Environmental Chemistry Unit 2

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Environmental Chemistry Unit 2 Materials Structu
re and Uses
http//www.ccsdualsnap.com/miscellan.htm
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Coin Design Competition

• How are coins made?
• http//www.usmint.gov/mint_tours/index.cfm?action
  vtShell

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Link to Previous Learning

• We have learned about physical properties of
  matter
• Physical properties Property of an object that
  can be observed or measured without changing the
  substance
• We have also learned the names and symbols of
  common elements
• In this unit we will learn about chemical
  properties, organization of the elements on the
  periodic table and how it relates to properties
  of the atom

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Properties Make the Difference

• Section 1

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Coin-Design Competition

• In order to apply for the Coin-Design
  Competition, we must decide the composition of
  the coins material
• Need to research the properties of elements that
  could be used to make the coin

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Physical and Chemical Properties of Elements

• Physical Properties
• Property of an object that can be observed or
  measured ______________
• ________________________
• Examples
• Density
• Color
• Melting Point

• Chemical Properties
• ______________________________________________
• Must alter substance to observe
• Indicates how a substance _______with something
  else
• Examples
• Flammability

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Physical and ChemicalChanges

• Physical Changes
• ____________________ of the substance
• Examples
• Crush
• tear
• change in state (solid-liquid-gas)

• Chemical Changes
• ________________________________
• Examples
• food cooks
• iron rusts
• wood burns

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Study Buddy Review

• Classify each as a physical or chemical property
  of matter
• Blue Color
• Ability to Rust
• Density
• Flammability
• Reacts with a base to form water
• Boiling Point
• Reacts with water to form a gas
• Luster
• Mass
• Odor

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The Periodic Table of Elements

• (Section 4)

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Chemical Elements

• Elements Pure substances that __________
• _____________________________________
• Composed of atoms
• Organized by the Periodic Table of Elements

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Dobereiners Triads
THE LAW OF TRIADS The atomic mass of the middle
element of the triad is equal to the
________________________ of the other two
elements.
EXAMPLE Lithium Atomic Mass of 7 Sodium
Atomic Mass of 23 Potassium Atomic Mass of
39
According to Dobereiners Law, the atomic mass of
sodium Should equal the arithmetic mean of
lithium and potassium. (739)/2 23, which is
the mass of sodium.
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Problems with Dobereiners Law of Triads.

• _______________________________________
• __________________________________________________
  _____

2) The law did not work for very low or very
high massed elements such as F, Cl, and Br.
3) As techniques improved for measuring
atomic masses accurately, the law became obsolete.
Dobereiners research made chemists look at
groups of elements with similar chemical and
physical properties.
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Newlands Law of Octaves
When placed in increasing order of their
atomic masses, every __________________________ an
d _________________________.
Li Be B C N O F Na Mg Al Si P S Cl K Ca
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Problems with Newlands Law of Octaves
1) It was not valid for elements that had
atomic masses higher than Ca.
2) When more elements were discovered (Noble
gases) they could not be accommodated in
his table.
However, the modern periodic table does draw from
the concept of periods of eight.
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Mendeleev and Meyer

• Published nearly identical schemes for
  classifying elements
• Arranged elements by ______________________
• Mendeleev generally given more credit
• Published first
• More successful at demonstrating value of table
• Predicted discovery of new elements, properties
  of new elements

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Mendeleevs Table the first periodic table of
the elements. He arranged the table so that
elements in the ____________ _____________________
_________________.
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Problems with Mendeleevs Table
1) The positions of isotopes could not
be accommodated within the table.
2) In order to make the elements fit the
requirements, Mendeleev was forced to put an
element of slightly higher atomic weight ahead of
one of slightly lower atomic weight.
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Henry Moseley (1887-1915)

• Developed concept of ________________
• amount of positive charge in the nucleus
• Later determined that arranging periodic table
  according to increasing atomic number eliminated
  problems seen in Mendeleevs table

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Why is it the periodic table?

• Periodic Law when elements are arranged in order
  of __________
• _________________, their physical and chemical
  properties show a periodic pattern

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Study Buddy Review

• Describe the contribution each person below made
  to the development of the periodic table
• Johan Dobereiner
• John Newland
• Dmitri Mendeleev
• Julius Meyer
• Henry Moseley

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Parts of the Periodic Table
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Parts of Periodic Table

• Groups/families vertical columns
• Alkali metals
• Alkali earth metals
• Boron, carbon, nitrogen, oxygen families
• Halogens
• Noble gasses

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• Horizontal rows are called ___________
• There are 7 periods

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• The elements in the A groups are called the
  representative elements

8A0
1A
2A
3A
4A
5A
6A
7A
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Parts of Periodic Table

• Metals __________ of staircase
• Nonmetals __________ of staircase
• Metalloids elements adjacent to staircase
  (except Al, Po)

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• The group B are called the transition metals

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Study Buddy Review

• Identify the follow parts of the periodic table
• Halogens
• family
• Alkali metals
• Metals
• Inner transition metals
• Noble gases
• Metalloids
• Period

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The Atom
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Early Models of the Atom

• Atom
• Smallest particle of an element that
  __________________________________________________
  __________

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Democritus Kanada

• Democritis
• Greek Philosopher
• 450 BC
• Logic
• ___________________________

• Kanada
• Ancient Indian philosopher
• 4 elements
• air
• fire
• earth
• water
• Made up of tiny particles

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Contributing Principles to Idea of Atom

• ____________________________________
• Antoine and Marie Lavoisier
• Conducted controlled experiments and made many
  quantitative measurements
• Late 1700s

http//images.search.yahoo.com/search/images/
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Contributing Principles to Idea of Atom

• Law of Definite Composition
• A given compound always __________________________
  ____________________________ by mass
• Joseph Louis Proust
• 1799

http//images.search.yahoo.com/search/images/
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John Daltons Atomic Theory (1803)

• Elements composed of small particles called
  _________
• All atoms of a given element are the same, but
  different from other elements
• Atoms ______________
• __________________in a chemical reaction
• Compounds are composed of atoms combined in
  simple whole number ratios

www.english.upenn.edu/jlynch/Frank/People/dalton.
html - 2k
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Study Buddy Review

• Describe the contribution of each towards the
  historical development of the atom
• Lavoisier
• Proust
• Democritus
• Dalton

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What is inside the atom?
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J.J. Thomson (1897)

• Cathode Ray Tube Experiments
• Conclusions
• Stream of negative particles that have mass
• Named________________
• Atoms are not indivisible
• Found ratio
• (electrical charge of electron)
• (mass of electron)
• 1.76 x 108 coulombs 1 gram of electrons

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Robert Millikan (1909)

• Oil Drop Experiment
• Measured ______________________________
• Charge of one electron
• -1.6x10-19C
• THUS.
• Mass of e-
• 9.11x10-28g

http//webphysics.davidson.edu/Alumni/ToHaynie/Oil
Drop/oilappa.htm
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Rutherfords experiment

• English physicist Ernest Rutherford (1911)
• _________________________which can be made a few
  atoms thick.
• alpha particles positively charged helium nuclei
• A form of radioactivity
• When an alpha particle hits a fluorescent screen,
  it glows.

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How Rutherford explained results

• Atom is ____________
• ____________________
• Small dense, positive piece at center. (NUCLEUS)
• Alpha particles are deflected by it if they get
  close enough.

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Credit for Subatomic Particles

• 1897 Thomson discovered the electron
• Used cathode ray tube
• (1918) Rutherford named positive charged particle
  the proton
• Goldstein (1886) first discovered positively
  charged particle using Cathode-ray tube with
  perforated cathode
• (1932) James Chadwick
• Discovered neutrons
• Produced neutrons and their masses
• Worked with cloud chambers

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Subatomic Particles in Atom
Charge Real mass Relative mass
p 1.67 x 10 -24 g 1 amu
e- 9.11 x 10 -28 g 1/1840 amu
no 1.67 x 10 -24 g 1 amu
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Study Buddy Review

• Name three subatomic particles.
• Who is credited with discovering each particle?
• Describe the Rutherford Gold Foil Experiment.

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Information from Periodic Table
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Atomic Number and Atomic Mass

• Chemical Symbol abbreviation for element name
• Atomic Number ____________in nucleus of atom
  (and electrons if neutral)
• Mass Number __________________in nucleus (whole
  number)

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Isotopes

• Isotopes atoms with the same of protons
  _____________________________
• Shorthand notation
• O168 O178
• Average Atomic Mass weighted avg. mass of atoms
  found in nature

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Models of the Atom
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Dalton Model of Atom

• Small, indivisible spheres

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J.J. Thompsons Model of Atom

• Plum Pudding Model, 1896
• Thought an atom was like plum pudding
• Dough was positively charged
• Raisins scattered throughout the dough were
  negatively charged
• Didnt know about neutrons at this time

http//images.search.yahoo.com/search/images/
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Rutherfords Model of the Atom

• Rutherford Model, 1911
• Thought atom was mostly empty space
• Nucleus in center is dense, positively charge
• Electrons (negatively charged) are in empty space
  surrounding nucleus

http//images.search.yahoo.com/search/images/
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Bohrs Model of the Atom

• Neils Bohr, 1913
• Similar to Rutherfords model
• Thought atom was mostly empty space
• Nucleus in center is dense, positively charge
• Electrons move in orbits around the nucleus

http//images.search.yahoo.com/search/images/
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(Modern) Quantum Mechanical Model of the Atom

• Heisenberg, Schrodinger, many others, 1926
• Think atom is mostly empty space
• Nucleus in center is dense, positively charge
• Electrons are around the nucleus
• Cannot locate location of electron at specific
  time

http//particleadventure.org/particleadventure/fra
meless/modern_atom.html