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Chapter

Cover Making the Transition to University Chemistry

Bonding and Molecular Shape  

This chapter discusses bonding and molecular shape of electrons. A covalent bond occurs when atoms share a pair of similar electrons. Modern theories on covalent bonding are dominated by molecular orbital theory. Polar covalent bonds occur when different atoms share the electron pair unequally due to electronegativity. With benzene being the most familiar molecule of the bonding, delocalization happens when more than two atoms are involved in the bonding. The valence-shell electron-pair repulsion (VSEPR) theory can help us to visualize the shapes of simple molecules. Additionally, ionic bonding occurs when an atom transfers an electron to another atom and the ions formed a crystal lattice electrostatically.

Chapter

Cover Chemical Structure and Reactivity

Bonding between the elements  

This chapter describes what happens when different elements combine. The sizes of the orbitals involved and the number of valence electrons is important when considering the bonding in the elements, but when different elements combine there is the added complication that their orbital energies will be different. This leads to the possibilities of polar bonds and compounds in which electrons have essentially been transferred from one element to another, i.e. ionic compounds. Depending on the energy separation of the orbitals involved, the bonding can vary on a spectrum from purely covalent to ionic. Trying to predict the structure that a particular compound will adopt is very difficult. However, there are a few general concepts which can be applied to at least give some indication as to the likely structure. The concept of the radius ratio can help one to understand the different structures adopted by ionic solids.