Structure and Bonding Flashcards
How are elements arranged in the periodic table?
In order of increasing atomic number
How are groups arranged in the periodic table?
They are arranged in the same groupn because of simmilar reactivities, caused by the common number of outer electrons.
What is metallic bonding?
Occurs when electrons of metal ions become delocalised, so now positive metal ions are surrounded by a pool of delocalised electrons. This attraction between the charged metal ions and the electrons in known as metallic bonding. These delocalised electrons allow the metal to conduct. More ions and more electrons means stonger metallic bonding.
Covalent Molecular Structures
Three examples are : Phosphorus, Sulphur and Fullerenes (also included diatomic molecules). Shared pair of electrons attracted to nuclei on two non-metal atoms.
Properties - Intermolecular forces are covalent, the forces between molecules are LDFs (weak), low melting/boiling points. Fullrenes are highly volatile.
Covalent Network Structures
Cosist of many thousands of atoms joined together by strong covalent bonding.
Four examples are: Carbon Diamond, Carbon Graphite, Boron and Silicon.
Do not conduct when molten
Carbon Diamond - Tetrahedral arrangement, making structures hard and strong as all four outer electrons form covalent bonds, doesn’t conduct. High thermal conductivity.
Carbon Graphite - Hexagonal rings, the fourth outer electron becomes delocalised, allowing it to conduct. Layers in graphite are held by weak LDF, so it can be used as a lubricant.
Properties - High melting points as strong covalent bonds need to be brkeon.
Monatomic elements
Examples are: the noble gases (monotomic elements).
They consist of single atoms which are not bonded to neighboring atoms. LDFs make their melting points very low. As you move down noble gases, melting points increased due to strong LDFs because of the increased number of electrons.
