Solid structures Flashcards
What is a simple covalent structure?
Strong intramolecular covalent bonds but weak intermolecular forces. Little energy required to break bonds which leads to a low melting point.
Give examples of a simple covalent structure
Iodine and carbonmonoxide.
What is a giant covalent structure?
A repeating lattice of strong covalent bonds, leading to a high melting point.
Give examples of giant covalent structure
Diamond- four strong tetrahedral covalent bonds per carbon, forming a cross linked structure, insulator
Graphite- three strong covalent bonds per carbon, hexagonal planes with weak Van der Waals forces between layers, conductor
What is a giant ionic structure?
Repeating lattice of oppositely charged ions. Strong electrostatic attraction between ions create a high melting point. Higher ionic charge, greater force of attraction. Only conducts when molten as ions are free to move, brittle as ions repel.
Give examples of giant ionic structures
Caesium chloride (8,8)- body centre cubic
Sodium chloride (6,6)- face centre cubic
What is the crystal co-ordination number?
The number of anions around each cation in an ionic lattice and vice versa.
Explain metallic structure
The atoms of metallic elements each donate one or more electrons to form a delocalised electron sea or gas that surrounds the packed positive ions and binds them together through the attraction between opposite charges.
What is the difference between a giant molecule and a simple molecular structure?
Giant- a molecule with a large number of bonded atoms
Simple- A molecule having not many bonded atoms
What are the trends in solubility in water for solid structures?
Many giant ionic molecules are soluble while giant covalent molecules are insoluble.
How are metals malleable and ductile?
As their arrangement gives good flexibility since there are no fixed bond angles.
Give general properties of metals
Good thermal and electrical conductors
Ductile and malleable
Hard and shiny
Name a new form of carbon that is becoming important and outline its structure
Graphene comprises of single layers of graphite-type hexagons and has exceptional strength among other properties.
