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Chemistry of Life Chapters 4 & 5.

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Presentation on theme: "Chemistry of Life Chapters 4 & 5."— Presentation transcript:

1 Chemistry of Life Chapters 4 & 5


Matter made out of the same kind of atom is known as an ELEMENT There are 25 elements that are present in living organisms The four main ones are: Oxygen, Nitrogen, Carbon & Hydrogen Compounds are two or more elements chemically combined in a fixed ratio


5 What is an ATOM?

6 SUBATOMIC PARTICLE CHARGE MASS (in relation to other particles) LOCATION IN ATOM PROTON NEUTRON ELECTRON Generally, same number of protons as electrons When the number of Protons changes, the kind of atom changes Generally, the same number of protons as neutrons. If number of neutrons is greater than protons, then the atom is called an isotope

7 Periodic Table of Elements

8 Isotopes of Carbon



11 Electrons and bonding The number of electrons in the outer shell determines how an element will react with another Elements want to have “full” outer shells To have a full outer shell an element will either share or transfer electrons Ionic Bonding: elements transfer electrons Covalent Bonding: elements share electrons

12 Ionic Bond



15 Elementary sodium reacts strongly with water, according to the following reaction mechanism:
2Na(s) + 2H2O → 2NaOH(aq) + H2(g) A colourless solution is formed, consisting of strongly alkalic sodium hydroxide (caustic soda) and hydrogen gas. This is an exothermic reaction. Sodium metal is heated and may ignite and burn with a characteristic orange flame. Hydrogen gas released during the burning process reacts strongly with oxygen in the air. A number of sodium compounds do not react as strongly with water, but are strongly water soluble. Read more:

16 Ions When an atom loses or gains electron(s), the atom becomes an ion
If it loses electrons, it becomes positively charged If it gains electrons, it becomes negatively charged

17 Chemical Bonds Ionic bonds → TRANSFER of electrons
Covalent bonds → SHARING of electrons

18 Chemical Reactions In a chemical reaction the atoms of the reactants are rearranged to form the products of the reaction REACTANTS PRODUCTS ENERGY ENDOTHERMIC EXOTHERMIC



21 The structure of water Why is water such a unique substance?



24 Water structure

25 Water Properties COHESION ADHESION

26 Implications of Property in Nature
Properties of water Meaning Implications of Property in Nature Cohesion Adhesion Temperature Moderation Density of Ice Universal Solvent

27 In your group, read Water’s Life Supporting Properties section in your book (pp 82-84)
Each person is reading and filling on the table the info for one or two of the properties

28 Implications of Property in Nature
Meaning Implications of Property in Nature Cohesion Water molecules stick together due to H bonds Small animals may walk on water Adhesion Water molecules stick to other molecules Capillary action. Water pulled to top of trees Temperature Moderation Water makes it so changes in temperature do not happen quickly Animals can gradually change their internal system with changes in water temperature Density of Ice Ice is less dense than water so it floats Ice insulates organisms living beneath Universal Solvent Many compounds dissolve in water Dissolved compounds can be brought to cells (via sap or blood) or move about cell cytoplasm

29 pH scale


31 ACID compounds donate H+ ions to a solution (HCl)
BASE compounds donates OH- ions to a solution (NaOH) BUFFERS cause a solution to resist changes in pH


33 BIOMOLECULES What is the main chemical element present in all biomolecules?


35 ORGANIC COMPOUNDS: Carbon based

36 Molecules of life Carbohydrates Lipids Proteins Nucleic Acids

37 Notes Monomers – smallest unit of polymer
Polymer – Long chain of monomers linked together

38 Notes Carbohydrates: Organic compound made up of sugar molecules
Monosaccharides – one sugar unit Disaccharides – two sugar units Polysaccharides – long chains of sugar units

39 Notes on Lipids Lipids – Water-avoiding molecule (hydrophobic)
Two types of lipids: Fats – Three long fatty acid chains attached to glycerol molecule (saturated or unsaturated) Steroids – lipid molecule form of four fused rings (testosterone, estrogen & cholesterol)

40 NOTES ON NUCLEIC ACIDS Nucleic Acid: A large molecule made up of smaller molecules called nucleotides. Nucleotides: Small molecules made up of a sugar, a nitrogen base, and phosphate Nucleic acids are what our DNA or genetic material is made of With out nucleic acids our body would not have directions and could not function.


42 Notes on Proteins Proteins are made in cells by linking amino acids together to form polypeptide chains There are only 20 different amino acids Proteins are composed of one or more polypeptide chains The order of amino acids in polypeptide chains, and the three-dimensional shape of a protein molecule determines its function

43 Protein Shape The long Amino acid chain folds to make the protein useable A proteins shape is changed by its surroundings A protein that is outside of its normal environment will be denatured (misshapen)

44 Notes on Enzymes An enzyme is a type of protein
Each enzyme is specific to a kind of chemical reaction Enzymes are able to speed up chemical reactions in living cells by lowering the activation energy of the reaction Enzymes are affected by pH and temperature

45 Enzymes


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