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Chapter 2: The Chemistry of Life. ATOMS  Are the smallest particles of an element that has all the properties of that element  They are the building.

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Presentation on theme: "Chapter 2: The Chemistry of Life. ATOMS  Are the smallest particles of an element that has all the properties of that element  They are the building."— Presentation transcript:

1 Chapter 2: The Chemistry of Life

2 ATOMS  Are the smallest particles of an element that has all the properties of that element  They are the building blocks of matter  They are made up of smaller particles: protons, neutrons and electrons- arranged in a specific way.

3 Atoms continued…  MOST STABLE (unlikely to react) when outermost energy level is completely filled  Energy Levels- have a set maximum # of electrons Ion = atom that has lost or gained electrons Lose electrons= become positive ions Gain electrons= negative ions

4 Elements - a substance that cannot be broken down by chemical processes into simpler substances *Protons are positively charged *Neutrons have no electrical charge *Electrons are negatively charged and are located along the outside

5 Isotopes  Different number of neutrons, but same element  They have the same proton and electron number!

6 Compound two or more elements bonded together  Ex. H2O, NaCl  Compounds that contain CARBON and HYDROGEN together are termed, ORGANIC compounds

7 Chemical Bonds  Are the attractions that hold 2 or more atoms together to form a compound.  Whenever a chemical bond is formed or broken, energy is either absorbed or released

8 Ionic Bonds  the chemical bond formed from the attractive force between ions with opposite charges = NO ELECTRICAL CHARGE (electrons are lost by one element & gained by another)


10 2. Covalent Bonds  bonds in which electrons are NOT gained or lost, but shared.  Co - cooperative (sharing)  Ex. Water, carbohydrates, lipids, proteins and nucleic acids all have covalent bonds TYPES of Covalent BONDS SINGLE- 2 electrons shared DOUBLE- 4 electrons shared TRIPLE- 6 electrons shared

11 Types of bonds The units formed by covalent bonds are called molecules — most are made of atoms from different elements Some are not Ex. N2, O2

12 Polar Molecules  Atoms do not share electrons equally  There is a slightly negative end and a slightly positive end Ex. Water is POLAR

13 Van der Waals Forces  Intermolecular forces of attraction  Weaker forces than ionic or covalent bonds  Gecko example on page 39  Do section Assessment 2-1 #s 1-6

14 2-2 Properties of Water  Solutions : a uniform mixture of two or more substances  Water solutions are important because all of life’s chemical processes occur in solution  Uniform - mixed evenly so parts cannot be distinguished  2 Components (parts)  Solvent- dissolving substance found in greatest amount  Solute- Dissolved substance

15  Water = The Universal Solvent  Why? Because of polarity- dissolves polar molecules, ionic compounds

16 2 Properties of water  besides having hydrogen bonds (which are weak chemical attractions between hydrogen and other atoms)  1. Cohesion - “sticking together”: causes surface tension- a filmlike boundary forms on the surface of water  Adhesion: attraction of molecules of different substances  2. Expansion - water expands as it freezes  Ice has a lower density than liquid water  Ice floats on water D= m/vD>1= sink D<1= float

17 Acids, Bases and Salts  When ionic compounds are placed in water forming a solution, the compound breaks apart and releases ions.  Acid - A compound that releases Hydrogen Ions (H+) in water  Base - A compound that produces Hydroxide ions (OH-) when dissolved in water  Salt - Compounds that yield ions other than hydrogen or hydroxide ions when in solution, are called salts

18 pH SCALE  pH scale is the standard measurement of the concentration of hydrogen ions (H+) present in a solution  p= “power H= hydrogen ion concentration  pH scale ranges from 0 to 14 0 7 14 ACIDSBASES NEUTRAL

19 2- 3 Carbon Compounds  Carbon has 4 valence electrons. Can bind with many elements and to each other. Organic Chemistry is the study of carbon and hydrogen compounds.  Most abundant elements in our body : Don’t CHNO: carbon, Hydrogen, nitrogen and oxygen  Macromolecules: large molecules are formed by a process called polymeriazation  Monomers + monomers + monomers= polymers

20  Four groups of organic compounds found in living things:  1. Carbohydrates: sugars starches and cellulose—living things use carbs as main energy source and structural purposes Sugars: mono, di and polysaccacharide  Animals use glycogen  Plants use starch

21  2. lipids: fats, oils and waxes—Can be used to store energy, they are important parts of membranes and waterproof coverings.

22  3. nucleic acids : store and transmit hereditary or genetic information--- made of monomers called nucleotides  3 PARTS!! 2 Kinds DNA Deoxyribonucleic acid RNA: ribonucleic acid

23  4. Proteins: made up of smaller units called amino acids (Amino because has an NH2 on one end and a –COOH on the other) Very important: Protein Synthesis in cells Functions: Defense(antibodies), movement(actin/myosin), Transport (hemoglobin), hair and nails (keratin)


25 2-4 Chemical Reactions and Enzymes  Chemical Reactions : a process that changes one set of chemicals into another set of chemicals  They always involve the breaking of bond in the reactants and the formation of new bonds in the products  Example ( Label the reactants and products)  CO 2 + H 2 O H 2 CO 3

26 Energy in Reactions  Energy is released or absorbed whenever chemical bonds form or are broken  Chemical reactions that release energy often occur spontaneously. Chemical reactions that absorb energy will not occur without a source of energy.

27  Energy Releasing 2H 2 + O 2 2H 2 O Energy Absorbing 2H 2 O2H 2 + O 2

28 Energy Releasing (Exothermic) Activation Energy- the energy needed to get a reaction started

29 Energy Absorbing (Endothermic)

30  Catalyst: is a substance that speeds up the rate of a chemical reaction- they work by LOWERING the activation energy  ENZYMES are protein catalysts

31 Enzyme - Substrate Complex  Substrate = reactant, substance to be changed  Active site = where the substrate attaches

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