ch9notes - Chapter 9 Chemical Bonds 2010 Donald L. Siegel,...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
©2010 Donald L. Siegel, All Rights Reserved Chapter 9 Chapter 9 Chemical Bonds
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
©2010 Donald L. Siegel, All Rights Reserved What are bonds? What are bonds? W Because the nuclei cannot change, the formation of bonds has to involve the electrons W Because the inner core electrons are held so tightly, it must be the valence electrons
Background image of page 2
©2010 Donald L. Siegel, All Rights Reserved Representing valence Representing valence electrons electrons W Lewis symbols are a convenient representation of atoms and their valence electrons W Symbol surrounded by one dot for each valence electron Location doesn’t matter Put paired electrons together
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
©2010 Donald L. Siegel, All Rights Reserved Examples Examples H He : Li Be : B : C : N : :O : :F :
Background image of page 4
©2010 Donald L. Siegel, All Rights Reserved Ionic Bonds Ionic Bonds W Ionic compounds are formed from the transfer of electrons W The coulombic attraction of cation and anion for each other are what hold in together This force is the so-called “ionic bond” Lewis formula shows the transferred electrons W Most stable configuration octet for elements past the first period duplet for the first period Noble gas-like configuration
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
©2010 Donald L. Siegel, All Rights Reserved Molecular compounds Molecular compounds W Do not form ionic bonds W Electrons simultaneously occupy orbitals from each atom share electrons must be paired (just like atomic orbitals)
Background image of page 6
©2010 Donald L. Siegel, All Rights Reserved What happens when a bond forms What happens when a bond forms
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
©2010 Donald L. Siegel, All Rights Reserved Extra energy? Extra energy? W It takes 436 kJ to pull apart H 2 and 159 kJ to separate F 2 W Thus it should take (436+159)/2 = 298 kJ separate H-F W It actually takes 565 kJ W Where does the extra energy come from? In addition to the energy from the chemical bond, there is some electrostatic interaction The F is partly negative and the H is partly postive W Linus Pauling developed a scale based on the sum of the electron affinity and the ionization energy
Background image of page 8
©2010 Donald L. Siegel, All Rights Reserved What What electronegativity electronegativity means means W The more electronegative an atom is, the strong the pull on the electron pair W The thing that matters is the difference in electronegativity If one atom is enough more electronegative, the electrons spend all the time around that atom (ionic) If the difference is zero, the electrons are shared equally (covalent)
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
©2010 Donald L. Siegel, All Rights Reserved
Background image of page 10
©2010 Donald L. Siegel, All Rights Reserved Ionic vs. covalent Ionic vs. covalent W By combining electron affinity and ionization energy, we get a predictor or how much attraction an atom has for a shared pair of electrons. more regular than either ionization or electron affinity atoms are more electronegative toward the upper right, more electropositive towards the lower left
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
©2010 Donald L. Siegel, All Rights Reserved
Background image of page 12
©2010 Donald L. Siegel, All Rights Reserved
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
©2010 Donald L. Siegel, All Rights Reserved Lattice Enthalpies Lattice Enthalpies W
Background image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 66

ch9notes - Chapter 9 Chemical Bonds 2010 Donald L. Siegel,...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online