- Metallic bonds are very strong and are a result of the attraction between the positive metal ions and the negative delocalised electrons within the metal lattice structure
- Metals thus have very high melting and boiling points and are solids at room temperature, with the exception of mercury which is a liquid
- They are usually insoluble in water although some do react with it
- Metals are good conductors of heat and electricity due to the delocalised electrons
- The layers of atoms in metals can slide over each other meaning metals are malleable and can be hammered and bent into shapes or rolled into flat sheets
Diagram showing metallic lattice structure with delocalised electrons
The properties of metals can be modified, sometimes significantly, by mixing it with another metal or non-metal to create and alloy.
- Alloys are mixtures of metals, where the metals are mixed together physically but are not chemically combined
- They can also be made from metals mixed with nonmetals such as carbon
- Alloys often have properties that can be very different to the metals they contain, for example they can have greater strength, hardness or resistance to corrosion or extreme temperatures
- Alloys contain atoms of different sizes, which distorts the regular arrangements of atoms
- This makes it more difficult for the layers to slide over each other, so they are usually much harder than the pure metal
- Brass is a common example of an alloy which contains 70% copper and 30% zinc
Particle diagram showing a mixture of elements in an alloy. The different sizes of the two types of atoms prevent the layers of atoms from sliding over each other, so the alloy becomes less malleable than the pure metal
Questions on this topic often give you a selection of particle diagrams and ask you to choose the one which represents an alloy. It will be the diagram with uneven sized particles and distorted layers or rows of particles.