Bonding Essay

1874 Words Dec 15th, 2013 8 Pages
Bonding
Topic 4 IB Chemistry

What is a bond?


A force that holds atoms together and makes them function as a unit Atoms bond to achieve a noble gas electron configuration (8 electrons in the outer level - octet rule)




H and He are notable exceptions - only need 2 electrons (duet rule) The valence electrons (electrons in the outermost energy level) are the ones involved



Ionic Bonds


The electrostatic attraction between oppositely charged ions (cation = +; anion = -) Results from the transfer of e- from a low electronegative atom (cation, metal) to a high electronegative atom (anion, non-metal) so both achieve complete outer shells (inert gas econfiguration)





Ionic bonds occur if the difference in
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High melting and boiling points (NaCl melts at 800˚C) 2. Solid at room temperature 3. Soluble (dissolve) in water 4. Do not conduct electricity when solid (electrons held tightly and do not move) 5. Conduct electricity when dissolved in water (ions exist that can move a carry a charge)

Dissolving NaCl animation

Covalent Bonds


The electrostatic attraction between a pair of electrons and positively charged nuclei; electrons are shared in order to achieve a noble gas electron arrangement


Electrons will be shared if the difference between the electronegativities of the atoms involved is less than 1.8



Duet Rule - hydrogen only requires a total of 2 electrons (1 more needed) to take on an electron configuration of Ne Octet Rule - other atoms will share electrons in order to achieve an electron configuration with 8 electrons in the outer shell To help determine how atoms will share electrons, we use Lewis structures





Lewis Structures


Lewis structures (a.k.a. electron dot diagrams) help show the valence electrons of atoms


Simply the symbol of the element surrounded by the number of valence electrons Helps show how atoms will come together to achieve the stable electron configuration



Na• • C • •

xx



O x [ Cl ]x ••
•• ••

xx

••

K+



Draw the Lewis

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