1 / 19

Chemical Bonds

Chemical Bonds. Covalent Bond Non-polar vs. Polar Ionic Bond Hydrogen Bond Van der Waals Interactions. Strongest Weakest. Different Types of Bonds. In a covalent bond, two atoms share an electron. If two atoms share two electrons, the bond is called a double bond. C-H , O-H , H-H

wyatt
Download Presentation

Chemical Bonds

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chemical Bonds

  2. Covalent Bond Non-polar vs. Polar Ionic Bond Hydrogen Bond Van der Waals Interactions Strongest Weakest Different Types of Bonds

  3. In a covalent bond, two atoms share an electron. If two atoms share two electrons, the bond is called a double bond. C-H , O-H , H-H O=O , C=C Covalent Bonds

  4. Covalent Bonds • The only electrons that are shared between atoms are the valence electrons. • Valence electrons – the electrons found in the outermost shell of an atom

  5. Non-polar vs. Polar Covalent • The polarity of a covalent bond is based on the electronegativity of each atom. • If the electrons are shared equally, the bond is non-polar. • If the electrons are not shared equally, i.e. one atom pulls the electrons more than the other, a polar bond is formed.

  6. Ionic Bonds • In ionic bonds, one atom gives up a valence electron to another atom. • Called ionic compounds or salts • The atom losing the electron becomes positively charged. • The atom gaining the electron becomes negatively charged. • Ex. Table Salt NaCl = Na+-Cl

  7. Hydrogen Bond • Weak chemical bond • Very important to the chemistry of life • Occurs when one hydrogen atom covalently bonded to another electronegative atom is attracted to another electronegative atom. • Usually oxygen or nitrogen

  8. Van der Waals Interactions • Occur because electrons are not stationary. • Occur only when atoms are close together. • Atoms have positive and negative regions for brief moments.

  9. The Wonderful Properties of Water

  10. Properties of Water • Adhesion • Cohesion • Surface Tension • Polarity • High Specific Heat

  11. Adhesion • Adhesion = the clinging of one molecule to another • Ex. Adhesion of water to cell wall in plants helps fight gravity.

  12. Cohesion • The ability of water molecules to hold one to one another • Caused by H-bonds between the oxygen of one water molecules and the H of another water molecule

  13. Surface Tension • The measure of how difficult it is to stretch or break the surface of a liquid. • Because of waters cohesive property, water has a high surface tension. • Ex. Water striders are able to walk on ponds because of surface tension.

  14. Polarity • Results in Hydrogen bonding between water molecules • Hydrogen has a slightly positive charge. • Oxygen has a slightly negative charge. • This polarity makes water excellent at dissolving ions.

  15. Specific Heat • Specific Heat = the amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1°C • Specific Heat of water = 1 calorie/g/°C • Water has a high specific heat • Ethyl alcohol = 0.6 cal/g/°C

  16. Specific Heat • Since water has a high specific heat, it changes it’s temperature less. • This high specific heat is a result of the hydrogen bonds between the different water molecules. • Water has a high boiling point. • Is a strong evaporative coolant. • Less Dense as a solid. (Ice floats)

  17. Hydrophilic vs. Hydrophobic • Hydrophilic – water loving • Hydrophobic – water fearing • Hydrophilic molecules are polar and are ions. • Ex. Na+, NH3 • Hydrophobic molecules are non-polar and are not ions. • Ex. Fats and oils

  18. Macromolecules • Some larger molecules can have hydrophilic and hydrophobic portions. • These molecules will orient themselves in specific ways when placed into water.

  19. How are these properties make life on Earth possible?

More Related