# Alloys: definition and preparation

> Two metals or more, or a metal with a non-metal; made by melting or by electro-deposition


## Objectives

- State the book's definition of an alloy, with metal-metal and metal-non-metal examples.
- Describe preparation by melting: melt the metals together, then leave them to cool gradually.
- Describe preparation by electro-deposition of two or more metals at the same time.
- Recognize that an alloy may contain a non-metal and is not always a chemical compound.

## 1. Alloys and their types




## 2. Metals only?

Predict: which one contains a non-metal?

- Both
- Neither: alloys contain metals only
- Steel ✓
- Ferromanganese

Steel contains a non-metal: it is iron with carbon, and it is still an alloy. Ferromanganese is iron with manganese, two metals.

[ar-EG] الـ steel هو اللي فيه non-metal: هو iron مع carbon، ومع كده هو alloy. أما الـ ferromanganese فهو iron مع manganese، يعني اتنين metals.
## 3. What an alloy is

Alloy Alloys are usually formed from two metals or more, and may consist of a metal and a non-metal, such as carbon (steel). The book's examples (p.19). Ferro- means iron. So an alloy is not always metals only: steel contains carbon. Alloys you met in the uses lessons Ferromanganese: railway tracks, because it is harder than steel. Nickel-chromium: heating coils and electric furnaces. Aluminum-manganese: soft drink cans. Bronze: copper with tin.


## 4. Not always a compound

Every alloy is a chemical compound. Here, atoms of two metals share one solid. No new compound forms.


## 5. Method 1: by melting

Preparation by melting (p.19) Alloys are usually prepared by melting the metals together and leaving them to cool gradually. The metals mix while they are liquid.


## 6. Method 2: by electro-deposition

Electro-deposition Depositing two metals or more at the same time from a solution of their ions, using an electric current. Kinds of metal ions in the solution Copper ions only: a copper coat. One metal is not an alloy. Copper and zinc ions deposit at the same time: a brass coat (Cu + Zn), an alloy. Book example: electroplating iron handles with brass, from a solution of copper and zinc ions.


## 7. Sort the methods

Decide how each one is made. Careful: some are not alloys at all. How is each product made?


## 8. Check yourself

Metal X is mixed with a little of non-metal Y in one solid. A student says: "Y is a non-metal, so this cannot be an alloy." Is the student right?

- Yes: alloys contain metals only
- Yes: a metal and a non-metal always form a compound
- No: an alloy may consist of a metal and a non-metal ✓

An alloy may consist of a metal and a non-metal, so a non-metal in it does not rule out an alloy. Steel, iron with carbon, is the book's example.

[ar-EG] الـ alloy ممكن يتكوّن من metal و non-metal، فوجود non-metal فيه مايمنعش إنه يبقى alloy. ومثال الكتاب هو الـ steel: iron مع carbon.
## 9. Summary

Alloy: usually two metals or more, or a metal with a non-metal (steel). By melting: melt the metals together, then leave them to cool gradually. By electro-deposition: two metals or more deposit at the same time. An alloy is not always a compound. Exams ask for the two methods of preparing alloys. Answer: by melting, and by electro-deposition (brass on iron handles). Back to the hook: can you explain why steel is an alloy, though carbon is not a metal? Steel is iron with carbon. An alloy is usually formed from two metals or more, but it may consist of a metal and a non-metal, such as carbon in steel.



Chapter: Transition Elements (https://yaani.ai/ar/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/ar/lesson/chem-s3-en.lesson-alloy.definition-preparation