Chapter 6 Chemical bonding

Ionization energy unit of measurement (Kj/mol) Ionization energy ( IE ) Is the energy required to remove an electron from a neutral atom Ionization energy ( IE ) is increased the more electrons that are removed from an atom

electronegativity Is an atom’s ability in a chemical compound to attract electrons from another atom in the compound In other words, electronegativity is an atoms ability to attract electrons

Flourine has the highest electronegativity of 4

Chemical bonding A chemical bond is a mutual attraction between the nuclei and valence electrons of different atoms that binds the atoms together

Three types of chemical bonds Ionic bond Covalent bond a) nonpolar covalent b) polar covalent Metallic bond

Unbonded atoms have high potential energy and are considered to be unstable. Nature favors arrangement of atoms with minimum potential energy. So…by atoms bonding together into compounds the atoms lower their potential energy and create a more stable arrangement

Ionic bond Ionic bond – forms from the electrical attraction between cations and anions NaCl is an example of an ionic bond Na forms a 1+ ion Na+1 (cation) Cl forms a 1- ion Cl-1 (anion) The positive sodium ion and negative chlorine ion attract each other

Covalent Bond Covalent bond – forms from two or more atoms sharing valence electrons Example: H2O H has 1 valence electron ( 2 H atoms) O has 6 valence electrons With H and O sharing their electrons, O’s highest energy level is complete w/ 8 valence electrons and H’s highest energy level is complete with 2 valence electrons

2 types of covalent bonds polar covalent and nonpolar covalent Nonpolar covalent bond is a bond where the valence electrons are shared equally by the atoms, resulting in a balanced electrical charge. = =

2 types of covalent bonds polar covalent and nonpolar covalent Polar covalent bond is a covalent bond in which the bonded atoms have an unequal attraction for the shared electrons. This affects the atoms where one atom is slightly positive and the other atom is slightly negative. + _ Slightly slightly Positive negative

So how do we tell if the bond is ionic or covalent?

Difference in electronegativity Each element has it’s own electronegativity. If we find the difference in electronegativity we can determine the bond type, ionic or Covalent ( nonpolar or polar)

A hydrogen hydrogen bond is nonpolar covalent. Hydrogen electronegativity is 2.1, 2.1 – 2.1 = 0 difference in electronegativity. Sodium and chlorine bond in an ionic bond Na 0.9 and Cl 3.0, 3.0 – 0.9 = 2.1 difference in electronegativity Cu 1.9 bonds with Cl 3.0, 3.0 – 1.9 = 1.1 difference in electronegativity creates a polar bond, where the Electrons are drawn closer to chlorine (higher Electronegativity)

Percentage ionic character - states,as a percentage, how close the bond is to being 100% ionic