The chemical properties of the elements reflect their electron configurations. The highest occupied electron shell is called the valence shell, and the electrons occupying this shell are called valence electrons.
In the third period of the table, the atoms all have a neon-like core of 10 electrons, and shell #3 is occupied progressively with eight electrons, starting with the 3s-orbital. As we progress from lithium (atomic number=3) to neon (atomic number=10) across the second row or period of the table, all these atoms start with a filled 1s-orbital, and the 2s-orbital is occupied with an electron pair before the 2p-orbitals are filled. Shell #2 has four higher energy orbitals, the 2s-orbital being lower in energy than the three 2p-orbitals. According to the Aufbau principle, the electrons of an atom occupy quantum levels or orbitals starting from the lowest energy level, and proceeding to the highest, with each orbital holding a maximum of two paired electrons (opposite spins).Įlectron shell #1 has the lowest energy and its s-orbital is the first to be filled. The truncated periodic table shown above provides the orbital electronic structure for the first eighteen elements (hydrogen through argon). Consequently, our understanding of organic chemistry must have, as a foundation, an appreciation of the electronic structure and properties of these elements. The periodic table shown here is severely truncated there are over eighty other elements.įor links to complete periodic tables Click Here.įour elements, hydrogen, carbon, oxygen and nitrogen, are the major components of most organic compounds. Electron Configurations in the Periodic Table 1A This chapter introduces some basic facts and principles that are needed for a discussion of organic molecules. The study of organic chemistry must therefore extend to the molecular level, for the physical and chemical properties of a substance are ultimately explained in terms of the structure and bonding of molecules. Molecules of organic compounds are made up of discrete collections of atoms that are held together (bonded) in three-dimensional space in a unique constitution and configuration, referred to as its structure.
Introduction to Organic Chemistry Structure & Bonding
0 kommentar(er)
