Atoms Molecules Ions

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Atoms - Molecules - Ions
Molecular Basis of Substances
Substances
Compounds
Elements
Molecules
Ion
Atoms
Molecules
Ions
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Periodic Table of the Elements
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Elements
Elements contain one or more of the same type of
atom!
Examples include
Oxygen 8 protons per atom
Copper 29 protons per atom
Gold 79 protons per atom
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Where do the elements come from?
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Why is the Periodic Table important to me?

• The periodic table is the most useful tool to a
  chemist.
• You get to use it on every test.
• It organizes lots of information about all the
  known elements.

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Pre-Periodic Table Chemistry

• was a mess!!!
• No organization of elements.
• Imagine going to a grocery store with no
  organization!!
• Difficult to find information.
• Chemistry didnt make sense.

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• Here are some of the symbols Dalton used for
  atoms of elements and molecules of compounds. He
  probably used a circle for each because, like the
  ancient Greeks, he thought of atoms as tiny,
  round hard spheres.

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Dmitri Mendeleev Father of the Table

• HOW HIS WORKED
• Put elements in rows by increasing atomic weight.
• Put elements in columns by the way they reacted.

• SOME PROBLEMS
• He left blank spaces for what he said were
  undiscovered elements. (Turned out he was
  right!)
• He broke the pattern of increasing atomic weight
  to keep similar reacting elements together.

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• Dmitri Medeleev gave us a functional scheme with
  which to classify elements.
• Mendeleevs scheme was based on chemical
  properties of the elements.
• It was noticed that the chemical properties of
  elements increased in a periodic manner.
• The periodicity of the elements was demonstrated
  by Medeleev when he used the table to predict to
  occurrence and chemical properties of elements
  which had not yet been discovered.

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• Mendeleev left blank spaces in his table when the
  properties of the elements above and below did
  not seem to match. The existence of unknown
  elements was predicted by Mendeleev on the basis
  of the blank spaces. When the unknown elements
  were discovered, it was found that Mendeleev had
  closely predicted the properties of the elements
  as well as their discovery.

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The Current Periodic Table

• Mendeleev wasnt too far off.
• Now the elements are put in rows by increasing
  ATOMIC NUMBER!!
• The horizontal rows are called periods and are
  labeled from 1 to 7.
• The vertical columns are called groups are
  labeled from 1 to 18.

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Periodic Table
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GroupsHeres Where the Periodic Table Gets
Useful!!

• Elements in the same group have similar chemical
  and physical properties!!
• (Mendeleev did that on purpose.)

• Why??
• They have the same number of valence electrons.
• They will form the same kinds of ions.

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Families on the Periodic Table

• Columns are also grouped into families.
• Families may be one column, or several columns
  put together.
• Families have names rather than numbers. (Just
  like your family has a common last name.)

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• The Periodic Law
• Similar physical and chemical properties recur
  periodically when the elements are listed in
  order of increasing atomic number.

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• Introduction
• The periodic table is made up of rows of elements
  and columns.
• An element is identified by its chemical symbol.
• The number above the symbol is the atomic number
• The number below the symbol is the rounded atomic
  weight of the element.
• A row is called a period
• A column is called a group

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• (A) Periods of the periodic table, and (B) groups
  of the periodic table.

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• Periodic Patterns
• The chemical behavior of elements is determined
  by its electron configuration
• Energy levels are quantized so roughly correspond
  to layers of electrons around the nucleus.
• A shell is all the electrons with the same value
  of n.
• n is a row in the periodic table.
• Each period begins with a new outer electron shell

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• Each period ends with a completely filled outer
  shell that has the maximum number of electrons
  for that shell.
• The number identifying the A families identifies
  the number of electrons in the outer shell,
  except helium
• The outer shell electrons are responsible for
  chemical reactions.
• Group A elements are called representative
  elements
• Group B elements are called transition elements.

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• Chemical Families
• IA are called alkali metals because the react
  with water to from an alkaline solution
• Group IIA are called the alkali earth metals
  because they are reactive, but not as reactive as
  Group IA.
• They are also soft metals like Earth.
• Group VIIA are the halogens
• These need only one electron to fill their outer
  shell
• They are very reactive.
• Group VIIIA are the noble gases as they have
  completely filled outer shells
• They are almost non reactive.

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• Four chemical families of the periodic table the
  alkali metals (IA), the alkaline earth metals
  (IIA), halogens (VII), and the noble gases
  (VIIIA).

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Atoms - Molecules - Ions
Metals Nonmetals - Metalloids
Metals A material that has a characteristic
luster or shine and that is a relatively good
conductor of heat and electricity (Metal oxides
react with water to form bases and are located
on the left side of the table)
Nonmetals A element that does not exhibit the
properties of a metal. (Nonmetal oxides react
with water to form acids and are on the right
side of the table)
Metalloids Elements with properties intermediate
between those of metals and nonmetals.
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Periodicity
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Periodic Table 1A
Alkali metals
Very reactive Metals never occur in nature as
pure elements
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Hydrogen

• Hydrogen belongs to a family of its own.
• Hydrogen is a diatomic, reactive gas.
• Hydrogen was involved in the explosion of the
  Hindenberg.
• Hydrogen is promising as an alternative fuel
  source for automobiles

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Alkali Metals

• 1st column on the periodic table (Group 1) not
  including hydrogen.
• Very reactive metals, always combined with
  something else in nature (like in salt).
• Soft enough to cut with a butter knife

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Periodic Table 2A
Alkaline Earth metals
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Alkaline Earth Metals

• Second column on the periodic table. (Group 2)
• Reactive metals that are always combined with
  nonmetals in nature.
• Several of these elements are important mineral
  nutrients (such as Mg and Ca

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Periodic Table 3A
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Boron Family

• Elements in group 13
• Aluminum metal was once rare and expensive, not a
  disposable metal.

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Periodic Table 4A
allotropes of carbon
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Carbon Family

• Elements in group 14
• Contains elements important to life and
  computers.
• Carbon is the basis for an entire branch of
  chemistry.
• Silicon and Germanium are important
  semiconductors.

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Periodic Table 5A
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Nitrogen Family

• Elements in group 15
• Nitrogen makes up over ¾ of the atmosphere.
• Nitrogen and phosphorus are both important in
  living things.
• Most of the worlds nitrogen is not available to
  living things.
• The red stuff on the tip of matches is phosphorus.

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Periodic Table 6A
Chalcogens
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Oxygen Family or Chalcogens

• Elements in group 16
• Oxygen is necessary for respiration.
• Many things that stink, contain sulfur (rotten
  eggs, garlic, skunks,etc.)

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Periodic Table 7A
Halogens
Greek for salt-forming Very reactive
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Halogens

• Elements in group 17
• Very reactive, volatile, diatomic, nonmetals
• Always found combined with other element in
  nature .
• Used as disinfectants and to strengthen teeth.

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Periodic Table 8A
Noble gases
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The Noble Gases
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The Noble Gases

• Elements in group 18
• VERY unreactive, monatomic gases
• Used in lighted neon signs
• Used in blimps to fix the Hindenberg problem.
• Have a full valence shell.

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Periodic Table Transition Metals
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Transition Metals

• Elements in groups 3-12
• Less reactive harder metals
• Includes metals used in jewelry and construction.
• Metals used as metal.

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Periodic Table 2B
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• Names of Elements
• The first 103 elements have internationally
  accepted names, which are derived from
• The compound or substance in which the element
  was discovered
• An unusual or identifying property of the element
• Places, cities, and countries
• Famous scientists
• Greek mythology
• Astronomical objects.

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What is a chemical symbol?

• Chemical symbol tells us what atom it is
• Always a CAPITAL LETTER, sometimes followed by a
  lower case letter
• Ex Oxygen O Nitrogen N Sodium Na
• Cobalt Co Carbon Monoxide CO
• (Co is an element, CO is a compound)

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• Chemical Symbols
• There are about a dozen common elements that have
  s single capitalized letter for their symbol
• The rest, that have permanent names have two
  letters.
• the first is capitalized and the second is lower
  case.
• Some elements have symbols from their Latin
  names.
• Ten of the elements have symbols from their Latin
  or German names.

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Charge (if ion)
Atomic Mass
Symbol
Atomic Number
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Hydrogen
Protons 1 Neutrons 0 Electrons 1
H
1
1
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Sodium
Protons 11 Neutrons 12 Electrons 11
Na
23
11
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Rhenium
Protons 75 Neutrons 111 Electrons 75
Re
186
75
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Rhenium isotope
Protons 75 Neutrons 112 Electrons 75
Re
187
75
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EXAMPLE
How many protons, neutrons and electrons are
found in an atom of
Cs
Atomic number protons and electrons There are
55 protons and 55 electrons
Mass number sum of protons and neutrons 133
55 78 There are 78 neutrons
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Kinds of Atoms

• Ninety-two naturally occurring elements
• Periodic table arranged by grouping atoms based
  on valence electrons (electrons in the outer
  energy levels).
• Octet rule
• Inert atoms have outer level filled.
• Reactive atoms do not have outer level filled.