· Covalent: when atoms share electrons from their outer shell, to fill both outer shells
· Ionic: ions with opposite charges attract. The electrostatic attraction is an ionic bond
· Hydrogen: electrons within a molecule are not evenly distributed. A molecule with uneven distribution of charge is called a polar molecule. The negative region of one molecule attracts to the positively charged region of another forming a weak electrostatic bond.
· Monomers can be linked to form long chains called polymers. They are formed through polymerisation
· Monosaccharides join to form polysaccharides
· Peptides joint to form polypeptides
Condensation and hydrolysis:
· Polymerisation is a condensation reaction because a water molecule is formed
· Polymers can be broken down using water in a reaction called hydrolysis.
· All the chemical processes that take place in living organisms
Mole and molar solutions:
· The mole is the SI unit for measuring the amount of a substance (mol)
· One mole has the same number of particles as in 12g of carbon-12 atoms.
· A molar solution is a solution that contains one mole of solute in each litre of solution
· Smallest unit of a chemical element.
· Has a nucleus with protons and neutrons
· Electrons orbit the nucleus
· Protons – occur in the nucleus and have the same mass as neutrons with a positive charge
· Neutrons – occur in the nucleus and have the same mass as protons with no charge
· Electrons – orbit in shells around the nucleus. Tiny mass. They are negatively charged and the quantity determines the properties of an atom
· Atomic number – the number of protons in an atom
· Mass number – the number of protons and neutrons in an atom
· Different types of atoms are called isotopes
· If an atom loses or gains an electron it becomes an ion
· Carbon molecules combine with water
· Readily form bonds with other carbon atoms
· Large number of different types and sizes of molecules can be formed
· The variety of life that exists on earth is a consequence of living organisms being based on the carbon atom
· Monomers join to form polymers
· Monosaccharides can be joined to form disaccharides (two) and polysaccharides
· Sweet tasting soluble substances
· Glucose, galactose and fructose
· Glucose is a hexose (6 carbon sugar)
· Alpha and beta glucose
Testing for reducing sugars
· All monosaccharides and some disaccharides are reducing sugars
· Reduction is a chemical reaction involving the gain of electrons or hydrogen.
· Benedict’s test:
· Alkaline solution – copper sulphate
· Forms an insoluble…