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
4
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
5
What distinguishes each element below from one
another?
6
Distinguishing Atoms
7
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
10
Elements Subatomic Differences
Element Atomic Symbol Atomic Number Mass (amu) of p of n0 of e-



11
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.

15
Common Isotopes of Carbon
C-12
C-13 of p, n0, e-? of p,
n0, e-?
16
Atomic Structure
History, Structure and Properties of the Atom
17
History of the Atom

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

18
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.

19
Aristotle Greek Philosopher (300b.c.)

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

20
John Daltons Atomic Model
21
John Daltons Atomic Model

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

22
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.

23
Thomsons Plum Pudding Model
24
Thomsons Cathode Tube Experiment
l-esperimento-piu-bello-della-fisica.bo.imm.c...
25
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.

26
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.
27
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.
28
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.

29
Rutherfords Model of the Atom
green-planet-solar-energy.com
30
Rutherfords Gold Foil Experiment
31
Rutherfords Conclusion

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

32
Rutherfords Nuclear Atom Model

33
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.

34
Chadwicks Experiments Neutron
nobelprize.org
35
Bohrs Model of the Atom
http//micro.magnet.fsu.edu/
36
Bohrs Model of the Atom
http//micro.magnet.fsu.edu/
37
Current Atomic Model
Erwin Schrodinger
blogs.stsci.edu
38
Current Atomic Model
Erwin Schrodinger
blogs.stsci.edu
science.howstuffworks.com
39
Current Atomic Model
Erwin Schrodinger
blogs.stsci.edu
40
Types of electron paths around nucleus
41
Bell Ringer

• 1. Compare the different views Aristotle and
  Democritus had about what matter was made of.
• 2. Which Greek philosopher was correct ?
• 3. Which later scientist proved his view?

42
Bell Ringer4. a. Identify and explain this
Atomic Model?b. Who concluded this atomic model?
43
Bell Ringer

• 5. Look at the following experiment below.
• What was this experiment called?
• Who developed this experiment?
• Did his experiment prove or disprove the Plum
  Pudding Model?

44
Rutherfords Conclusion

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

45
Rutherfords Atomic Model
46
Rutherfords Nuclear Atom Model

47
Subatomic Particle Neutron

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

48
Modern Atomic Model
49
Properties of Subatomic Particles
Atomic Subparticles Charge mass (g) mass (amu) subparticles contribution to atom
Electron (- charge) 9.11 x 10 -28
Proton ( charge) 1.674 x10-24
Neutron (neutral) 1.675 x10-24
50
Neutral Atoms
51
Subatomic Masses (amu)
Subatomic Particle symbol charge Mass (g) (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
52
Atoms Subatomic Particles

• Problem B A cesium (Cs) atom has a mass of 133
  amu and an atomic number of 55. How many p, e-,
  and n0 are there?
• Problem C An iron atom has an atomic number of
  26 and consists of 30 neutrons.
• How many p and e- are there?
• What is irons mass number (amu)?

53
Atomic Subparticles
54
Isotopes

• Isotopes atoms with different number of
  neutrons in their nucleus.
• Elements can have several isotopes.
• Ex. Carbon C-12 and C-14 (mass )
• Mass changes. (varied neutrons)
• Atomic stays the same ( of protons).

55
Elements Isotopes

• Oxygen has three isotopes. They are O-16,
• O-17, and O-18.
• What is the mass number for each isotope of
  oxygen in amu?
• 2. What is the atomic number for each isotope of
  oxygen?
• 3. What is the number of p, n0, and e- for each
  isotope of Oxygen ?

56
Atomic MassElements average mass

• Atomic mass the weighted average mass of all the
  elements isotopes present within a naturally
  occuring sample of matter.
• Calculate Atomic Mass of an Element
• 1. Multiply the mass of each isotope by its
  natural abundance ( common occurance) in decimal
  form.
• 2. Add all the isotopes products together.

57
Atomic Mass(Elements 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
• (12 x 0.9889) ( 13x0.0111) 12.011 amu
• 
  12 amu (2 sig. figures)

58
(No Transcript)
59
Atomic Mass Unit (amu)

• Scientist needed an easier value to describe an
  atoms mass .
• Use a reference isotope as a standard.
• Carbon-12 was chosen as the reference isotope
  because of its natural abundance and strong
  stability.
• Carbons atomic mass unit 12 amu
• Atomic mass unit (amu) 1/12 the mass of a
  Carbon-12 atom.
• Compare atoms mass with Carbon

60
(No Transcript)
61
Periodic Table

• Atomic The elements are arranged in
  numerical order based on the number of protons
  present within their atom.
• Metal vs. Non-metal vs. Metalloids
• Periods vs. Groups

62
Periodic TableMetals

• Metals are the majority of elements on the
  periodic table.
• They are every thing left of the metalloids.
• Some metals are extremely reactive and some dont
  react easily.
• Transition metals are elements that form a bridge
  between the elements on the left and right sides
  of the periodic table.

63
Periodic Table Non-metals

• Non-metals are elements that are poor conductors
  of heat and electric current.
• Because non metals have low boiling points, many
  non metals are gases at room temperature.
• Fun fact-All the gases in the periodic table are
  non metals

64
Periodic Table Metalloids

• Metalloids are elements with properties that fall
  between those of metals and non-metals.
• Metals are good conductors of electric current
  and non-metals are poor conductors of electric
  current.
• Metalloids ability to conduct electric current
  varies with temperature.
• Examples of metalloids
• Boron, silicon, germanium, arsenic, antimony,
  polonium, and astatine.

65
Periodic TablePeriods (rows)
66
Periodic TableGroups

• Each column in the periodic table
• The elements of the group have similar properties
  Electron configurations
• The electron configuration determines its
  chemical properties
• Properties of elements repeat in a predictable
  way when atomic numbers are used to arrange
  elements into groups
• The pattern of repeating properties is the
  periodic law

67
An Elements Isotopes

• Isotopes atoms with different number of
  neutrons in their nucleus.
• Elements can have several isotopes
• Mass changes. (varied neutrons)
• Atomic stays the same ( of protons)
• Chemical properties of an elements isotopes are
  the same because their of protons and electrons
  are the same.

68
Atomic MassElements average mass

• Atomic mass average mass of all the naturally
  occurring isotopes of an element.
• Multiply the mass number of each isotope by its
  natural abundance (decimal form) and then add all
  the isotopes products together.

69
Atomic Mass(Elements average mass)

• Carbon (C) has two stable isotopes
• Carbon-12 has a natural abundance 98.89
• Carbon-13 has a natural abundance 1.11
• Carbons atomic mass
• (12 x 0.9889) 13x0.0111) 12.011 amu

70
(No Transcript)
71
Bell Ringer 9/9/09

• 1. What is an isotope?
• 2. How many isotopes did Kandium have?
• 3. Did each of Kandiums isotope have the same
  mass?
• 4. What two values did you need to calculate
  Kandiums atomic mass?
• 5. After you calculated Kandiums atomic mass
  what other value did you need to determine its
  atomic composition (p,e-, n0)

72
Elements Atomic Mass

• Elements atomic mass average mass calculated
  from its isotopes.
• Isotopes mass (amu) and relative abundance
• Ex. Calculate Nitrogens atomic mass
• Nitrogen-14 has a natural abundance 99.63
• Nitrogen-15 has a natural abundance 0.37

73
Calculating Kandiums Atomic Mass

• MM
• Reesium-
• Skittlium-
• Ka atomic mass

74
Kandium Lab

• Realistically, we can determine an elements
  isotopes mass(g) by using a mass spectrometer.
• Proton 1.67x10-24 g
• Neutron 1.67x10-24g
• Electron 9.11x10-28g (very insignificant)
• Mass in grams for an atom is important
  information but values are not easy to work with
  .

75
Atomic Mass Unit (amu)

• Compare atoms mass with carbon.
• Ex. If Helium has a mass of 4 amu how does it
  compare with Carbons mass in amu?
• Amu 1/12 C, 4(1/12) 1/3x mass of C
• Ex. If Sulfur has a mass of 32 amu, how does it
  compare with Carbon mass in amu.
• Amu 1/12 C 32/12 2.67x mass of C

76
Atom Composition

• If we know the atomic mass and the atomic number
  we can determine the atoms composition of
  e-
• of p
• of n0

77
Atomic CompositionShorthand

• Shorthand method of atomic composition
• Carbon-12 has an atomic of 6
• Ex. Oxygen-16 has an atomic of 8
• Ex. Silicon-28 has an atomic of 14

78
Periodic Table

• The periodic table is arranged in numerical order
  by an atoms atomic .
• What is an atoms atomic ?
• Why are the elements arranged this way?
• Atoms chemical nature is dependent upon its
  charged particles
• Atoms protons remain conserved with most
  reactions because present within nucleus. The
  of electrons (electron cloud) will fluctuate with
  most reactions

79
Periodic Table Trends

• Organizing atoms based on atomic establishes
  trends
• Period The horizontal rows within a periodic
  table. The atoms in each row share a pattern of
  properties.
• Group The vertical columns of the periodic
  table. Atoms in each group share similar physical
  and chemical properties.

80
Bell Ringer(9/10/09)

• What is the total of atoms making up the
  Kandium sample? Record in table.

• What is the total of atoms making up the
  Kandium sample? Record in table.

• 1. How are elements arranged in the periodic
  table?
• What does period and group refer to on the
  periodic table?
• Identify which subparticles exist in the nucleus
  and the electron cloud.
• Which two subparticles affect the chemical nature
  of atoms?
• What subparticle determines the mass of the atom?
• Which subparticle is also the atomic ?

81
Objectives

• I can determine the atomic composition of atoms
  when I know the atomic mass and atomic .
• I can recognize that the periodic table is
  organized by an elements atomic number.
• I can divide the elements in the periodic table
  into periods and groups.
• I can identify and distinguish between metals,
  nonmetals, and metalloids on the periodic table.
• I can determine if an atom is neutral or has an
  overall charge based on the of electrons
  present within the atom.

82
Periodic Table Trends

• Organizing atoms based on atomic establishes
  trends
• Period The horizontal rows within a periodic
  table. The atoms in each row share a pattern of
  properties.
• Group The vertical columns of the periodic
  table. Atoms in each group share similar physical
  and chemical properties.

83
Periodic Table

• Elements can be classified into 3 groups
• Metals good conductors of electricity and heat.
• Non-metals primary make-up of life.
• Synthetic (man-made) materials.
• Poor conductors of electricity and heat.
• III Metalloids properties of metals and
  non-metals.

84
Neutral Atom

• What are the two charged subatomic particles that
  make-up an atom?
• Neutral atoms protons of electrons
• What happens if they are not balanced?

85
Charged Atom

• Atoms become charged when they gain or loose
  electrons. This would affect the atoms balance
  between of p and of e-.
• Charged atoms are called ions.

86
Ion Types

• Ions charged atoms
• Two types of Ions
• 1. Anion An atom that has gained one or more
  electrons.
• What charge would an anion have?
• Non-metal ions can be anions.
• Ex. What are some examples of anions?

87
Anions

• Ex. Fluorine (F) atomic 9
• Neutral Fluorine F

88
Anion

• Ex. Phosphorous (P) atomic is 15.
• Neutral PhosphorousP

89
Ion Types

• Cations An atom that looses one or more
  electrons.
• What charge would a cation have?
• Metals can be cations.
• What are some examples of cations?

90
Cation

• Ex. Potassium (K) atomic 19
• Neutral Potassium K

91
Cation

• Ex. Iron (Fe) atomic 26
• Neutral Iron Fe

92
Mass vs. Atomic Mass

• Mass of protons and of neutrons in an
  atom.
• Atomic Mass The average mass for an element.
  It is determined by taking in account all the
  isotopes that make-up an element. You must know
  the isotopes relative abundance and mass to
  calculate the atomic mass of the element.
• -Atomic mass observed on the periodic
  table.

93
Atoms To be neutral or charged

• Neutral atom p is equal to e-
• Ions (charged atoms) change in of e-
• a. Cation ( charge) of e- is less
  than in the neutral atom. Ex. Metals (Na )
• of e- subtracting the charge from of
  p
• b. Anion of e- are more than in the
  neutral atom. Ex. Nonmetals. (F-)
• of e- adding the charge to of p

94
Neutral or Not

• Beryllium Be 2
• Sulfur S
• Sulfur S 2-

95

• d) the larger the atom the weaker the strong
  force is --gt larger atoms tend to decay (nuclear
  decay)
• e) also, atoms with certain numbers of protons
  tend to decay--if they have the same number of
  protons and neutrons they tend to be more
  stable--different numbers--more unstable

96

• 5) 4 forces in nature
• a) strong force
• b) weak force
• c) electrical force
• d) gravitational force
• 6) Usages of Nuclear Chemistry
• a) production of power
• b) killing bacteria in food products
• c) medicine -cancer treatments along with
  other usages

97

• 7) Radiation-Radioactivity
• a) radiation is electrically charged particles
  or waves emitted by an energy source or decaying
  atoms.
• b) radioactivity - is radiation from an
  unstable atom that is splitting or undergoing
  decay. There are three types of radioactive
  materials
• Alpha radiation - harmful if inhaled or
  otherwise enter the body - can be stopped by
  clothes, skin or a sheet of paper.

98

• Some producers of alpha particles are among
  the longest lasting waves
• beta particles - more penetrating power than
  alpha but most serious when inhaled or ingested
  -- tend to concentrate in certain body parts,
  such as bone -can cause serious health problems
  with minimal exposure
• gamma radiation-- highest energy levels
  -similar to x-rays, can penetrate the body and
  cause direct damage to internal organs

99
Types of Radiation

• 1. Alpha Radiation an alpha particle emitted
  from radioactive nuclei, consists of 2 protons
  and 2 neutrons, but no electrons
• Not very harmful
• Large atoms are not very stable and need to
  decrease mass
• What is the charge and mass of an alpha particle?
• 2 and 4amu
• Example
• 22688Ra ? 22286Rn 42He
• Radium Radon Alpha Particle

100
Types of Radiation

• Beta Radiation fast moving electron emitted from
  a radioactive element called a Beta Particle.
• Can cause serious health problems especially in
  bones
• Atoms want to have a 1 1 neutron to proton
  ratio
• Beta emission is used to decrease the neutron to
  proton ratio.
• What is the charge and mass on a beta particle?
• -1 and 0
• 146C ? 147N 0-1ß

101
Types of Radiation

• Gamma Radiation Gamma rays are released from
  radioactive nuclei.
• Gamma rays have no mass or charge.
• Gamma rays are very harmful and have a very high
  energy

102

• Effects of radioactive particles on biological
  systems --can alter cellular function
  particularly DNA--carries the cells genetic
  code-causing birth defects-can create mutated
  forms of cells that can cause cancerous growths
• 8) Fusion-Fission
• a) fusion uniting of nuclei of two light
  elements to form heavier nucleus- example sun--

103

• b) fission - a heavy nuclide splits into two or
  more intermediate- sized fragments when hit in a
  particular way by a neutron --utilized by nuclear
  power plants --to make nuclear bombs

104
Periodic Table Trends

• Organizing atoms based on atomic establishes
  trends
• Period The horizontal rows within a periodic
  table. The atoms in each row share a pattern of
  properties.
• Group The vertical columns of the periodic
  table. Atoms in each group share similar physical
  and chemical properties.

105
Elements in a Period (row)

• The mass of an atom increases as you go from left
  to right across any period.

106
Metals, Non-metals, and Metalloids

• Metals shiny, good conductors of electricity
  and heat, malleable, and ductile.
• (primarily solids)
• Non-metals poor conductors of electricity,
  sometimes transparent, neither malleable nor
  ductile, brittle.
• (solids, liquids and gases)
• Metalloids Weak conductors of electricity,
  useful semi-conductors. They can exhibit metal
  and nonmetal properties.

107
(No Transcript)
108
Postulate 4 is actually the Law of Definite
Proportions, by Joseph Louis Proust in 1797.

• a) a given chemical compound always contains the
  same proportion by mass of its constituent
  elements or...
• b) the relative amount of each element in a
  particular compound is always the same,
  regardless of preparation or source.

109

• Assignment Illustrate the following Atomic
  Models
• Daltons Atomic Model
• Thomsons Plum Pudding Model
• Rutherfords Nuclear Model
• Modern Atomic Model.

110
Thomsons Plum Pudding Model