Why salt, sugar and copper behave differently

Answer Key - Grade 10 Science Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Table salt melts at 800.7 °C and sugar at 185.5 °C (CRC). How much higher is salt's melting point, Ari?

   615.2 °C
2. 2.

   Copper melts at 1084.62 °C and table salt at 800.7 °C. How much higher is copper's melting point, Bo?

   283.92 °C

3. Read this first

   Dot diagram beside a property table

   Salt (ions), sugar (shared pairs) and copper (an electron sea) (CRC Handbook via PubChem). Columns: substance, bonding, melting point (°C), conducts as a solid?, conducts melted or dissolved?. table salt, NaCl, ionic, 800.7, no, yes; table sugar, sucrose, covalent molecules, 185.5, no, no; copper, metallic, 1084.62, yes, yes, when melted.

4. 3.

   Using the table, which substance melts at the lowest temperature, Jun?

   • Copper
   • Table sugar
   • Table salt
5. 4.

   Using the table, which conducts electricity as a solid, Kira?

   • Table salt
   • Table sugar
   • Copper
6. 5.

   Using the table, what kind of bonding does table salt have, Luz?

   • Ionic
   • Covalent molecules
   • Metallic
7. 6.

   Why does a copper wire conduct electricity, Milo?

   • Its electrons can move
   • It is shiny and smooth
   • It dissolves
8. 7.

   Why doesn't solid table salt conduct electricity, Noah?

   • Salt contains no ions of any kind
   • Its ions are locked in place
   • It is too soft
9. 8.

   What happens when a salt crystal is struck hard, Ren?

   • It stretches into a wire
   • It bends
   • It shatters
10. 9.

    Why can copper be drawn into thin wire, Tala?

    • Its ions repel each other and crack
    • Its ions slide in the electron sea
    • It is made of molecules
11. 10.

    Why do ionic crystals crack instead of bending, Zee?

    • They are too cold
    • Shifted layers push like charges together
    • They have no bonds