1.1 Atoms and Bonding

Atoms and Elements

Ionic Bonding sodium atom (Na) sodium ion (Na + ) 11 protons (+) 10 electrons (-) one (+) charge 11p 12n 11p 12n + electron given up

Ionic Bonding 17p 18n 17p 18n electron accepted 17 protons (+) 18 electrons (-) one (-) charge chlorine atom (Cl) chlorine ion (Cl - ) -

Ionic Bonding 11p 12n 17p 18n Na Cl +

Ionic Bonding sodium chloride (NaCl) 11p 12n + 17p 18n -

Covalent Bonding Cl + Cl 17p 18n 17p 18n

Covalent Bonding Cl-Cl chlorine gas (Cl 2 ) 17p 18n 17p 18n

Electronegativity larger eletronegativity - smaller electronegativity = difference in electronegativity

Electronegativity Examples: O 2 -> oxygen has an EN of 3.44 3.44 - 3.44 = 0 ∆ EN = 0, therefore each atom in an oxygen molecule has an equal attraction for the bonding pair of electrons. This is a covalent bond.

Electronegativity Examples: HCl -> H has an EN of 2.20, Cl has an EN of 3.16 3.16 - 2.20 = 0.96 ∆ EN = 0.96, therefore chlorine has a slightly great pull on the bonding pair of electrons. This is a polar covalent bond.

Electronegativity Examples: NaCl -> Na has an EN of 0.93, Cl has an EN of 3.16 3.16 - 0.93 = 2.23 ∆ EN = 2.23, therefore chlorine has a substantially greater pull on the bonding pair of electrons. This is an ionic bond.

Hydrogen Bonding hydrogen bonding in water