The diagrams show two ways of representing this electron transfer. The slideshow shows dot and cross diagrams for the ions in sodium chloride, magnesium oxide and calcium chloride. Ionic bonding in sodium chloride. Ionic bonding in magnesium oxide. Below is a picture showing the electron sharing that occurs in the mineral diamond.
Diamonds are made of pure carbon and its the way that the carbon atoms are bonded that makes diamond the hardest substance. Each carbon atom has 4 electrons blue dots in its outer shell. This allows the atom to share electrons with 4 other carbon atoms surrounding it as the middle carbon atom is doing.
Each of these in turn will share the remaining 3 electrons with adjacent carbon atoms beside, above and below it, and those with other carbon atoms, etc. Similarly, covalent bonding between silicon and oxygen atoms makes strong bonds that form a large group of minerals called silicates more on those later.
Metallic bonds form when the outer shell electrons are shared between neighboring atoms. Unlike covalent bonding however, there are insufficient numbers of electrons in most metal atoms such as copper or silver to form pure covalent bonds. Therefore, the electrons are shared amongst all the nearest neighbor metal ions, forming a metallic bond. This strange arrangement of "metallic ions is a sea of electrons" gives metals their particular physical properties.
Metallic bonds are also explained by band theory. Band theory states that closely packed atoms have overlapping electron energy levels resulting in a conduction "band" wherein the electrons are free to roam between atoms, thus bonding them together. For more information on metallic bonds and band theory, see this web site. Van der Waals bonds are weak bonds that form due to the attraction of the positive nuclei and negative electron clouds of closely packed atoms.
This attraction is opposed by the repulsive force of the electron clouds and the repulsive force of neighboring nuclei. These positions, combined with ionic charge and size, determine the crystal structure of the solid crystal of which the ionic compound is composed.
So, although the chemical formula NaCl accurately represents the relative numbers of Na and Cl atoms in sodium chloride it does not imply that there are discrete molecules consisting of 1 Na and 1 Cl. For this reason it is not correct to refer to a molecule of sodium chloride because distinct molecules of ionic compounds do not exist as such. The stabilities of chemical compounds are all about energy. In general, the more energy released when a compound forms, the more stable the compound is.
Sodium chloride could be formed by reacting elemental solid sodium with elemental Cl 2 gas,. This reaction releases a large amount of energy and elemental sodium burns explosively in chlorine gas. The reaction can be viewed in terms of the following steps. The very large amount of energy involved in Step 5 is called the lattice energy and is primarily responsible for the high stability of ionic compounds.
A general picture of the energy involved is shown in Figure 4. The differences in ionic size noted above are represented in Figure 4. The figure shows that negative monatomic ions are generally larger than positive monatomic ions formed from elements that are nearby in the periodic table. It is. Figure 4. This occurs because as the charge of the nucleus becomes larger relative to the charge of the negative electron cloud around it, the cloud is drawn closer to the nucleus, shrinking ion size.
As electrons are added to atoms to produce more highly charged anions, the anion size increases because more electrons occupy more space. So S 2- ion is larger than Cl - ion. In order to further understand ion formation, several more examples can be considered.
Calcium and chlorine react,.
0コメント