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Biochemistry for nurses
The Chemical Bonds
مهني. حكيم دDr Hakim Mehenni
Email: [email protected]
https://sites.google.com/site/drhakimmehenni/
Biochemistry for nurses
The Chemical Bonds • The chemical bond is a link between 2 atoms to give a molecule. • The chemical bond is composed by 2 electrons coming from the outer
layer of each different atom to make a pair of electron. • 4 types of chemical bonds: Nonpolar covalent bond, Polar covalent
bond, Ionic bond and Hydrogen bond.
nucleus
Outler electron
ATOM (hydrogen, oxygen, carbon…)
Biochemistry for nurses
Nonpolar covalent bond • Same forces of attraction onto the electron pair • The electron pair is situated at same distance
between the 2 atoms.• Often between same atoms (H2, O2, C4…)
Attractive forces (A = B)
Biochemistry for nurses
Polar covalent bond • Different forces of attraction onto the electron pair • The electron pair is situated closer to the more electronegative
atom than other.• Often between 2 different atoms (H2O, NH3, CH4…)
• Attractive force of B > attractive force of A
• Electronegativity of B > electronegativity of A
• Donor atom (δ+) = A
• Acceptor atom (δ-) = B
Biochemistry for nurses
Polar Molecules
Biochemistry for nurses
Ionic bond • An atom can win or lose electrons: Oxidation = the atom loses electrons
(ex: Na+); Reduction = the atom wins electrons (ex: Cl-). • The Oxidation and Reduction produce Ions. An ion is atom having a
missing electron (+) or an extra electron (-). An ion is electrically charged + or –
• An ionic bond is an interaction (attraction) between 2 ions having opposite signs.
Ionic compounds are salts!
Biochemistry for nurses
Hydrogen bond • A hydrogen bond is a attraction between polar molecules that occurs when a hydrogen (H) atom is bound to a highly electronegative atom (acceptor atom(δ-)). That hydrogen (donor δ+) is attracted towards some other nearby highly electronegative atom such as Oxygen (O), Nitrogen (N), Fluorine (F).
Biochemistry for nurses
• These Hydrogen bonds can occur between different molecules (intermolecular) such as water, or within different parts of the same molecule (intramolecular) such as DNA.
• The hydrogen bond is weaker than covalent and ionic
WATER
DNA
Biochemistry for nurses
