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Chemistry of Life

Chemistry of Life. Chapter 6. Atoms. Matter- anything that has mass and takes up space Atom- smallest particle into which a substance can be divided and still retain its chemical properties. What makes up an atom?. Proton- subatomic particle in atom that has positive charge

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Chemistry of Life

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  1. Chemistry of Life Chapter 6

  2. Atoms • Matter- anything that has mass and takes up space • Atom- smallest particle into which a substance can be divided and still retain its chemical properties

  3. What makes up an atom? • Proton- subatomic particle in atom that has positive charge • Neutron- subatomic particle in atom that has no charge • Electron- subatomic particle in atom that has negative charge

  4. Understanding atoms • Nucleus- center of the atom where protons and neutrons are located • Electrons are found in the electron cloud

  5. Understanding atoms • Element- atoms with the same atomic number have the same chemical properties

  6. Isotopes • Isotopes- Atoms that have the same number of protons but different numbers of neutrons

  7. Uses of radioactive Isotopes • Medical • Tracer- a radioactive substance that is taken up and used by the body • Ex. An overactive thyroid gland may be a symptom of cancer and can easily be detected using radioactive tracers

  8. Compound • Elements can combine to form more complex structures • Compound- is a pure substance formed when two or more different elements combine

  9. Combining atoms • Covalent bond-chemical bonds that forms when electrons are shared • Molecule- is a compound held together by covalent bonds

  10. Covalent Bond

  11. Ionic bonds • Ionic Bond- chemical bond between two atoms that are attracted to each other by opposite charges • Think of how the positive and negative pole of a magnet attract

  12. Ionic Bonds

  13. Van der Waals forces • Van der Waals forces- attractive forces between positive and negative regions pull on molecules and hold them together

  14. Chemical Reactions • Chemical reactions- process by which atoms or groups of atoms in substances are reorganized into different groups • Reactants- starting substances • Left side of the arrow • Products- substance formed during reaction • Right side of the arrow

  15. Chemical reactions 2H2 + O2 2H20 Energy Reactants Products

  16. Chemical reactions • Activation energy- minimum amount of energy needed to start reaction • Enzyme- protein that can speed up the reaction

  17. Hydrogen bonds • Hydrogen bond- weak chemical bonds of a very special sort; play a key role in biology • A hydrogen bond occurs when the positive end of one polar molecule is attracted to the negative end of another • Think of two magnets

  18. Hydrogen bonds

  19. Water’s unique properties • H2O- oxygen atom linked to two hydrogen atoms by single covalent bond • Water is a polar molecule • Hydrogen bonds allow these properties

  20. Water’s unique properties • Heat storage • Many hydrogen bonds water molecules form together require large amount of thermal energy to disrupt organization • Water heats up slower than most compounds and holds temperature longer

  21. Water’s unique properties • Ice Formation • If temperature is low enough, very few hydrogen bonds will break Why is ice dense? • Hydrogen bonds keep water molecules spaced apart preventing them from approaching each other

  22. Water’s unique properties • High heat of vaporization • Temperature is high enough, many hydrogen bonds break in water, changing it from a liquid to a gas • How does sweating cool you off?

  23. Water’s unique properties • Cohesion- when a water molecule is attracted to another water molecule • Adhesion- when a water molecule is attracted to a different polar molecule • Capillary action is created by adhesion

  24. Water’s unique properties • High polarity • Water molecules in a solution always try to form maximum hydrogen bonds possible • Hydrophilic- polar molecules that attracted to water molecules • Soluble- dissolve in water • Hydrophobic-nonpolar compounds shrink from contact with water

  25. Water and solutions • Mixture- combination of two or more substances which each keeps its own properties • Homogenous mixture or solution- mixture that is uniform (same) composition

  26. Mixtures Homogenous Heterogeneous

  27. Homogenous mixture • Solvent- substance in which another substance is being dissolved • Water • Solute- substance that is dissolved in the solvent • powder

  28. pH • Acid- substances that release hydrogen ions (H+) when dissolved in water • Base- substance that release hydroxide ions (OH-) when dissolved in water • pH- concentration (amount) of H+ in a solution

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