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Virtually everything that is, is made up of atoms.

Virtually everything that is, is made up of atoms. Atomic Structure. Chapter 12, page 361 Balloon and sweeter animation. Sub-Particles in the Atom. Each element is chemically unique. To understand why they are unique,

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Virtually everything that is, is made up of atoms.

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  1. Virtually everything that is, is made up of atoms. Atomic Structure Chapter 12, page 361 Balloon and sweeter animation

  2. Sub-Particles in the Atom Each element is chemically unique. To understand why they are unique, you need to know the structure of the atom (the smallest particle of an element) and the characteristics of its components. Element= made of one kind of Atom. Li Compounds= made of different atoms chemically bonded in whole number ratios. H2O •Mixtures are physical combinations of elements or compounds with variable composition O2 + H2. Particles or Pure substances

  3. Sub-Particles in the Atom atomic.mass.unit= a.m.u. ~ 1.992 ×10−27kg or 1/12 the mass of C-12

  4. Size of an atom • Atoms are incredibly tiny. • Measured in picometers(10-12 meters) • Hydrogen atom, 32 pm radius • Nucleus tiny compared to atom • Radius of the nucleus near 10-15 m. • Density near 1014 g/cm3 • IF the atom was the size of a stadium, the nucleus would be the size of a marble. California WEB

  5. What holds an atom together? • Nuclear Tug-Of-War • • Electrostatic force – like charges repel and un-like charges attract • Strong Nuclear Force – holds nucleons (p+ & n0) • together, very strong nuclear force but over short distances – Stable nuclei are SMALL – Large nuclei tend to be unstable (radioactive) • • Electrostatic Force • – Holds electrons on atom Balloon and sweeter animation

  6. 12 14 C C 6 6 Counting Particles in Atoms Atomic Number= number of protons (p+) = unique for each element Atomic Mass Number = Mass of an atom = number of protons + neutrons = (p+) + (no); (e- do not have mass) Mass Number = A C 12 6 Atomic Number = Z California WEB

  7. How can I remember how many protons or electrons there are? Just remember the A.P.E. rules! A P E • atomic number = • number of protons = • number of electrons

  8. Now, how do I remember how many protons there are? Just remember the M.A.N.! M A N • mass number - • Atomic number = • number of neutrons

  9. Neon Ne Protons: Electrons: Neutrons: Atomic Number: 10 Atomic Mass: 20 10 10 10

  10. Phosphorus P Protons: 15 Electrons: Neutrons: 16 Atomic Number: Atomic Mass: 15 15 31

  11. Aluminum Al Protons: Electrons: 13 Neutrons: 14 Atomic Number: Atomic Mass: 13 13 27

  12. Argon Ar Protons: 18 Electrons: Neutrons: Atomic Number: Atomic Mass: 40 18 22 18

  13. Silicon Si Protons: Electrons: Neutrons: 14 Atomic Number: 14 Atomic Mass: 14 14 28

  14. X Mass number # protons Atomic number # protons + # neutrons mass number Symbols Contain the symbol of the element, the mass number and the atomic number (top heavy)

  15. + F 19 9 Symbols • Find the • Atomic number • Mass number • number of electrons • number of protons • number of neutrons = 9 = 19 = 9 = 9 = 10

  16. So let’s practice!

  17. Br 80 35 Symbols Find the • number of protons • number of neutrons • number of electrons • Atomic number • Mass number = 35 = 45 = 35 = 35 = 80 http://www.chem.purdue.edu/gchelp/liquids/bromine.gif

  18. Symbols Find the • number of protons • number of neutrons • number of electrons • Atomic number • Mass number = 11 = 12 Na 23 = 11 = 11 11 = 23 Sodium atom

  19. Ions cation: a (+) ion • -- more p+ than e– -- formed when atoms lose e– To find net charge on an atom, consider the p+ and the e–. anion: a (–) ion -- more e– than p+ atoms -- formed when gain e– - • ion: a charged atom - - - - Ca+ion : loss of electrons + + - + + p+ p+ + + + + + + + + n0 n0 e- e- - - - - - - +3 and -2 = +1 +3 and -4 = -1

  20. Symbols Look Find the • number of protons • number of neutrons • number of electrons • Atomic number • Mass number = 11 Na 23 = 12 1+ = 10 11 = 11 = 23 Sodium ion

  21. V 51 23 Symbols If an element has an atomic number of 23 and a mass number of 51 what is the • number of protons • number of neutrons • number of electrons • Complete symbol = 23 = 28 = 23

  22. Nd 144 60 Symbols If an element has 60 protons and 84 neutrons what is the • Atomic number • Mass number • number of electrons • Complete symbol = 60 = 144 = 60

  23. Pt 195 78 Symbols If a neutral atom of an element has 78 electrons and 117 neutrons what is the • Atomic number • Mass number • number of protons • Complete symbol = 78 = 195 = 78

  24. + + + + + + Mass Number • mass number= protons + neutrons • always a whole number • NOT on the Periodic Table! Neutron Electrons Nucleus e- Proton Nucleus e- e- e- e- Carbon-12 Neutrons 6 Protons 6 Electrons 6 e-

  25. C 12 6 Mass # Atomic # Isotopes • Atoms of the same element with different mass numbers. • Nuclear symbol: • Hyphen notation: carbon-12 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  26. Isotopes • Dalton was wrong. • Atoms of the same element can have different numbers of neutrons. • different mass numbers. • called isotopes.

  27. Neutron Nucleus Proton Proton + Nucleus + Neutron + + + Carbon-12 + + + + + + + Carbon-14 Isotopes Electrons Nucleus Electrons Neutrons 6 Protons 6 Electrons 6 Neutrons 8 Protons 6 Electrons 6 Nucleus

  28. What is an isotope? same number of protons, different numbers of neutrons. Boron-10 B Protons: Electrons: Neutrons: Atomic Number: 5 Atomic Mass:10 Boron-11 B Protons: Electrons: Neutrons: Atomic Number: 5 Atomic Mass:11 B-10 10B 5 5 5 5 5 B-11 11B 5 5 6

  29. What is the average atomic mass of Carbon? 14 Carbon- C Protons: Electrons: Neutrons: 6 Atomic Number: 6 Atomic Mass: Carbon- C Protons: 6 Electrons: Neutrons: Atomic Number: Atomic Mass:14 12 6 6 6 8 6 12

  30. 37 Cl 17 Cl 37 17 Isotopes • Chlorine-37 • atomic #: • mass #: • # of protons: • # of electrons: • # of neutrons: • 17 • 37 • 17 • 17 • 20 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  31. Writing Isotopes • Put the mass number after the name of the element • carbon- 12 • carbon -14 • uranium-235 • Or C C 12 6 12 6 Mass # Atomic # California WEB

  32. Using a periodic table and what you know about atomic number, mass, isotopes, and electrons, fill in the chart: Atomic Number = Number of Protons Number of Protons + Number of Neutrons = Atomic Mass Atom (no charge) : Protons = Electrons Ion (cation) : Protons > Electrons Ion (anion) : Electrons > Protons

  33. Using a periodic table and what you know about atomic number, mass, isotopes, and electrons, fill in the chart: A N S W E R K E Y 16 0 O 8 Oxygen K 19 20 18 19 35 80 35 36 Bromine 30 35 0 Zn Zinc Atomic Number = Number of Protons Number of Protons + Number of Neutrons = Atomic Mass Atom (no charge) : Protons = Electrons Ion (cation) : Protons > Electrons Ion (anion) : Electrons > Protons

  34. Isotopes • Because of the existence of isotopes, the mass of a collection of atoms has an average value. • Average mass = ATOMIC WEIGHT = ATOMIC MASS • Boron is 20% B-10 and 80% B-11. • That is, B-11 is 80 percent abundant on earth. • For boron atomic mass = 0.20 (10 amu) + 0.80 (11 amu) = 10.8 amu

  35. Average Atomic Mass • massed average of all isotopeson the Periodic Table • round to 2 decimal places Avg. Atomic Mass (mass)(%) + (mass)(%) = 100 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  36. Average Atomic Mass • EX: Calculate the avg. atomic mass of oxygen if its abundance in nature is 99.76% O-16, 0.04% O-17, and 0.20% O-18. Avg. Atomic Mass (16)(99.76) + (17)(0.04) + (18)(0.20) 16.00 amu = = 100 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  37. Average Atomic Mass • EX: Find chlorine’s average atomic mass if approximately 8 of every 10 atoms are chlorine-35 and 2 are chlorine-37. Avg. Atomic Mass (35)(8) + (37)(2) = = 35.40 amu 10 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  38. 17 Cl 35.453 • Assume you have only two atoms of chlorine. • One atom has a mass of 35 amu (Cl-35) • The other atom has a mass of 36 amu (Cl-36) • What is the average mass of these two isotopes? 35.5 amu • Looking at the average atomic mass printed on the periodic table...approximately what percentage is Cl-35 and Cl-36? 55% Cl-35 and 45% Cl-36 is a good approximation

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