The question
Name: ______________________ Date: ____________ Ionic oxides and a hardened metal (4 points)
Data table
Two oxides and a metal
A materials lab compares two ionic oxides and a metal used to make a cutting tool.
| Substance | Ions or atoms (radius, pm) | Melts at (°C) |
|---|---|---|
| SrO | Sr²⁺ (118), O²⁻ (140) | 2531 |
| BaO | Ba²⁺ (135), O²⁻ (140) | 1923 |
| Iron, Fe | Fe atom (126) | 1538 |
(a) Explain why SrO melts at a higher temperature than BaO. Your answer should refer to both compounds. [1 point]
(b) Solid SrO does not conduct electricity, but molten SrO does. Explain this difference in terms of the particles present. [1 point]
(c) A small amount of carbon (atomic radius 77 pm) is added to iron to make steel. In the box, draw a particle diagram of steel showing at least 12 iron atoms and a few carbon atoms. Include a key. [1 point]
(d) Steel is harder and less malleable than pure iron. Explain why, using your diagram from part (c). [1 point]