CHEM 1000 Chapter Notes - Chapter 9: Noble Gas, Metal, Periodic Trends
Document Summary
Chem 1000: the periodic table and atomic properties. Includes the noble (inert) gases as a special case. In between metal and non-metals, have some properties of metals and non-metals: semiconductors, noble gases, have full valence shell, this gives extreme stability and chemical inertness. It appears most elements try to achieve this stability by acquiring or losing electrons. Size of atoms and ions: covalent radius, half of the distance between identical atoms in a covalent compound. Effective charge: for sodium and magnesium, the last electron goes into the 3s orbital, we define effective nuclear charge as the nuclear charge, z, minus the charge that is shielded out by the inner electrons, (cid:3032)(cid:3033)(cid:3033)= (cid:1845, = (cid:1844)2(cid:3280)(cid:3281)(cid:3281)2. In sodium zeff = 1 and in magnesium zeff = 2: hence the magnesium atom is smaller, this carries across the period with the atoms getting smaller.
