Chemistry-only: transition metals compared with Group 1
도입됨| English | 의미 |
|---|---|
| transition metal/trænˈsɪʃn ˈmetl/ | 전이 금속 |
| density/ˈdensɪti/ | 밀도 |
What would explain this observation?
- A copper wire and a piece of sodium are both metals, yet their behaviour in water and their usefulness in construction differ substantially. Being a metal does not imply Group 1 reactivity.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- The specified transition examples are Cr chromium, Mn manganese, Fe iron, Co cobalt, Ni nickel and Cu copper. Compared with Group 1 metals, these typically have higher melting points and densities and are stronger and harder. They are generally less reactive with oxygen, water and halogens. Sodium is soft enough to cut and reacts vigorously with cold water; an iron nail does not show that Group 1 reaction.
- transition metal 过渡金属: A metal from the central transition region exemplified here by Cr, Mn, Fe, Co, Ni and Cu; density 密度: Mass per unit volume of a substance.
Which comparison is typical for the specified transition metals versus Group 1?
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
Compared with Group 1, the specified transition metals are denser, harder and higher-melting, and react only slowly - iron rusts over days where sodium fizzes in seconds. A more vigorous water reaction and lower hardness describe Group 1, not them.
Match each technical term to its precise meaning.
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Iron can react with steam under suitable conditions and can rust slowly in oxygen and water; copper does not react with cold water in the Group 1 manner. Many transition metals react with oxygen or halogens when heated, so less reactive does not mean incapable of reaction. Compare the same conditions and specify whether an observation is rapid burning, slow corrosion or no visible change.
- Use supplied property data and teacher-approved solid samples to compare density and qualitative hardness. Avoid student handling of alkali metals. Rank measured values rather than extrapolating an exact value for every transition element. For reaction comparisons, teacher demonstrations or source observations must have stated conditions and comparable sample sizes.
Which two habits make the investigation or model in this case more defensible?
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: supplied rounded densities are sodium 0.97 and iron 7.9 g/cm³. Equal volumes have mass ratio iron/sodium = 7.9/0.97 ≈ 8.14. A 2.0 cm³ iron model sample has mass 7.9×2.0=15.8 g. Density does not itself measure reaction rate, hardness or strength.
A supplied metal density is 8.0 g/cm³ and its volume 3.0 cm³. Calculate its mass. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A supplied metal density is 8.0 g/cm³ and its volume 3.0 cm³. Calculate its mass.
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
The result is 24 g. Known: density 8.0 g/cm^3; volume 3.0 cm^3. Use mass = density x volume. Mass = 8.0 x 3.0 = 24 g. Density links mass and volume; it measures neither hardness nor reactivity.
Check the conclusion and its limits
- The listed differences are typical comparisons, not universal laws for every metal. Density and hardness name different properties. Transition metals can react with halogens, and lack of an immediate cold-water reaction does not prove no reaction under different conditions.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Transition metals never react with oxygen or halogens. This claim is false: Iron reacts with oxygen (rusting) and chlorine (forming iron chlorides); transition metals are less reactive than Group 1, not inert. Speed of reaction, not its existence, is the difference.
Chemistry-only: transition metals compared with Group 1: Iron can react with steam under suitable conditions and can rust slowly in oxygen and water; copper does not react with cold water in the Group 1 manner. Many transition metals react with oxygen or halogens when heated, so less reactive does not mean incapable of reaction. Compare the same conditions and specify whether an observation is rapid burning, slow corrosion or no visible change.
Transition metals never react with oxygen or halogens.
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
Iron reacts with oxygen (rusting) and chlorine (forming iron chlorides); transition metals are less reactive than Group 1, not inert. Speed of reaction, not its existence, is the difference.
A metal from the central transition region exemplified here by Cr, Mn, Fe, Co, Ni and Cu: write the technical term.
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
transition metal means A metal from the central transition region exemplified here by Cr, Mn, Fe, Co, Ni and Cu.