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The Chemistry of Life: Atoms, Bonds, and Water

This chapter discusses the subatomic particles that make up atoms, the similarities of isotopes, the types of chemical bonds, and the properties of water. It explores how these concepts are crucial for understanding the chemistry of life.

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The Chemistry of Life: Atoms, Bonds, and Water

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  1. Chapter 2 The Chemistry of Life

  2. Section 1: The Nature of Matter

  3. Objectives • What three subatomic particles make up atoms? • How are all the isotopes of an element similar? • What are the two types of chemical bonds?

  4. The Big Idea • Life Depends on chemistry • Chemical reactions keep you alive

  5. Atom • Basic unit of matter

  6. Democrites

  7. Protons - Neutrons - Electrons - Positively charged (+) Not charged (neutral) Negatively charged (-) Subatomic particles Bind together to form the nucleus Protons Electrons Nucleus Neutrons

  8. Element • A pure substance that consists of just one type of atom

  9. An elements atomic number = number of protons Atomic number 6 C Carbon 12.011

  10. Isotope • Atoms of the same element that differ in the number of neutrons they contain

  11. Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons 6 electrons 6 protons 8 neutrons

  12. Radioactive isotopes • Can be dangerous • Can be used practically • Radioactive dating • Treat cancer • Kill bacteria

  13. What is the atomic mass? • The weighted average of the masses of an elements isotope is called its atomic mass

  14. Compounds • A substance formed by the chemical combination of two or more elements in definite proportions • Ex) H2O, NaCl

  15. Ionic Bonds • Formed when one or more electrons are transferred from one atom to another

  16. The Sum of protons and neutrons in the nucleus of an atom is its mass number 6 C Carbon Mass number 12.011

  17. What is an Ions? • Positively and negatively charged atoms

  18. If an atom loses an electron it becomes positive + (Cations) • If an atom gains an electron it becomes negative - (Anions)

  19. Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1

  20. Covalent Bonds • Forms when electrons are shared between atoms

  21. Molecule • The structure that results when atoms are joined together by a covalent bond • Smallest unit of most compounds

  22. Van der Waals Forces • A slight attraction that develops between the oppositely charged regions of nearby molecules due to unequal sharing of electrons

  23. Questions

  24. Describe the structure of an atom. Atoms are made up of protons and neutrons in a nucleus. Electrons are in constant motion in the space around the nucleus. • Why do all isotopes of an element have the same chemical properties They have the same number of electrons

  25. 3. What is a covalent bond? A bond formed when electrons are shared between atoms 4. What is a compound? How are they related to molecules A compound is a substance formed by the chemical combination of two or more elements in definite proportions. A molecule is the smallest unit of most compounds

  26. 5. How do Van der Waals forces hold molecules together? When the sharing of electrons are unequal, a molecule has regions that are charged. An attraction can occur between oppositely charged regions of nearby molecules

  27. 6. How are ionic bonds and Van der Waals forces similar? How are they different? In both cases, particles are held together by attractions between opposite charges. The difference is that ionic charges are stronger

  28. Section 2: Properties of Water

  29. Objectives • Why are water molecules polar? • What are acidic solutions? What are basic solutions?

  30. The Big Idea • Much of our planet is covered in water • Water is necessary for life to exist • If life exists on other planets, there most likely is water present • Water has many properties that make life possible

  31. Polarity (-) The oxygen atom has a stronger attraction for electrons (+)

  32. Hydrogen Bonds • Because of waters partial charges, they can attract each other and create hydrogen bonds • Not as strong as covalent or ionic bonds • Waters ability to create multiple hydrogen bonds gives it many special properties

  33. Cohesion • Attraction between molecules of the same substance

  34. Adhesion • Attraction molecules of different substances

  35. Mixture • Material composed of two or more elements or compounds that are physically mixed but not chemically combined • Ex.) salt & pepper, earths atmosphere

  36. Solutions • Mixture of two or more substances in which the molecules are evenly distributed • Ex.) salt water • Settles out over time

  37. Cl- Cl- Na+ Na+ Water Water Solutions

  38. Solute • Substance that is dissolved • Ex.) salt

  39. Solvent • The substance that does the dissolving • Ex.) Water

  40. Suspensions • Mixture of water and non-dissolved materials • Ex.) sugar solution, blood • Separate into pieces so small, they never settle out

  41. The pH scale • Indicated the concentration of hydrogen ions in a solution

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