowing the ions to move freely.Answer
B
It conducts electricity in the solid state because delocalized valence electrons migrate freely through the crystal lattice.
C
It does not conduct electricity when dissolved in water because polar solvent molecules neutralize ionic charges.
D
It conducts electricity in the solid state because covalent electron sharing forms continuous conductive pathways.

Answer

The compound conducts electricity in the molten state because the giant ionic lattice breaks down, allowing the ions to move freely.

In solid electrovalent compounds, ions are locked into fixed lattice coordinates by strong electrostatic attraction and cannot migrate. Heating the compound until it melts breaks down the lattice, liberating the cations and anions so they can move freely under an applied electrical potential.

Step-by-Step Solution

Determine the type of bonding present in the compound formed by

X

and

Y

Element

X

(atomic number 12) has an electronic configuration of

2,8,2

(metal). Element

Y

(atomic number 17) has an electronic configuration of

2,8,7

(non-metal). Metal

X

transfers 2 electrons to two atoms of non-metal

Y

, forming an electrovalent (ionic) compound

XY_2

consisting of

X^{2+}

and

Y^-

ions.

Electrovalent bonding occurs between electropositive metals and electronegative non-metals via full electron transfer.

Evaluate the state of charge carriers in the solid state versus the molten state.

In the solid state, strong electrostatic forces hold

X^{2+}

and

Y^-

ions in rigid, fixed lattice positions, so no charge carriers can move. In the molten state, heat breaks the lattice, enabling the ions to move freely toward oppositely charged electrodes.

Electrical conduction requires mobile charge carriers. In ionic substances, these carriers are mobile ions present only in liquid (molten) or aqueous states.

Key Concept

Ionic bonding and electrical conductivity of ionic compounds

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