The structure of_matter


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The structure of_matter

  1. 1. The Structure of Matter Chapter 2: Chemical Basis of Life
  2. 2. What is Matter? <ul><li>Matter is anything that has weight and takes up space. </li></ul><ul><ul><li>This includes the solids, liquids, and gases in our surroundings, as well as inside our bodies. </li></ul></ul>
  3. 3. What is it Made of? <ul><li>All matter is composed of substances called Elements . </li></ul><ul><ul><li>At present, 111 elements are known, although naturally occurring matter on Earth includes only 92 of them. </li></ul></ul><ul><ul><ul><li>Although some of these elements exist in a pure form, they occur more frequently in mixtures of chemical combinations. </li></ul></ul></ul>
  4. 4. Elements We Need <ul><li>Living organisms require about 20 elements. </li></ul><ul><ul><li>Of these carbon, hydrogen, oxygen, phosphate, nitrogen, sulfur make up more than 98% (by weight) of the human body. </li></ul></ul>
  5. 5. Elements <ul><li>Elements are composed of tiny particles called Atoms , which are the smallest complete units of elements. </li></ul><ul><ul><li>All the atoms of an element look nearly identical to one another, but different from atoms of another element. </li></ul></ul><ul><ul><ul><li>Atoms vary in size, weight, and the ways they interact with each other. </li></ul></ul></ul>
  6. 6. How are they different? Oxygen Carbon
  7. 7. Atomic Structure <ul><li>An atom consists of a central portion, called the Nucleus , and one or more Electrons that move around it. </li></ul><ul><ul><li>The nucleus contains one or more relatively large particles called Protons . </li></ul></ul><ul><ul><ul><li>The nucleus also usually contains one or more Neutrons , which are similar in size to protons. </li></ul></ul></ul>
  8. 8. More on Atomic Structure <ul><li>Electrons (extremely tiny) each carry a single, negative electrical charge </li></ul><ul><li>Protons each carry a single, positive electrical charge. </li></ul><ul><li>Neutrons are uncharged and are electrically neutral. </li></ul>
  9. 10. Chemistry Vocab. Review <ul><li>Atomic Number : the number of protons in the atoms of a particular element. </li></ul>
  10. 11. Chemistry Vocab. Review <ul><li>Atomic Weight : Approximately the number of protons plus the number of neutrons in each of an element’s atoms. </li></ul>
  11. 12. Let’s Bond! <ul><li>When atoms combine with other atoms, they either gain electrons, lose electrons, or share electrons. </li></ul><ul><ul><li>The electrons of an atom occupy one or more areas of space called Shells around the nucleus. </li></ul></ul><ul><ul><ul><li>The outermost shell of an atom determines its chemical behavior. </li></ul></ul></ul>
  12. 13. Stability vs. Instability <ul><li>Atoms whose outermost electron shells are filled, have stable structures and are chemically inactive ( inert )- Example : Helium </li></ul><ul><li>Atoms whose outermost electron shells are incompletely filled, tend to gain, lose, or share electrons in ways that empty or fill their outer shells. </li></ul><ul><ul><ul><li>In this way, they achieve stable structures. </li></ul></ul></ul>
  13. 14. Types of Bonds <ul><li>1. Ionic Bonds </li></ul><ul><li>2. Covalent Bonds </li></ul><ul><li>3. Hydrogen Bonds </li></ul>
  14. 15. Ionic Bonding <ul><li>An Ionic Bond is a chemical bond formed between two (oppositely charged) ions by the transferring of electrons . </li></ul><ul><ul><li>Example : Sodium ions (Na + ) and chloride ions (Cl - ) uniting in this manner form the compound sodium chloride (NaCl), or table salt. </li></ul></ul>
  15. 17. Covalent Bonding <ul><li>Nature likes filled levels for stability, why not share? </li></ul><ul><ul><li>A Covalent Bond is a chemical bond formed by electron sharing between atoms. </li></ul></ul>
  16. 19. Hydrogen Bonding <ul><li>A Hydrogen Bond is a weak electrical attraction between a hydrogen atom (covalently bound to a nitrogen or oxygen atom) and another nitrogen or oxygen atom nearby . </li></ul>
  17. 20. Hydrogen Bonding <ul><li>Hydrogen bonds only occur with molecules that are polar . </li></ul><ul><li>Water is polar because the oxygen atom & hydrogen atoms share electrons unevenly. </li></ul>
  18. 21. Molecules & Compounds <ul><li>When two or more atoms bond, they form a new kind of particle called a Molecule . </li></ul><ul><ul><li>If atoms of the same element combine, they produce molecules of that element. </li></ul></ul><ul><ul><li>Example: H 2 , O 2 </li></ul></ul><ul><li>When atoms of different elements combine, they form molecules called Compounds . </li></ul><ul><ul><li>A molecule of a compound always contains definite kinds and numbers of atoms. </li></ul></ul><ul><ul><li>Example: CO 6 , H 2 O, C 6 H 12 O 6 </li></ul></ul>
  19. 22. Chemical Reactions <ul><li>Chemical rxns form or break bonds between atoms, ions, or molecules, generating new chemical combinations. </li></ul><ul><ul><li>1. Synthesis Reactions </li></ul></ul><ul><ul><li>2. Decomposition Reactions </li></ul></ul><ul><ul><li>3. Exchange Reactions </li></ul></ul><ul><ul><li>4. Reversible Reactions </li></ul></ul>
  20. 23. Synthesis Reactions <ul><li>When two or more atoms (reactants) bond to form a more complex structure (product). </li></ul><ul><li>A + B  AB </li></ul><ul><li>Requires an input of energy (endergonic) </li></ul><ul><li>Important in the growth of body parts and the repair of worn or damaged tissues. </li></ul>
  21. 24. Decomposition Reactions <ul><li>When the bonds within a reactant molecule break so that simpler molecules, atoms, or ions form. </li></ul><ul><li>AB  A + B </li></ul><ul><li>Decomposition occurs when foods are digested and energy is released (exergonic) </li></ul>
  22. 25. Exchange Reaction <ul><li>Parts of two different types of molecules trade positions. </li></ul><ul><li>AB + CD  AD + CB </li></ul><ul><li>An example is when an acid reacts with a base, producing water and a salt. </li></ul><ul><ul><li>HCl + NaOH --> NaCl + H 2 O </li></ul></ul>
  23. 26. Reversible Reactions <ul><li>Most chemical reactions are reversible. </li></ul><ul><ul><li>The product (or products) of the reaction can change back to the reactant (or reactants) that originally underwent the reaction. </li></ul></ul><ul><ul><li>A + B   AB </li></ul></ul>
  24. 27. Understanding Electrolytes <ul><li>Some compounds release ions when they dissolve in water or react with water molecules. </li></ul><ul><ul><li>Example : NaCl releases sodium ions (Na + ) and chloride ions (Cl - ) when it dissolves: </li></ul></ul><ul><ul><li>NaCl  Na + + Cl - </li></ul></ul>
  25. 28. Understanding Electrolytes <ul><li>NaCl  Na + + Cl - </li></ul><ul><li>Since the resulting solution contains electrically charged particles (ions), it will conduct an electric current. </li></ul><ul><ul><li>Substances that release ions in water are called Electrolytes . </li></ul></ul>
  26. 29. Acids & Bases <ul><li>Electrolytes that release hydrogen ions in water (H + ) are called Acids . </li></ul><ul><ul><li>Example : In water, the compound hydrochloric acid (HCl) releases hydrogen ions (H + ) and chloride ions (Cl - ) </li></ul></ul><ul><li>Electrolytes that release hydroxide ions in water (OH - ) are called Bases . </li></ul><ul><ul><li>Example : The compound sodium hydroxide (NaOH) releases hydroxide ions (OH - ) when placed in water. </li></ul></ul>
  27. 30. pH Scale <ul><li>A value called pH measures hydrogen ion concentration. </li></ul><ul><ul><li>The pH scale ranges from 0 to 14. </li></ul></ul><ul><ul><ul><li>A solution that contains equal numbers of hydrogen and hydroxide ions is said to be neutral, and has a pH of 7. </li></ul></ul></ul><ul><ul><ul><li>A solution that contains more hydrogen than hydroxide ions has a pH less than 7 </li></ul></ul></ul><ul><ul><ul><li>A solution that contains less hydrogen than hydroxide ions has a pH more than 7 </li></ul></ul></ul><ul><ul><ul><li>Each whole number on the scale represents a tenfold difference in hydrogen ion concentration. </li></ul></ul></ul>
  28. 31. Human Implications <ul><li>The pH of human blood is about 7.4 (range is from 7.35 to 7.45) </li></ul><ul><ul><li>If this pH value drops below 7.35, the person is said to have Acidosis </li></ul></ul><ul><ul><li>If this pH value rises above 7.45, the person is said to have Alkalosis </li></ul></ul><ul><ul><ul><li>Without medical intervention, a person usually cannot survive if blood pH drops to 6.9 or rises to 7.8 for more than a few hours. </li></ul></ul></ul>