Unit 2: Topic 4 - Structure of Metals and Alloys

Question 1

What are metals and metallic bonding?

Answer 1

Metallic Bonding: Metals have metallic bonding and consist of cations (positively charged ions) and a “sea of electrons”. This means that although the cations are in place, the electrons are constantly moving, not belonging to a single atom (Delocalized).

Properties of metals due to delocalized electrons:
1) Metals can conduct electricity. (It has free movement of electrons and charged molecules, which are needed to conduct electricity).
2) Metals are malleable and ductile.

Malleability: Ability of a material to be hammered into thin sheets.
Ductility: Ability of a material to be drawn into wires.

Question 2

What are interstitial alloys?

Answer 2

Alloys: They are formed when two metals are mixed together. (Physical change)
Interstitial Alloy: This is when the two metals mixed are very different in size. The smaller metal fills in spaces created by the bigger metal called the interstitial spaces.
Ex: Steel (formed by iron and carbon, where carbon is found in the interstitial spaces)

Question 3

What are substitutional alloys?

Answer 3

Substitutional Alloys: This is when two metals with similar sizes are combined. One atom replaces the other.
Ex: Brass (Zinc is substituted for copper)
Alloys are stronger and less malleable than pure metals (only one element) because the addition of another element changes the structure.
Here is a visual.