Chapter 4-Periodic Table

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Chapter 4-Periodic Table

• Developing the Periodic Table
• A. Johann Dobereiner
• 1. Grouped elements in triads
• 2. Used similar properties
• 3. Middle element mass was
• average of other two

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• B. John Newlands
• 1. arranged in order of atomic mass
• 2. properties repeated every eighth
• element (Law of Octaves)
• 3. had 7 groups
• C. Dmitri Mendeleev-Father of Periodic Table
• 1. arranged in order of atomic mass
• 2. allowed periods to be any length
• so properties were similar in columns
• 3. left blank spaces for undiscovered
• elements predicted their properties

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• D. Henry Moseley
• 1. used x-rays to show of protons
• in nucleus
• 2. The Periodic Law-properties of
• elements are a periodic function
• of their atomic s.
• 3. rearranged elements in order of
• atomic number
• E. William Ramsay
• 1. discovered noble gases/
• added group 18 to periodic table

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• F. Glenn Seaborg
• 1. took Lanthanides Actinides out of
• main body of Periodic Table
• G. Todays Periodic Table
• 1. horizontal rows periods or series
• properties are periodic-change in
• a repeating pattern
• period is outer energy level
• 2. vertical columns groups or families
• similar properties due to same outer
• electron configuration (valence electrons)

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• II. Regions of Elements
• A. Metals-react by losing electrons
• (located left of stair-step line)
• 1. Structure Atoms in linear layers
• causes shiny luster/silver color,
• malleable ductile
• 2. Structure Atoms closely packed
• causes good conductivity,
• solids at room temp, high density, high BP
  MP

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• B. Nonmetals-react by gaining electrons
• (located right of stair-step line)
• 1. Structure Atoms at angles
• causes dull luster, brittle
• 2. Structure Atoms spaced apart
• causes poor conductivity,
• many states at room temp,
• low density, low BP MP

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• C. Metalloids B, Si, Ge, As, Sb, Te
• (located on stair-step line)
• are all semi-conductors
• (conduct better when warmed)
• D. Noble Gases Group 18
• do not react under normal conditions

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• III. Families of Elements
• A. Alkali Metals Group 1
• (does not include H)
• 1. Soft-can be cut with a knife
• 2. react quickly with oxygen
• -get a dull coating
• -must be stored in oil
• 3. react strongly with water to form
• hydrogen gas alkaline (basic)
• solutions
• 4. have 1 valence electron (end in s1)
• react by losing 1 electron

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• B. Alkaline Earth Metals Group 2
• 1. found in minerals rocks in Earths
• crust
• 2. form precipitates (solid in a solution)
• 3. react slowly with oxygen
• -get a dull coating
• 4. react slowly with water to form
• hydrogen gas alkaline solutions
• 5. have 2 valence electron (end in s2)
• react by losing 2 electrons

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• C. Halogens Group 1 7
• 1. React with metals to form salts
• 2. form strong acids
• 3. have 7 valence electrons
• (end in s2p5)
• react by gaining or sharing 1 electron

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• D. Noble Gases Group 18
• 1. not normally reactive
• 2. have 8 valence electrons
• (end in s2p6-except He s2)
• Octet full s p sublevels
• this is most stable arrangement
• of electrons
• other elements gain or lose electrons when they
  react to get an octet

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• E. Hydrogen-considered its own group
• 1. reacts with most other elements
• 2. has only 1 electron
• (electron configuration 1s1)
• 3. can react 3 different ways
• a. lose 1 electron like Group 1
• b. gain 1 electron like Group 17
• c. share 1 electron like Group 17
• 4. all acids contain Hydrogen (H1)

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• F. Transition Metals Groups 3-12
• 1. form colored compounds
• 2. electron configurations end in
• d sublevels
• 3. electrons may jump between
• d s or p clouds to make atom
• more stable
• (full or half-full sublevels)
• so patterns may have exceptions
• can lose different s of electrons

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• G. Inner Transition Elements
• or
• Rare Earth Elements
• electron configurations end in f sublevel
• 1. Lanthanides Elements 57-70
• are super-conductors
• 2. Actinides Elements 89-102
• are radioactive

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• IV. Periodic Properties (Periodicity)
• properties that change in a
• pattern or cycle

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• A. Vertical changes
• 1. Reasons for changes
• -valence electrons farther from nucleus
• -more shielding from inner electrons
• 2. Results-
• a. Ionization Energy lower at bottom
• (energy to lose electrons)
• -metals at bottom more reactive
• b. Electronegativity lower at bottom
• (ability to attract electrons)
• -nonmetals at bottom less reactive

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• B. Horizontal changes
• 1. Reasons for changes
• -bigger nuclear charge (more )
• -different valence electrons
• 2. Results-changes at right
• a. Ionization Energy higher
• metals at right less reactive
• b. Electronegativity higher nonmetals at
  right more reactive

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• 3. Exceptions to patterns
• a. Noble Gases
• -Octet too stable to change
• b. full or half-full sublevels are harder to
  change
• (electrons are going into next sublevel
• or pairing up -takes more energy)
• c. transition metals can rearrange electrons

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• V. Radioactivity
• breakdown of nucleus to release
• particles and/or energy
• A. Quarks
• particles that make up protons neutrons
• - can recombine to produce other particles
• -these leave nucleus at speed of light
• E mc2

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• Nuclear Particle Symbols
• protons
• neutrons
• alpha particles
• beta particles
• positrons
• gamma rays

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• B. Nuclear fission
• element splits apart into 2 or more particles
  
• (decay) or
• is bombarded and form smaller element
• Used in nuclear power plants, radioactive
• dating, medical imaging, cancer treatments
• Example
• Carbon-14 decays to produce
• Nitrogen-14 and one other particle.

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• C. Nuclear fusion
• 2 smaller elements join together or
• element is bombarded to form
• larger element
• Used in sun stars, hydrogen bomb,
• forming synthetic elements
• Example
• Einsteinium-253 is bombarded with
• alpha particles to form Mendelevium-256
• and one other particle.

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• D. Radioactive Half-Life
• time needed for one-half of
• radioactive material to decay
• Can be use to calculate age of
• fossils, rocks, artifacts, etc.

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• 1. Carbon-14 dating
• -compares ratio of C-14/C-12 in
• fossil to similar objects of
• known age
• -can only be used on objects that were once
  living
• -cannot be used on objects more than 50,000 years
  old
• Problem-if carbon amounts have been different in
  past, ages calculated could be incorrect

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• 2. Potassium-40 dating
• -compares amount of K-40 with
• Ar-40 in rocks to calculate
• starting amount of K-40
• Problem-if Ar-40 was in rock
• when it formed, ages calculated
• could be incorrect

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• Half-Life Problems
• 1. Phosphorus-32 has a half-life of 57.2
• years. How many grams remain after
• 286 years if you have 4.0 grams of the
• isotope at the beginning?

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• 2. The half-life of Polonium-218 is
• 3 minutes. If you start with 16 mg of
• Polonium-218, how much time must
• pass until only 1.0 mg are left?