Atoms

1
Atoms

• What are we going to study about the atom?
• History
• Structure
• Properties
• Forces

2
Atomic Structure

• What is an atom composed of?
• 2. What subparticle(s) are responsible for an
  atoms charge?
• 3. What subparticle(s) are responsible for an
  atoms mass?
• 4. Illustrate an atom, identifying the
  subparticles and their location within the atom.

3
Atomic Structure
Subatomic Particle symbol charge Mass (g) mass (amu)
proton p 1 1.674 x 10 -24 1
electron e- - 1 9.11 x 10-28 0
neutron n0 0 1.675 x 10 -24 1
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Distinguishing Atoms

• Draw the atom below and identify the following
  electrons, protons, neutrons, electron cloud,
  nucleus, and energy levels.
• 2.What distinguishes one elements atom from
  another elements atom?

education.jlab.org
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What distinguishes each element below from one
another?
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Distinguishing Atoms
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Distinguishing Atoms

• Atomic number
• The number of protons within an atoms nucleus.
• An atoms I.D.
• Atoms of the same element always have the same
  number of protons.
• What do you notice about the atomic numbers on
  the periodic table?

8
An Atoms Mass

• Mass number
• The mass of a single atom.
• Sum of the p and n0 within an atom.
• Unit atomic mass unit (amu)
• The mass number is NOT the same as Atomic Mass

9
Atomic Structure
Subatomic Particle symbol charge Mass (g) mass (amu)
proton p 1 1.674 x 10 -24 1
electron e- - 1 9.11 x 10-28 0
neutron n0 0 1.675 x 10 -24 1
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Elements Subatomic Differences
Element Atomic Symbol Atomic Number Mass (amu) of p of n0 of e-



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Neutral Atoms

• Most matter in nature is neutral.
• (Doesnt shock us!)
• This means the atoms making up the matter is
  neutral. ?
• What are the two charged subatomic particles?
• p and e-
• For an atom to be neutral the of p of
  e-.

12
Elements Quiz

• When Thursday
• What First 20 elements on the periodic table.
• Know symbols and names

13
Atoms

• What are we going to study about the atom?
• History
• Structure
• Properties
• Forces

14
Isotopes

• What is an isotope?
• Atoms of the same element that have different
  number of neutrons.
• Also have different number of neutrons.

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Common Isotopes of Carbon
C-12
C-13 of p, n0, e-? of p,
n0, e-?
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Atomic Structure
History, Structure and Properties of the Atom
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Quiz History of the Atom

• Who is given credit for the earliest model of the
  atom?
• Explain Thomsons Plum Pudding model of the atom.
• What did Rutherfords model contribute to the
  atom?
• What did Bohrs model contribute to the atom?

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History of the Atom

• Great Thinkers (2,000yrs. Ago)
• Age of Reason and Thought
• Democritus vs. Aristotle view on the make-up of
  matter.

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Democritus(400b.c.)Greek Philosopher

• 1) Observed matter to be made up of atoms.
• 2) Atoms are the smallest form of matter.
• 3. Atoms cannot be broken down.
• 3) The types of atoms in matter determine its
  properties.

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Aristotle Greek Philosopher (300b.c.)

• Aristotle observed matter to be made from
  four things
• air, earth, fire and water.

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John Daltons Atomic Model
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Daltons Atomic Theory

• Atoms are the building blocks of all matter.
• Atoms cannot be subdivided.
• Each element has the same kind of atoms.
• In a compound, the different atoms chemically
  combine in the same way (fixed composition).
• Atoms cannot be created or destroyed just
  rearranged.

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John Daltons Atomic Model

• English school teacher
• Proved Democritus atoms hypothesis using the
  scientific method.
• His conclusions produced
• Daltons Atomic Theory

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Thomsons Plum Pudding Model
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Thomsons Cathode Tube Experiment
l-esperimento-piu-bello-della-fisica.bo.imm.c...
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Subatomic Particle Electron

• J.J. Thomson (pg. 105)
• 1897 discovered electrons in gas atoms using a
  cathode ray tube.
• Determined electrons have a negative charge.
• Electrons have the same charge in all atoms.
• Robert Millikan Determined the mass of the
  electron to be very tiny.

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J. J Thomsons Plum Pudding Model

• If atoms are made of electrons how come most
  matter does not shock us?
• Atoms must have positive particles, too.
• He proposed the Plum Pudding Atomic Model

An atom is equally made up of positive and
negative particles.
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Goldsteins Cathode Tube Experiment
chemed.chem.purdue.edu
reich-chemistry.wikispaces.com
He discovered protons using a cathode ray tube.
Observe particles moving in the opposite
direction.
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Subatomic Particles Protons

• 1886 Eugen Goldstein observed particles traveling
  in the opposite direction of the cathode
  rays(electrons).
• He knew these particles must be () charged.
  They were called protons.
• Protons charge is the same for all atoms
• Protons have a significant mass compared to the
  electron.

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Rutherfords Model of the Atom
green-planet-solar-energy.com
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Rutherfords Gold Foil Experiment
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Rutherfords Conclusion

• Most of the atom is empty space.
• Small dense region composed of
• () charged particles.
• (Nucleus)

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Rutherfords Nuclear Atom Model

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Subatomic Particle Neutron

• What keeps the protons within the nucleus ?
• (Like particles repel each other)
• 1932 - James Chadwick discovers that the nucleus
  also has neutral particles present. He called
  them neutrons.

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Chadwicks Experiments Neutron
nobelprize.org
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Bohrs Model of the Atom
http//micro.magnet.fsu.edu/
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Bohrs Model of the Atom
http//micro.magnet.fsu.edu/
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Current Atomic Model
Erwin Schrodinger
blogs.stsci.edu
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Current Atomic Model
Erwin Schrodinger
blogs.stsci.edu
science.howstuffworks.com
40
Current Atomic Model
Erwin Schrodinger
blogs.stsci.edu
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Types of electron paths around nucleus
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GenChem Infinite Campus Update

• Corrections to Measurement and Matter Exam
• Subatomic Structure Worksheet (10pts.)
• History of Atom Quiz (4pts.)

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preAPChem Infinite Campus Update

• Corrections to Measurement and Matter
• Subatomic Structure Worksheet (10pts.)
• History of Atom Quiz (4pts.)
• Atomic Structure Quiz (20pts.)

44
Bell Ringer History of Atom
Atomic Model Illustration Description
Daltons Model
Thomsons Model
Rutherfords Model
Bohrs Model
Schrodingers Model (current model)
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Isotopes and Atomic Mass

• What is an isotope?
• What does an isotope notation tell you?
• An elements isotopes are used to calculate the
  atomic mass of an element.

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Isotopes and Atomic Mass

• Atomic mass
• The average mass of all the elements isotopes
  present within a naturally occurring sample of
  matter.
• Weighted average mass. (unequal distribution of
  isotopes in sample of matter)
• Located on the periodic table.
• How do you calculate atomic mass?
• 1. Multiply the mass of each isotope by its
  natural abundance ( common occurrence) in decimal
  form.
• 2. Add all the isotopes products together.

47
Elements Atomic Mass(average mass)

• Carbon (C) has two isotopes
• Carbon-12 has a natural abundance 98.89
• Carbon-13 has a natural abundance 1.11
• Carbons atomic mass
• Isotopes mass number x natural abundance
• C-12
• C-13

48
Elements Atomic Mass

1. Atomic Mass of Au 197.5 amu
2. Atomic Mass of Fe 55.85 amu
3. Atomic Mass of N 14.07 amu
4. Atomic Mass of Si 28.10 amu

49
Kandium Lab

• Purpose To analyze Kandiums isotopes and
  calculate the atomic mass of this new element.

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Chemistry Assignments

• Kandium Lab due-turn in tray.
• Please check infinite campus for missing
  assignments- all make-up work is due by tomorrow
  for partial credit.
• Quiz tomorrow over Atoms (models, subparticles,
  isotopes, and atomic mass calculations)

51
Bell Ringer Atomic Models

• What are the advantages to atomic models in
  science?
• b. What are limitations to atomic models in
  science?

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Atomic Models
Rutherfords Nuclear Model
Daltons Atomic Model
Thomsons Plum Pudding Model
Bohrs Planetary Model
Schrodingers Atomic Model (current model)
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Elements Isotopes and Atomic Mass
Element Isotope Natural Abundance Atomic Mass p n0 e-
Lithium Li-6 7.59
Lithium Li-7 92.41
Lithiums Atomic Mass
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Mass Number vs. Atomic Mass

• What is the difference between mass number and
  atomic mass?
• Complete the table below on Iodines neutral
  isotopes

Iodines Isotopes Natural Abundance () mass number p no e-
I-127 80
I-126 17
I-128 3
3. Calculate the atomic mass of Iodine. Show
work and include units.
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Atomic Structure and Properties

• If most of the atom is empty space, why doesnt
  matter pass through one another?
• What keeps the protons from leaving the nucleus
  and being drawn towards the electrons?

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Atomic Properties

• If most of the atom is empty space, why doesnt
  matter pass through one another?

spiff.rit.edu
57
Atomic Forces

• Electrostatic Forces
• Forces between charged
• particles.
• Nuclear Forces
• Forces that hold the nucleus together.

58
Atomic Forces

• Electrostatic Forces
• Forces between charged
• particles.
• Types of electrostatic forces
• Attractive (p and e-)
• Repulsion (p and p
• e- and e-)
• Nuclear Forces
• Forces that holds p and n0
• together in nucleus.
• Nucear forces gt Electrostatic forces

59
Bell Ringer Atomic Forces

• What are the two primary forces within an atom?
• Distinguish between these forces.
• a. Which one of the forces is stronger ?
• b. Why is this important to the atoms
  existence?

60
Atomic Forces

• Electrostatic Forces
• Forces between charged
• particles.
• Types of electrostatic forces
• Attractive (p and e-)
• Repulsion (p and p
• e- and e-)
• Nuclear Forces
• Forces that holds p and n0
• together in nucleus.
• Nucear forces gt Electrostatic forces