Atomic Theory and Structure - PowerPoint PPT Presentation

About This Presentation
Title:

Atomic Theory and Structure

Description:

Atomic Theory and Structure Chapters 4-5 – PowerPoint PPT presentation

Number of Views:303
Avg rating:3.0/5.0
Slides: 50
Provided by: tcsd
Category:

less

Transcript and Presenter's Notes

Title: Atomic Theory and Structure


1
Atomic Theory and Structure
  • Chapters 4-5

2
Atomic Theories
  • Democritus 400 BC
  • believed that atoms were indivisible and
    indestructible
  • Dalton 1800s
  • Developed through experiments
  • First Atomic Model

3
Daltons Atomic Model
  • All elements are composed of tiny indivisible
    particles called atoms
  • Atoms of the same element are identical. The
    atoms of any one element are different from those
    of any other element.

4
Daltons Atomic Model (cont)
  • Atoms of different elements can physically mix
    together or can chemically combine in simple
    whole-number ratios to form compounds.
  • Chemical reactions occur when atoms are
    separated, joined, or rearranged. Atoms of one
    element, however, are never changed into atoms of
    another element as a result of a chemical
    reaction.

5
Discovery of Electron
  • 1897 JJ Thomson, using cathode ray tube,
    discovered negatively charged particles called
    electrons
  • 1909 Robert Millikan - Oil Drop Experiment
  • Determined charge on an electron.

6
Plum Pudding Model
  • Uniform positive sphere with negatively charged
    electrons embedded within.

7
Radiation
  • Late 1800s discovery of radiation
  • Three Types
  • Alpha
  • Beta
  • Gamma

8
Rutherford Gold Foil Experiment - 1909
  • Shot alpha particles at gold foil
  • Most went through foil with little or no
    deflection.
  • Some were deflected at large angle and some
    straight back.
  • A.K.A. Geiger Marsden Experiment

9
Rutherford Gold Foil Experiment - 1909
10
Rutherford Model
  • Conclusions from Gold Foil Experiment
  • Atom is Mostly Empty Space
  • Dense positive nucleus
  • Electrons moving randomly around nucleus

11
Subatomic Particles
  • Electron
  • Discovered in 1897 by JJ Thomson
  • Negative charge (-1)
  • Mass 9.10938910-28g
  • Approx mass 0
  • Found outside of nucleus

12
Subatomic Particles
  • Proton
  • Discovered in 1919 by Rutherford
  • Positive charge (1)
  • Mass 1.67262310-24g
  • Approx mass 1 atomic mass unit (u)
  • Found inside nucleus

13
Subatomic Particles
  • Neutron
  • Discovered in 1932 by James Chadwick
  • No charge (0)
  • Mass 1.674928610-24g
  • Approx mass 1 atomic mass unit (u)
  • Just slightly larger than a proton
  • Found inside nucleus

14
Atomic Structure
  • Atoms have no net charge
  • of electrons of protons
  • of electrons around nucleus of protons in
    nucleus

15
Atomic Structure
  • Atomic Number
  • Number of protons in an element
  • All atoms of the same element have the same
    number of protons
  • Mass Number
  • Number of protons and neutrons in an atom

16
Atomic Structure
  • of Neutrons Mass Number Atomic Number
  • Atoms of the same elements can have different
    numbers of neutrons
  • Isotope atoms of the same element with
    different number of neutrons

17
Chemical Symbols
Mass Number
  • Cl-35
  • Chlorine-35

Atomic Number
18
Ion
  • Atom or group of atoms that have gained or lost
    one or more electrons
  • Have a charge
  • Example
  • H, Ca2, Cl-, OH-

19
Ions
  • H 1 proton 0 electrons
  • Ca2 20 protons 18 electrons
  • Cl- 17 protons 18 electrons
  • OH- 9 protons 10 electrons

20
(No Transcript)
21
Atomic Theories
  • Rutherfords model could not explain the
    chemical properties of elements
  • Niels Bohr believed Rutherfords model needed to
    be improved
  • Bohr proposed that electrons are found only in
    circular paths around the nucleus

22
Bohr Model
  • Dense positive nucleus
  • Electrons in specified circular paths, called
    energy levels
  • These energy levels gave results in agreement
    with experiments for the hydrogen atom.

23
Bohr Model
24
Bohr Model
  • Each energy level can only hold up to a certain
    number of electrons
  • Level 1 ? 2 electrons
  • Level 2 ? 8 electrons
  • Level 3 ? 18 electrons
  • Level 4 ? 32 electrons

25
Electron Configuration
  • The way in which electrons are arranged in the
    atom
  • Example Na 2-8-1
  • Valence Electrons
  • Electrons in the outermost energy level

26
Energy Level Transitions
  • Electron energy is quantized
  • Electrons can move between energy levels with
    gains or losses of specific amounts of energy.

27
Energy Level Transitions
  • Gaining energy will move an electron outward to a
    higher energy level (Absorption)
  • When an electron falls inward to a lower energy
    level, it releases a certain amount of energy as
    light (Emission)

28
Energy Level Transitions
29
Ground State vs. Excited State
  • Ground State
  • When the electrons are in the lowest available
    energy level
  • Ex Na 2-8-1
  • Excited State
  • When one or more electrons are not in the lowest
    available energy level
  • Ex Na 2-7-2 or 2-8-0-1 or 2-6-1-1-1

30
Line Spectra
  • Emission Spectra
  • Shows only the light that is emitted from an
    electron transition
  • Absorption Spectra
  • Shows a continuous color with certain wavelengths
    of light missing (absorbed)

31
Energy Level Transitions
32
Energy Level Transitions
33
Wave Mechanical Model
  • More detailed view of the Bohr Model
  • Schrödinger Wave Equation and Heisenberg
    Uncertainty provides region of high probability
    where electron COULD be.
  • Orbital
  • Modern Model
  • AKA Quantum Mechanical Model, Electron Cloud Model

34
Wave Mechanical Model
  • Orbital
  • Regions of space where there is a high
    probability of finding an electron

35
Wave Mechanical Model
  • Each energy level is divided into sublevels
  • 1st Energy level has 1 sublevel, s
  • 2nd Energy level has 2 sublevels, s and p
  • 3rd Energy level has 3 sublevels, s, p, and d
  • 4th Energy level has 4 sublevels, s, p, d, and f
  • These sublevels start to overlap as you move away
    from the nucleus

36
Wave Mechanical Model
  • Sublevels are divided into orbitals
  • s sublevel has 1 orbital
  • p sublevel has 3 orbitals
  • d sublevel has 5 orbitals
  • f sublevel has 7 orbitals
  • Each orbital can hold up to 2 electrons

37
Atomic Orbitals
38
Electron Orbital Configuration
  • Sublevel order
  • 1s
  • 2s 2p
  • 3s 3p 3d
  • 4s 4p 4d 4f
  • 5s 5p 5d 5f 5g
  • 6s 6p 6d 6f 6g 6h
  • 7s 7p 7d 7f 7g 7h

39
Electron Orbital Configuration
  • One sublevel must be full before you can move to
    the next sublevel
  • For sublevels with multiple orbitals
  • Each orbital must have one electron before you
    can double up

40
Electron Orbital Configuration
  • H ____ 1s1
  • He ____ 1s2
  • Li ____ ____ 1s2 2s1

1s
1s
1s
2s
41
Electron Orbital Configuration
  • C ____ ____ ____ ____ ____
  • C 1s2 2s22p2
  • N ____ ____ ____ ____ ____
  • N 1s2 2s22p3

1s
2s
2p
1s
2s
2p
42
Electron Orbital Configuration
  • O ____ ____ ____ ____ ____
  • O 1s2 2s22p4
  • F ____ ____ ____ ____ ____
  • F 1s2 2s22p5

1s
2s
2p
1s
2s
2p
43
(No Transcript)
44
MMs Demo
  • What colors are found in a regular MMs bag?
  • Green
  • Yellow
  • Orange
  • Blue
  • Red
  • Brown

45
MMs Demo
  • Do you get an equal amount of each color in each
    bag?
  • If we opened up all the regular MM bags in the
    world would we get an equal number of each color?
  • Are you supposed to?

46
MMs Demo
Color 1 bag World
Blue 24
Green 16
Yellow 14
Orange 20
Red 13
Brown 13
47
MMs Demo
  • MMs come in certain abundances (percentages)
  • So do isotopes of each element
  • Relative Abundance
  • Percent of each naturally occurring isotope found
    in nature

48
Average Atomic Mass
  • Atomic Mass
  • Weighted average based on the relative abundance
    and mass number for all naturally occurring
    isotopes
  • Example
  • C-12 98.9 12.011u
  • C-13 1.1

49
Atomic Mass
  • C-12 98.9
  • C-13 1.1
  • Carbon 0.98912 0.01113 12.011u
Write a Comment
User Comments (0)
About PowerShow.com