What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.
What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.
Solution and Explanation
An alloy is a solid solution of two or more elements in a metallic matrix. It can either be a partial solid solution or a complete solid solution. Alloys are usually found to possess different physical properties than those of the component elements.
An important alloy of lanthanoids is Mischmetal. It contains lanthanoids (94-95%), iron (5%), and traces of S, C, Si, Ca, and Al.
Uses
(1) Mischmetal is used in cigarettes and gas lighters.
(2) It is used in flame throwing tanks.
(3) It is used in tracer bullets and shells.
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- Statement-I : Consider the following pairs of ions $(\text{Sc}^{3+}, \text{Ti}^{3+}), (\text{Ti}^{4+}, \text{Ni}^{2+}), (\text{Cu}^{2+}, \text{Zn}^{2+})$ and $(\text{Cr}^{3+}, \text{Mn}^{3+})$. Out of these pairs three pairs consist of ions that are both coloured :
Statement-II : Among the lanthanide ions $\text{Eu}^{2+}$, $\text{Gd}^{3+}$, $\text{Ce}^{4+}$ and $\text{Tb}^{4+}$, the ion $\text{Tb}^{4+}$ is the strongest reducing agent.
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Concepts Used:
Lanthanoids
Lanthanoids are at the top of these two-row, while actinoids are at the bottom row.
Properties of Lanthanoids
Lanthanoids are inclusive of 14 elements, with atomic numbers 58-71:
- Cerium - Xe 4f1 5d1 6s2
- Praseodymium - Xe 4f3 6s2
- Neodymium - Xe 4f4 6s2
- Promethium - Xe 4f5 6s2
- Samarium - Xe 4f6 6s2
- Europium - Xe 4f7 6s2
- Gadolinium - Xe 4f7 5d1 6s2
- Terbium - Xe 4f9 6s2
- Dysprosium - Xe 4f10 6s2
- Holmium - Xe 4f11 6s2
- Erbium - Xe 4f12 6s2
- Thulium - Xe 4f13 6s2
- Ytterbium - Xe 4f14 6s2
- Lutetium - Xe 4f14 5d1 6s2
These elements are also called rare earth elements. They are found naturally on the earth, and they're all radioactively stable except promethium, which is radioactive. A trend is one of the interesting properties of the lanthanoid elements, called lanthanide contraction.