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Do Now
The Periodic Table
• Define an element.
• What relationship exists between atomic number, protons and electrons?
Mendeleev’s Periodic Table
Dmitri Mendeleev
History of the Periodic Table
• In 1869, Dmitri Mendeleev, a Russian chemist, used Newland’s observations and other observations to produce the first PERIODIC Table.
• He placed each element on a card with the element’s atomic mass, chemical and physical properties. He arranged the elements in many different ways according to various properties and looked for trends.
• When he arranged the elements according to increasing atomic mass, he noticed that certain similarities occurred at regular intervals. This was considered a “periodic pattern”.
• He arranged all the elements in a table according to increasing atomic mass, starting a new row every time the pattern repeated, and the elements with similar properties fell in the same vertical columns (with a few exceptions). • He had some blank spaces in his table where he thought new elements would be discovered. These blank spaces were used to predict the existence and discovery of new elements.
History of the Periodic Table
• By 1860 more than 60 elements had been discovered.
• Chemists learned about the new elements by reacting them with other elements to form new compounds.
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• In 1865, John Newlands, an English chemist, arranged the known elements according to their properties in order of increasing atomic mass.
• The properties of elements seemed to repeat every eight elements. This pattern is known as the law of octaves. History of the Periodic Table
• By 1886 three new elements were discovered that followed Mendeleev’s predication.
• Most chemists were persuaded to accept his h i
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table, labeling Mendeleev the founder of the periodic law.
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History of the Periodic Table
Modern Russian Table
• In order to keep the pattern of properties, Mendeleev had to switch some elements out of order based on atomic mass.
• In 1911, Henry Mosely, an English chemist, was examining the spectra of 38 different metals. He noticed that the wavelengths of spectra lines correlated to atomic numbers
wavelengths of spectra lines correlated to atomic numbers, not atomic mass.
• Moseley discovered a new pattern and organized the elements according to their increasing nuclear charge, or atomic number, i.e. increasing number of protons.
• When the elements were arranged by increasing atomic number, the discrepancies in Mendeleev’s table disappeared. Chinese Periodic Table
Stowe Periodic Table
A Spiral Periodic Table
Triangular Periodic Table
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“Mayan” Periodic Table
Meet the Elements Music Video
• http://www.youtube.com/watch?v=d0zION8xj
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http://www.youtube.com/watch?v=v1TfPDlA1
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Do Now
• What do you think of when you hear the word metal?
• What is a nonmetal?
• Do you know of any examples of each?
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Properties of Metals
• Metals are good conductors of heat and electricity
• Metals are malleable (can be hammered or rolled into sheets)
• Metals are ductile (can be made into wire)
• Metals have high tensile strength
• Metals have luster
The Periodic Table consists of:
• METALS
• NONMETALS
• METALLOIDS
Examples of Metals
Potassium, K reacts with water and must be stored in mineral oil
Copper, Cu, is a relatively soft metal, and a very good electrical conductor.
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Examples of Metals
Zinc, Zn, is more stable than potassium
Mercury, Hg, is the only metal that exists as a liquid at room temperature
Mixing metals
• Alloy = mixture of a metal with another element, usually another metal
• Alloys have properties different from the individual elements usually eliminating some
individual elements, usually eliminating some disadvantages.
– Alloys are usually harder and more resistant to corrosion
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Properties of Nonmetals
• Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element. Ex: brass = copper + zinc
Ex: sterling sliver = copper + silver
Ex: steel = iron + carbon + manganese + nickel
Ex: Stainless steel = iron + chromium
Examples of Nonmetals
Sulfur, S, was once known as “brimstone”
Microspheres of phosphorus, P, a reactive nonmetal • Nonmetals are poor conductors of heat and l
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electricity
• Nonmetals tend to be brittle
• Many nonmetals are gases at room temperature
Examples of Nonmetals
Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure
Bromine is a nonmetal that exists as a liquid at room temperature.
Properties of Metalloids
• Metalloids straddle the border between metals and nonmetals on the periodic table. • They have properties of both metals and nonmetals.
nonmetals
• Metalloids are more brittle than metals, less brittle than most nonmetallic solids
• Metalloids are semiconductors of electricity
• Some metalloids possess metallic luster
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Silicon, Si – A Metalloid
Silicon has metallic luster
Silicon is brittle like a nonmetal
Silicon is a semiconductor of electricity
Elements classified as metals and nonmetals
Other metalloids include:
Boron, B
Germanium, Ge
Arsenic, As
Antimony Sb
Antimony, Sb
Tellurium, Te
http://www.ptable.com/
Do Now
• Take out your Reference Table and open to the Periodic Table of Elements
• Do you notice any patterns as you look at the properties of elements?
properties of elements?
– Hints: scan left to right, and scan from the top down
The Periodic Table
• PERIODIC LAW
Periodic Table with Group Names
PERIODS= Horizontal rows GROUPS= vertical columns
– The physical and chemical properties of the elements are periodic functions of their atomic numbers (elements with similar properties appear (
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at regular intervals).
• THE MODERN PERIODIC TABLE
– An arrangement of the elements in order of increasing atomic number so that the elements with similar properties fall in the same column or group.
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VALENCE ELECTRONS
• Elements within the same group have the same number of valence electrons. GROUP 1
Alkali Metals VALENCE ELECTRONS
• Most loosely bound electron is called the VALENCE ELECTRON!
• Valence electrons participate in chemical reactions, so elements with similar valence electrons react in similar ways.
• Noble gases are stable with ___ valence electrons.
• All elements with the exception of Hydrogen and Helium want 8 valence electrons to be stable.
• Hydrogen and Helium want __ valence electrons to be stable.
EXCEPTION:
Hydrogen is in group 1,
but has different properties than the alkali metals
• Properties:
–
–
–
–
–
–
–
–
Metal
Easily lose valence electron 1 valence electron
Chemically reactive – do not occur as free elements in nature
Soft, silvery Good conductor of electricity
React violently with water
React with halogens to form salts Hydrogen
• Most common element in the universe.
• It consists of one proton and one electron.
• It can react with many other elements:
– With oxygen to make water
– With carbon to make organic compounds
– With nitrogen to make ammonia
GROUP 2
Alkaline Earth Metals
• Properties:
– They are metals, but have less metallic characteristics than Alkali Metals
Alkali Metals
– 2 valence electrons
– Chemically reactive – do not occur as free elements in nature
– Harder, denser, stronger, higher boiling points, and slightly less reactive than alkali metals
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GROUP 17
Halogens (“Salt makers”)
• Properties:
GROUP 18
NOBLE GASES (or INERT GASES)
• Properties:
– Full set of valence electrons: most elements have 8 valence electrons, except Helium with 2 valence electrons, but it is still g p
associated with this group because its properties match these elements.
– Extremely stable and occur as monoatomic gases in nature
– Although they do not readily combine with other elements, but compounds of Krypton and Xenon have been prepared.
– Most reactive nonmetals.
– 7 valence electrons – need 1 electron to become stable
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– They vigorously react with metals to form salts.
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F2 ‐ most reactive element
Cl2
Br2
I2
Monoatomic Atoms • All of the ____________ gases are monatomic.
• Monatomic means _____________________.
Transition Metals (d‐Block)
They have “typical metallic properties”
Luster, ductile, malleable, good conductors of heat and electricity
Less reactive than Group 1 and 2
Many are unreactive (for example, palladium, platinum and gold are found as pure elements in nature)
• As ions, the transition elements form colorful solutions.
• These elements begin in Period 4 and include Groups 3‐12. •
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Lanthanides and Actinides (f‐Block)
• Lanthanide Series‐ shiny metals similar in reactivity to Alkaline Earth Metals
• Actinides Series‐
i id S i all radioactive (mostly ll di
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synthetic)
Magic seven
• Diatomic molecules= always exist as 2 of the same atoms bonded to each other
H2
N2
O2
F2
Cl2
Br2
I2
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