|Matters and Properties of Matters|
|Atomic Structure with Examples|
|The Mole Concept with Examples|
|Gases with Examples|
|Chemical Reactions with Examples|
|Nuclear Chemistry (Radioactivity)|
|Acids and Bases|
|Rates of Reactions (Chemical Kinetics)|
|--Polarity of Bonds|
|--Metallic and Molecular Bonds|
|--Chemical Bonds Cheat Sheet|
|Exams and Problem Solutions|
Bond that keeps metal atoms together is called metallic bond. In metals;
Valence electrons of metals can jump to the other atom's valence orbitals. This free movement of electrons makes metals good conductor of electricity and heat. All valence electrons of metals can behave like this.
Atoms bonded with covalent bonds produce molecules and these molecules attract each other and form secondary bonds. Molecular bonds determine physical properties like melting point, boiling point of matters. Moreover, they also determine physical states of matters.We examine these bonds under three titles, Vander Waals Bond, Dipole-Dipole Interactions and Hydrogen Bond.
1) Van der Waals Bonds:
We see these bonds in molecules having % 100 nonpolar bonds like, I2, Cl2, H2 and molecules having polar bonds but nonpolar molecules like CO2. When nonpolar molecules like CO2 are get closer,they repel each other and symmetry of molecule is broken. And then, positive and negative dipoles are formed in molecule. An instant attraction of these dipoles each other is called Van der Waals bonds. Increasing molar mass increases strength of van der waals bonds.
2) Dipole-Dipole Interaction:
This types of bond is seen between polar molecules in solid and liquid phases such as, HCl, SO2, H2S, PH3. Since there is no symmetry in polar molecules, there are poles having negative and positive charges. Attraction between these poles in molecule is called dipole-dipole interaction. These forces are not temporary as in the case of va der waals bonds. Thus, dipole-dipole interactions are stronger than van der waals bonds. Molecules having closer molar masses have different boiling points. Polar molecules have higher boiling point than nonpolar molecules because of strengths of dipole-dipole interactions.
3) Hydrogen Bonds:
Chemical bonds formed between H and atoms having high electronegativity like F, N O, are stronger than dipole-dipole interactions. We can explain this ;
Since O has high electronegativity, it attracts H in H-O bond strongly and these bonds are called hydrogen bond. In other words, attraction between H atom of one molecule and O atom of another molecule is called hydrogen bond. We can show schema of hydrogen bond in water as given below;
Compounds including hydrogen bonds have higher boiling and melting points than compounds having van der waals bonds and dipole-dipole interactions.
Bonds in solid State:
We can analyze bonds in solids under four categories.
1) Ionic Solids:
Solids that are bonded with ionic bonds are called ionic solids. They ;
2) Covalent Solids:
They are huge molecules formed by covalent bonds. diamond, graphite, SiC are examples of covalent solids.They;
3) Molecular Solids:
They are solids including van der waals bonds, dipole-dipole interactions or hydrogen bonds. They;
4) Metallic Solids:
Metals including metallic bond are produce this group. This solidification can be seen in all pure metals and alloys. Fe, Au, Ag, Cr are some common examples of metallic solids. They;