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The Chemistry of Life: Atoms, Ions, and Molecules

This chapter explores the fundamental concepts of atoms, ions, and molecules in the chemistry of life. It covers subatomic particles, chemical bonds, isotopes, and the electron cloud model. Learn how these concepts are essential to understanding the chemistry that sustains life.

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The Chemistry of Life: Atoms, Ions, and Molecules

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  1. Chapter 2 The Chemistry of Life

  2. Section 1: Atoms, Ions, and Molecules

  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. DALTON’S ATOMIC THEORY Dalton performed experiments, unlike Democritus, to test his theory on atomic structure. Theory included the following ideas: All elements are composed of submicroscopic indivisible particles called atoms. Atoms of the same element are identical. Atoms of different elements can physically mix together or chemically combine with one another in whole-number ratios to form compounds. Chemical reactions occur when atoms are separated, joined, or rearranged.

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

  9. What are the 3 major parts of an atom? • Proton • Neutron • Electron

  10. Describe Proton • Protons are positively charged particles found in the atomic nucleus. Protons were discovered by Ernest Rutherford.. • Experiments done in the late 1960's and early 1970's showed that protons are made from other particles called quarks. Protons are made from two 'up' quarks and one 'down' quark.

  11. Describe Neutron • Neutrons are uncharged particles found in the atomic nucleus. Neutrons were discovered by James Chadwick in 1932. • Experiments done in the late 1960's and early 1970's showed that neutrons are made from other particles called quarks. Neutrons are made from one 'up' quark and two 'down' quarks.

  12. Describe Electron • Electrons are negatively charged particles that surround the atom's nucleus. Electrons were discovered by J. J. Thomson in 1897. • Electrons determine properties of the atom. Chemical reactions involve sharing or exchanging electrons.

  13. Describe nucleus • The nucleus is the central part of an atom. It is composed of protons and neutrons. • The nucleus contains most of an atom's mass. • It was discovered by Ernest Rutherford in 1911.

  14. Describe Quark • Believed to be one of the basic building blocks of matter. Quarks were first discovered in experiments done in the late 1960's and early 1970's. • Three families of quarks are known to exist. Each family contains two quarks. The first family consists of Up and Down quarks, the quarks that join together to form protons and neutrons. • The second family consists of Strange and Charm quarks and only exist at high energies. • The third family consists of Top and Bottom quarks and only exist at very high energies.

  15. Describe isotope • Atoms that have the same number of protons but different numbers of neutrons

  16. What is the Electron Cloud Model? • Model of the atom pictures the electrons moving around the nucleus in a region called an electron cloud. • The electron cloud is a cloud of varying density surrounding the nucleus. The varying density shows where an electron is more or less likely to be. Atoms with electrons in higher energy levels have additional electron clouds of different shapes that also show where those electrons are likely to be. For more information, click here: http://regentsprep.org/Regents/physics/phys05/catomodel/cloud.htm

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

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

  19. 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

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

  21. The weighted average of the masses of an elements isotope is called its atomic mass

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

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

  24. Table Salt

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

  26. 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

  27. If an atom loses an electron it becomes positive • If an atom gains an electron it becomes negative

  28. Ions • Positively and negatively charged atoms

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

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

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

  32. Homework

  33. Describe the structure of an atom. • Why do all isotopes of an element have the same chemical properties? • What is a covalent bond? • What is a compound? How are they related to molecules? • How do Van der Waals forces hold molecules together? • How are ionic bonds and Van der Waals forces similar? How are they different?

  34. Section 2: Properties of Water

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

  36. 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

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

  38. 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

  39. Cohesion • Attraction between molecules of the same substance

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