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Atomic Structure Ch. 5.1 & 5.2

Atomic Structure Ch. 5.1 & 5.2. Gotta start somewhere. Let ’ s go backward in order to go forward. What was that all about?. To study atoms and their interactions, we need to revisit something we studied earlier this year Matter and mass. Matter and Mass.

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Atomic Structure Ch. 5.1 & 5.2

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  1. Atomic StructureCh. 5.1 & 5.2

  2. Gotta start somewhere • Let’s go backward in order to go forward What was that all about? • To study atoms and their interactions, we need to revisit something we studied earlier this year • Matter and mass

  3. Matter and Mass • Matter - Everything in universe is composed of matter • anything that occupies space and has mass • Mass – quantity of matter an object has

  4. So matter is made of… • ELEMENTS! • Pure substances that cannot be broken down chemically into simpler kinds of matter • More than 100 elements (92 naturally occurring) • About25of the 92 natural elements are essential to life

  5. So matter is made of… • ELEMENTS! • Pure substances that cannot be broken down chemically into simpler matter • More than 100 elements (92 naturally occurring) • About 25 of the 92 natural elements are essential to life

  6. What about the rest of them? Many used for new technology Platinum: Catalytic converters, fuel cells, electrodes Indium: Solar panels Gallium: LED’s, laser diodes, photodetectors Tantalum: Microchips, new technologies

  7. ATOMS • The simplest particle of an element that retains all the properties of that element • Atoms of each element of have unique properties that determine how that element behaves during chemical reactions

  8. What do we know about ATOMS? • Dalton’s Atomic Theory summarizes the key ideas • 1. All elements are composed of tiny indivisible particles called atoms* • 2. Atoms of the same element are identical. Each element is made of one type of atom.

  9. What do we know about ATOMS? • Dalton’s Atomic Theory summarizes the key ideas • 3. Atoms of different elements can mix together physically or chemically combine to make compounds • 4. Chemical reactions occur when atoms are separated, joined or rearranged. Atoms of one element are never changed into atoms of another element.

  10. How big (or small) is an atom? • Cell Size and Scale – University of Utah Genetics If a penny was made of pure copper, there would be approximately 2.4x1022 atoms in that one coin. 100 million copper atoms lined up in a row would cover 1 cm of distance

  11. How big (or small) is an atom? • A typical human hair is approximately 1 million carbon atoms wide 100x magnification 400x magnification

  12. Is it possible to see atoms? • Yes, with very advanced microscopes • STM – Scanning Tunneling Microscope • Pb atoms on silicon surface • “The STM works by scanning a very sharp metal wire tip over a surface. By bringing the tip very close to the surface, and by applying an electrical voltage to the tip or sample, we can image the surface at an extremely small scale – down to resolving individual atoms.” Nanoscienceinstruments.com

  13. Atomic Structure • Three particles make up atoms • Protons - Mass of 1 amu, Charge of +1 • Neutrons – Mass of 1 amu, No charge (neutral) • Electrons – No mass, Charge of -1

  14. Atomic Structure • Three particles make up atoms • Protons - Mass of 1 amu, Charge of +1 • Neutrons – Mass of 1 amu, No charge (neutral) • Electrons – No mass, Charge of -1 • Atoms have two regions: The nucleus in the center, and The outer energy levels • Protons and Neutrons are found in the nucleus, Electrons are found in the outer energy levels

  15. Atomic Structure Diagram of a Carbon Atom Nucleus Energy Levels

  16. Atomic Structure

  17. Atom Terminology • The Atomic Number for an element is the number of protons in an atom of that element. • Hydrogen atoms all have one proton, so the Atomic Number for Hydrogen is 1 • Atoms with different atomic numbers will be from different elements

  18. Atom Terminology • Mass number is the total number of protons and neutrons in an atom • # of neutrons = mass number – # of protons (atomic number)

  19. Terminology Continued • Isotopes: Atoms of the same element that have different numbers of neutrons

  20. Atoms Atoms of the same element that vary in the number of ___________ (atomic # same, atomic mass varies) neutrons • Isotopes

  21. Isotopes 1 H 1 2 H 1 3 H 1 99.98% 0.015% trace Potassium in a banana: 39K (93.25%), 40K (6.7302%) and 41K (0.0117%) Atomic # 19 19p 20n 19e 19p 21n 19e 19p 22n 19e

  22. Why do atomic masses (mass #) have decimal places? • Most elements exist as mixtures of two or more isotopes. • Atomic mass is the average mass of all of the isotopes of given element. Determine the Mass # of Carbon 12.011 C 6 • C-12 98.89% • C-13 1.11% • C-14 trace 12 x .9889 = 11.8668 13 x .0111= 0.1443 + 12.0111

  23. The Electrons • Travel at very high speeds at various distances (energy levels) from the nucleus • Electrons in the same energy level are approximately the same distance from the nucleus • Outer energy levels have more energy than inner levels • Each level holds only a certain number of electrons Remember 2 8 8 !

  24. Atoms 1 H 1 1P 0N 1e Subatomic Particles • Protons • Neutrons • Electrons Drawing Atoms • Atomic # • Atomic Mass (Mass #) 12 C 6 9P 10N 6P 6N 19 F 9 2e 7e 2e 4e

  25. Draw These Atoms 16 O 8 7 Li 3 3P 4N 8P 8N 2e 2e 6e 1e 31 P 15 15P 16N 2e 8e 5e

  26. Periodic Table • Elements arranged on a periodic table by their atomic numbers 1 2 4 3 5 6 7 8

  27. Periodic Table Tells the number of outermost electrons Family Period Tells the number of energy levels # of outermost electrons 1 2 3 4 5 6 7 8

  28. Compounds • Most elements do not exist by themselves • Readily combine with other elements in a predictable fashion • Compound • Pure substance made up of atoms of two or more elements • Proportion of atoms are always fixed • Ionic or covalently bonded • Chemical formula: the kind and proportion of atoms of each element in a compound • EX: H2O H2O

  29. Molecules: two or more elements covalently bonded (the elements can be the same (O2) or different (CO2) Let’s welcome our friend… Atoms of different elements Blue: Carbon Red: Oxygen Gray: Hydrogen GLUCOSE! SAME!

  30. Molecule • The simplest part of a substance that retains all of the properties of the substance and exists in a free state • Some can be very LARGE and COMPLEX

  31. Key Difference Between Molecules and Compounds • Compounds: Made of two or more different types of atoms • Molecules: Made of the same or different types of atoms

  32. Chemical Formulas 6CO2 + 6H2O C6H12O6 + 6O2 When have we seen this before? What are the pieces? What exactly is this formula telling us?

  33. Chemical equations represent chemical reactions coefficient • A ____________ represents the number of molecules involved in the reaction • A _____________represents the number of atoms in each molecule 2H2O subscript 2H2O

  34. Chemical Formulas 6CO2 + 6H2O C6H12O6 + 6O2 How many atoms of carbon are in a molecule of glucose? (subscript) How many water molecules are necessary to make a molecule of glucose? (coefficient) 6 6

  35. Chemical equations represent chemical reactions • Chemical Reactions: Atoms in an existing substance are rearranged to form a new substance. • Chemical bonds in the reactants are broken, and new bonds are formed to make the products. • A Chemical Equation represents the chemical reaction that converts the original substances (original forms of matter) into new substances (new forms of matter) 2H2 + 022H2O Products Reactants

  36. Chemical equations represent chemical reactions • A Chemical Equation represents the chemical reaction that converts the original substances (original forms of matter) into new substances (new forms of matter) 6CO2 + 6H2O C6H12O6 + 6O2 Reactants Products • The number of each kind of atom must be the same in both the reactants and products

  37. Chemical Bonds • An attraction between atoms that forms as a result of the sharing or complete transfer of electrons. Atoms tend to react (combine) with other atoms in order to become more stable (undergo chemical reactions) Stability = full outer electron level

  38. What about the family farthest to the right? The noble gases have a full outer electron shell and thus do not want to react with other elements. They are stable!

  39. Ionic Bonds • Some atoms become stable by becoming ions--- losing or gaining electrons • Atoms that lose electrons are called positive ions _____________ • Atoms that gain electrons are called negative ions __________ cations anions

  40. Because positive and negative electrical charges attract each other ionic bonds form Other ionic compounds: CaCl2 KBr MgF2

  41. Emergent property: Characteristic of a system not observed in any of its individual components. • The physical and chemical properties of a compound differ from the physical and chemical properties of the individual elements that compose it Sodium- soft, silvery white, highly reactive metal Will Kill You Chlorine- yellowish green , non metal, gas Will Kill You Sodium Chloride- Table Salt YUM Other example Example of emergent properties

  42. Halogens Chalcogens Nobel Gases Alkaline Earth Metals Alkali Metals

  43. Covalent Bonds • Formed when two atoms share one or more pairs of electrons • Octet Rule

  44. Covalent v. Ionic Bonds

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