Metallic Bonding Flashcards
What is metallic bonding?
The electrostatic forces of attraction between each positive metal ion and the sea of delocalised electrons.
What type of structure does a metal have?
Rigid regular giant structures. There are no individual molecules and all the positive ions in the lattice attract the delocalised electrons.
Delocalised electrons
For example sodium is a metal. When sodium atoms bond together form a solid metal, the outer electron on each sodium atom becomes free to move throughout the whole structure. The electrons are said to be delocalised. They are no longer attached to particular atoms but they are free.
The more outer electrons there are in each atom…
The stronger the bonding will be
Properties of metals
Metals have a high melting and boiling point due to the very strong electrostatic forces of attraction between the positive metal ions and the sea of delocalised electrons.
Good conductors of heat and electricity because the delocalised electrons are free to move throughout the structure.
They are malleable as the sea of delocalised electrons allows the lattice to distort so that the atoms can move past one another.
Metals are described as ductile as they can be drawn into wires. This is because the layers of atoms in a metal can slide easily over each other.
What are alloys?
Alloys are a mixture of metals. They are harder than pure metals because the different metal atoms have different sizes which distort the layers and resist them moving over each other.
Brass - contains copper and zinc. You use it for musical instruments, water taps, ornamental objects etc
Stainless steel - contains chromium and iron. You can use it for culinary, surgical tools etc
Cupronickel - contains copper and nickel. You can use for marine applicants, silver coins etc
Bronze - contain a mix of copper and tin. Is used to make ship’s propellers, castings (statues) etc
