Macromolecules-introduction
Learning outcomes
1. List chemical bonds found in cells
2. Describe main features of each bond
3. Summarise the monomer polymer cycle
Introduction
Molecules-groups of atoms, held together by stable association
Compounds- molecules containing more than one type of element
Atoms- held together by chemical bonds
Chemical bonds
Strong-covalent bonds
Medium-ionic bonds
Weak-hydrogen bonds, hydrophobic interactions, van der Waals attractions
Covalent bonds
Form when atoms share 2 or more valence electrons
Results in no net charge, satisfies octet rule, no unpaired electrons
Strength depends on number of paired electrons
Each H atom has an unpaired electron and n unfilled outer energy level, so it’s unstable
When 2 H atoms are close, each atoms electron is attracted to opposite atoms nucleus
The nuclei can share their electrons
E.g.
Single pair of electrons is weaker than 2 pairs, 2 pairs holds
tighter together as attraction to nuclei are higher.
Electron sharing diagram depicts how electrons are shared among covalently bonded
molecules
Double bond forms between 2 pairs of electrons
A polar covalent bond forms between 2 atoms that do not share electrons equally
In a polar covalent 1 atom has greater electronegativity producing
- A partial negative charge over part of the compound
Learning outcomes
1. List chemical bonds found in cells
2. Describe main features of each bond
3. Summarise the monomer polymer cycle
Introduction
Molecules-groups of atoms, held together by stable association
Compounds- molecules containing more than one type of element
Atoms- held together by chemical bonds
Chemical bonds
Strong-covalent bonds
Medium-ionic bonds
Weak-hydrogen bonds, hydrophobic interactions, van der Waals attractions
Covalent bonds
Form when atoms share 2 or more valence electrons
Results in no net charge, satisfies octet rule, no unpaired electrons
Strength depends on number of paired electrons
Each H atom has an unpaired electron and n unfilled outer energy level, so it’s unstable
When 2 H atoms are close, each atoms electron is attracted to opposite atoms nucleus
The nuclei can share their electrons
E.g.
Single pair of electrons is weaker than 2 pairs, 2 pairs holds
tighter together as attraction to nuclei are higher.
Electron sharing diagram depicts how electrons are shared among covalently bonded
molecules
Double bond forms between 2 pairs of electrons
A polar covalent bond forms between 2 atoms that do not share electrons equally
In a polar covalent 1 atom has greater electronegativity producing
- A partial negative charge over part of the compound
