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Chemistry I Chapter 3 Introduction to Atoms

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Title: Chemistry I Chapter 3 Introduction to Atoms


1
Chemistry I Chapter 3Introduction to Atoms
2
How small is an atom?
  • http//micro.magnet.fsu.edu/primer/java/scienceopt
    icsu/powersof10/

3
Atoms
4
Atoms vs. Hyle
  • Atom - the smallest particle of an element. It
    can exist alone, or combined with other atoms.
  • Atoms were first suggested by Democritus (Greek
    philosopher, 400B.C.).
  • People that supported Democritus view were called
    Atomists.
  • Aristotle(300B.C.) did not support the idea of
    atoms. He believed that all matter was a
    continuous substance called hyle. Hyle was
    composed of earth, air, fire and water.

5
Democritus vs. Aristotle
6
John Dalton.THE MAN!
  • John Dalton-(English school teacher) first to
    explain the existence of atoms and disspelling
    Aristotles theory of matter.

7
John Dalton
  • Formulates Atomic Theory
  • Each element is made up of tiny indivisible
    particles called atoms.
  • The atoms of a given element are identical, atoms
    of different elements are different.
  • Chemical compounds are formed when atoms come
    together, in simple whole number ratios.
  • Chemical reactions involve the reorganization of
    the atoms combined, separated or rearranged.

8
1903 J.J. THOMSON
  • Discovers the electron, using his famous Cathode
    Ray Tube (CRT), which turns out to be a primitive
    TV or computer monitor.

9
Discovery of the Electron
In 1897, J.J. Thomson used a cathode ray tube to
deduce the presence of a negatively charged
particle, the electron.
Cathode ray tubes pass electricity through a gas
that is contained at a very low pressure.
10
CRT and TV
11
1911 Ernest Rutherford
  • Rutherford discovers the nucleus of an atom,
    using his famous gold foil experiment.

12
Rutherfords Gold Foil Experiment
13
Rutherfords Gold Foil Experiment
14
Rutherfords Gold Foil Experiment
  • Alpha (?) particles are helium nuclei
  • Particles were fired at a thin sheet of gold
    foil
  • Particle hits on the detecting screen (film) are
    recorded

15
Rutherfords Gold Foil Experiment
16
How big is an atom?
17
Characteristics of sub-atomic particles
  • Particle symbol charge location mass
  • Proton p 1 nucleus 1 amu
  • Neutron no 0 nucleus 1 amu
  • Electron e- -1 orbital 1/1840 amu
  • amu atomic mass unit, unit used to mass very
  • small objects. (1 amu 1/12 the mass
    of a
  • carbon-12
    nucleus)
  • Orbital the 3-dimensional space around the
    nucleus of an atom, where electrons are found
    most of the time.

18
Atomic Structure
19
Atomic Models
  • JJ Thomson model(Plum pudding model) electrons
    are scattered throughout the atom, like raisins
    in plum pudding.
  • Rutherford Model-The atom has a central dense
    core, but is mostly empty space.
  • Bohr Model(Planetary model)Electrons orbit the
    nucleus in circular paths, called energy levels
  • Quantum Model (Modern, Shrodinger model)-
    Electrons move randomly in spaces called
    orbitals, around the nucleus.

20
Thomsons Atomic Model
Thomson believed that the electrons were like
plums embedded in a positively charged pudding,
thus it was called the plum pudding model.
21
Rutherfords Findings
  • Most of the particles passed right through
  • A few particles were deflected
  • VERY FEW were greatly deflected

Like howitzer shells bouncing off of tissue
paper!
Conclusions
  • The nucleus is small
  • The nucleus is dense
  • The nucleus is positively charged

22
The Bohr Model of the Atom
I pictured electrons orbiting the nucleus much
like planets orbiting the sun.
But I was wrong! Theyre more like bees around a
hive.
Neils Bohr
23
Quantum MechanicalModel of the Atom
Mathematical laws can identify the regions
outside of the nucleus where electrons are most
likely to be found.
24
Important definitions about atoms
  • atomic number number of protons in the nucleus
    of an atom. The number of protons determines the
    element of an atom.
  • atomic mass number mass of the atom in amu, it
    includes the number of protons and neutrons.
  • (electrons are not counted)
  • Isotopes atoms of the same element, with a
    different number of neutrons in the nucleus.
    Isotopes of each element have the same atomic
    number, but different mass numbers.

25
TAKS QUESTION
26
Isotopes
27
Boron isotopes
28
(No Transcript)
29
Find the number of protons, neutrons and
electrons in each
  1. Carbon-14
  2. Nitrogen-15
  3. U-235
  4. Hydrogen-3
  5. Carbon-13
  6. Helium-3
  7. B-11
  8. Cu-64

30
Periodic Table Families
31
List the Element Family
  • Element Family Element Family
  • Br Fe
  • K U
  • Sr Si
  • Ce C
  • Ar Cs

32
  • Orbital- the 3-d space around the nucleus of an
    atom where an electron is found most of the time.
    Each orbital can hold up to 2 electrons of
    opposite spin.

33
Orbitals have different shapes
  • Orbital shape
  • s spherical
  • p dumbbell
  • d clover or
  • dumbbell/donut
  • f too complex

34
Energy sublevels around an atom
  • energy electron
  • sublevels of orbitals capacity
  • s 1 2
  • p 3 6
  • d 5 10
  • f 7 14
  • g 9 18
  • orbitals exist, but not used most of the time.

35
Aufbau Order- Energy levels orbital types
around the atom
  • Aufbau order- Electrons fill orbitals closest to
    the nucleus first.
  • 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p,6s,
    4f, 5d, 6p, 7s, 5f, 6d, 7p

36
Orbital notation
37
Electron configuration
38
Valence Electrons/Lewis Dot Notation
39
How to calculate average atomic mass
40
Pre AP Chemistry Nuclear Equations
  • Nuclear Reactions(transmutation reactions) are
    represented with Nuclear Equations.
  • Transmutation reactions a reaction where one
    nucleus changes element.
  • ( of protons)

41
Nuclear equations
  • See board

42
Half-life the amount of time it takes for ½ of
a sample to react or decay.
  • The half life of Ti-48 is 47 hrs. How much of a
    250 gram sample remains after 94 hrs?
  • A 100gram sample of Cd-114 decays until only 12.5
    grams remain in a total of 41years. What is the
    half-life for this isotope?

43
TAKS QUESTION
44
Electron orbitals
  • Orbital a 3-dimensional space around the
    nucleus which can hold up to 2 electrons, with
    opposite spin.
  • electrons are found in their orbitals 99.9 of
    the time.
  • Orbitals have different shapes s, p, d, f

45
Orbitals have different shapes
  • Orbital shape
  • s spherical
  • p dumbbell
  • d clover or
  • dumbbell/donut
  • f too complex

46
s-orbitals spheres
47
p-orbitals dumbbell
48
d-orbitals clover (double dumbbell) or
dumbbell/donut
49
f-orbitals complex
50
Energy sublevels around an atom
  • energy electron
  • sublevels of orbitals capacity
  • s 1 2
  • p 3 6
  • d 5 10
  • f 7 14
  • g 9 18
  • orbitals exist, but not used most of the time.

51
Orbital Notation
  • Aufbau Order
  • (Nucleus)1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d,
    5p, 6s, 4f, 5d, 6p, 7s, 5f
  • This is the order in which electrons
    fill!!!!!
  • You must learn the order!! Dont worry there is
    always an easier way to memorize these things.
    For the Aufbau Order there are 2 ways With
    arrows or with the periodic table! Smartboard
    activate!

52
Electron Configurations and the Periodic Table
Figure 8.7
53
Orbital Notation
  • Write the orbital notation for each atom
  • Nitrogen, N(7 electrons)
  • Sodium, Na(11 e-)
  • Iron, Fe(__ e-)
  • Antimony, Sb(__ e-)
  • Gold, Au(__ e-)
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