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Properties of Atoms

1. Properties of Atoms. 2. Atomic Structure Goals. SC3 Students will use the modern atomic theory to explain the characteristics of atoms. a. Discriminate between the relative size, charge, and position of protons, neutrons, and electrons in the atom.

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Properties of Atoms

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  1. 1 Properties of Atoms

  2. 2 Atomic Structure Goals SC3 Students will use the modern atomic theory to explain the characteristics of atoms. a. Discriminate between the relative size, charge, and position of protons, neutrons, and electrons in the atom. b. Use the orbital configuration of neutral atoms to explain its effect on the atom’s chemical properties. c. Explain the relationship of the proton number to the element’s identity. d. Explain the relationship of isotopes to the relative abundance of atoms of a particular element. e. Relate light emission and the movement of electrons to element identification.

  3. 4 This will be our FOCUS Matter Mixture Substance Element Compound

  4. 5 What is an Element? • One of the ~116 known “Pure”, un-cutable substances….that still retain the properties of that substance.

  5. 6 Clip What is an Atom? • Smallest piece of matter that still retains the properties of that matter. • What are they composed of?

  6. Timeline Bohr Model- electrons are found only in specific circular paths, or orbits, around the nucleus. Electron Cloud Model: Probable locations of electrons. MODERN: Quantum Mechanical Model: Mathematical model describing the behavior of electrons and energy of electrons in various locations around the nucleus.

  7. Atomic Structure 7 Subatomic Particles • Protons • Neutrons • Electrons Nucleus

  8. Atomic Structure 8

  9. 9 What makes one element different from another element? Number of protons. Atomic Structure

  10. Atomic Structure 10 Rutherford’s Gold Foil experiment led to the discovery of a positive nucleus.

  11. Atomic Structure 11 Protons • Positive Charge • The number of protons determines which element it is. • All elements have different numbers of protons • 1 amu • Composed of quarks

  12. Atomic Structure Neutron • Neural charge • Located in the nucleus • 1 amu • Composed of quarks

  13. Atomic Structure Electrons 12 • Smallest subatomic particle. • 1/1800 the mass of a proton. • Orbit nucleus. • Negative Charge

  14. Atomic Structure 13 • Electrons are found in different levels around the nucleus. • These are called Energy Levels or shells. • Each energy level also has “sublevels” or orbitals

  15. Atomic Structure 14

  16. Atomic Structure 15 Clip Electrons are found in the Electron cloud surrounding the nucleus.

  17. Atomic Structure 16 Each Energy Level Can Hold A Certain Number of Electrons! Only TWO on the first level!

  18. Atomic Structure 17 17 Different atoms have different numbers of electrons! Each Energy Level Can Hold A Certain Numbers of Electrons! Eight on the 2nd 2n2

  19. Atomic Structure 18

  20. Atomic Structure

  21. Atomic Structure 19 1 H • Atomic Number • Number of Protons • Atomic Mass • Sum of Protons & Neutrons 1 The # of Protons determines the identity of an element. All elements have different number of protons.

  22. 20 How can I find out how many electrons an atom has? • Atom= neutral • So, the number of protons = electrons. • Atomic number tells you the number of protons................. • So, it also tells you the number of electrons! Atomic Structure

  23. Practice with a friend…………

  24. Quantum Mechanical Model • Based on quantum theory, which says matter also has properties associated with waves. • According to quantum theory, it’s impossible to know the exact position and momentum of an electron at the same time. This is known as the Uncertainty Principle. • This model of the atom uses complex shapes of orbitals(sometimes called electron clouds) • Orbitals: volumes of space in which there is likely to be an electron. So, this model is based on probability rather than certainty.

  25. Atomic Orbitals • An atomic orbital is a region of space in which there is a high probability of finding an electron. • Energy levels of electrons are labeld by principal quantum numbers (n). • Each energy sublevel corresponds to an orbital of a different shape, which describes where the electron is likely to be found. • Different orbitals have different shapes.

  26. 21 Quantum Numbersn, l, m, s • Describing electron locations • 4 quantum number. • 1st-Principle Quantum # = n • Which energy level the e- is in. • n= 1-7 (there are only 7 energy levels) • Max # formula= 2n2 • the larger the value of n, the farther away from the nucleus and the higher the energy of the electron.

  27. 2nd quantum number= l • Describes the shape (orbital) • Shapes: s, p, d, f • Each shape “sublevel” can only have 2 electrons. • Max electrons in each sublevel: • s=(1x2)2, p=(3x2)6, d=(5x2)10, f=(7x2)14 # of sublevels

  28. s & p

  29. S (1),p (3), d (5) # of sublevels (shapes)

  30. F (7)

  31. 3rd quantum number= m • Describes orientation in space • x, y, z • 4th quantum number= s • Describes the spin of the e in the orbital • Clock or counterclock

  32. Brain Break • Clip

  33. 22 Orbital Filling Diagrams (3 rules) • Aufbau Principle: e- occupy orbitals of the lowest energy first. p.133 text

  34. 22 Orbital Filling Diagrams • Hund’s Rule: one electron in each orbital, then electrons pair up with opposite spins. • Pauli Exclusion Principal: An orbital may have no more than 2 electrons. 2 e- cannot have the same spin in the same orbital.

  35. 23 • Practice: • H, C, Na, S, Ar, K.

  36. We can use the periodic table to predict which sublevel is being filled by a particular element. Blocks and Sublevels

  37. 24 Electron Configuration Notation

  38. Practice: Write the electron configuration notation. NameAtomic NumberElectron Configuration • Oxygen 8 1s2 2s22p4 • Aluminum 13 1s2 2s22p63s23p1 • Chlorine 17 1s2 2s22p63s23p5 25

  39. 26

  40. 27 Electrons and Light Emission • When atoms absorb energy, electrons move into higher energy levels (excited state). • When the return to their ground state, the lose energy by emitting light. • The light emitted is a mixture of a specific frequencies.

  41. 28 • A quantum of energy is the amount of energy required to move an electron from on energy level to another energy level. • The higher the ground state, the less energy it take to move to a higher energy level.

  42. Electrons & Light Emission • Each frequency is a different color. • When the frequencies are passed through a prism, the colors are separated & an atomic emission spectrum is created for that element. 29 • Larger “jump”- more energy-more towards the blue side • Smaller “jump”- less energy-more towards the red side

  43. 30 • The flame test is used to visually determine the identity of an unknown metal or metalloid ion based on the characteristic color the salt turns the flame of a bunsen burner

  44. 31 Isotopes

  45. 32 Isotopes Isotopes are atoms that have the same number of protons and differonly in the number of neutrons. Most isotopes are stable but radioactive isotopes are unstable and break down into more stable forms byemitting particles and energy (radiation). Radiation can be detected, so radioactive isotopes are useful as labels in scientific research and medical diagnostic procedures.

  46. 33

  47. 34 28 Let’s Do some practice problems 

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