Starter S-63 What is an ionic bond? What is a covalent bond?

Chapter 8 Covalent Bonding

Chapter 8 8.1 Molecular Compounds

8.1 Molecular Compounds Covalent Bond – held together by sharing electrons Molecule – a neutral group of atoms joined together by covalent bonds H2 Covalent Bond

8.1 Molecular Compounds Diatomic Molecules – the following atoms in their elemental state are molecules consisting of two atoms Hydrogen – H2 Nitrogen – N2 Oxygen – O2 Fluorine – F2 Chlorine – Cl2 Bromine – Br2 Iodine – I2

8.1 Molecular Compounds Molecule Example – Water Bonds within at atom are very strong Between molecules much weaker results in lower melting and boiling points Water

8.1 Molecular Compounds Molecular formula – shows the number of atoms of each element that are in a molecule

8.1 Molecular Compounds The formula does not show structure

Starter S-68 Which is the most interesting element that you have heard a presentation on? Why?

8.2 The Nature of Covalent Bonding Chapter 8 8.2 The Nature of Covalent Bonding

8.2 The Nature of Covalent Bonds In covalent bonds, electrons sharing usually occurs so that atoms attain the electron configuration of noble gases Hydrogen gets configuration of He Carbon gets configuration of Ne Chlorine – Ar Nitrogen – Ne Oxygen - Ne

8.2 The Nature of Covalent Bonds Single Covalent Bond Share one pair of electrons

8.2 The Nature of Covalent Bonds Bond dissociation energy – defined as the energy needed to break a bond The larger the bond dissociation energy, the stronger the covalent bond A C-C bond usually has about 347kJ/mol Bond Energy

8.2 The Nature of Covalent Bonds There are some exceptions to the octet rule

Starter S-69 What compound is formed from Carbon and Chlorine? What compound is formed from Oxygen and Carbon?

8.3 Polar Bonds and Molecules Chapter 8 8.3 Polar Bonds and Molecules

8.3 Polar Bonds and Molecules Bond Polarity Some atoms attract electrons more than others Atoms with greater Electronegativity attract more

8.3 Polar Bonds and Molecules If atoms have the same electronegativity then they perfectly share electrons This only occurs if the two atoms are the same element If they have different electronegativety values, then the electron stays around one atom more than the other

8.3 Polar Bonds and Molecules The result is a polar Bond H-H is non-polar H-Cl is polar

8.3 Polar Bonds and Molecules Molecules are polar if they are not symmetrical These molecules can be attracted to each other

8.3 Polar Bonds and Molecules Symmetrical molecules are nonpolar molecules There are polar bond But they cancel out s+ s-