Question

properties of atoms and compounds
1 can be solids, liquids or gases at room temperature
2 conduct electricity when molten
3 low melting and boiling points
4 usually soluble in water
5 soft and malleable
6 hard and brittle
7 usually solid at room temperature
8 does not conduct electricity when molten

1. identify the properties listed above that are characteristic of ionic compounds:

fill in the numbers below:
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Explanation:

Step1: Recall ionic compound properties

Ionic compounds: conduct electricity molten (ions mobile), usually solid at room temp, hard & brittle, usually soluble in water, high melting/boiling (wait, no—wait, ionic: high melting/boiling? Wait, no, wait. Wait, ionic compounds:

• Conduct electricity when molten (ions free to move) → property 2.
• Usually solid at room temp (ions in lattice) → property 7.
• Hard and brittle (ionic lattice breaks under stress) → property 6.
• Usually soluble in water (ions dissociate) → property 4.

Wait, wait, initial thought: ionic compounds have high melting/boiling, so property 3 (low) is covalent. Property 1: covalent can be all states, ionic usually solid. Property 5: soft/malleable is metallic. Property 8: non-conducting molten is covalent. So ionic properties: 2 (conduct molten), 4 (soluble in water), 6 (hard brittle), 7 (usually solid). Wait, let's recheck:

Ionic compound properties:

• State: usually solid at room temp (so 7).
• Conductivity: conduct when molten (ions mobile) → 2.
• Solubility: usually soluble in water (ions dissociate) → 4.
• Hardness: hard and brittle (ionic lattice, breaking causes ion repulsion) → 6.
• Melting/boiling: high (so property 3 is low, covalent). Property 1: covalent can be solid/liquid/gas, ionic usually solid. Property 5: soft/malleable is metal. Property 8: non-conducting molten is covalent (molecular, no ions). So the ionic properties are 2,4,6,7.

Step2: List the numbers

So the numbers are 2,4,6,7.

Answer:

2, 4, 6, 7