Transcript C8 Powerpoint Notes

Chapter 8 Periodic Table of
Properties
Review: Mendeleev’s Periodic Table
Periodic Law
• Recall from C7…Elements in the same group
(vertical column) have the same number of
valence electrons resulting in similar
properties
• This idea can be used to predict physical
properties of elements and called Periodic
Trends!
Periodic Trends: Atomic Radius (size)
Trend in Atomic Radius Explained:
• Why does atomic radius decrease across a
period?
– Higher # = more protons = higher core charge
• Increased attraction between p+ & e– e- pulled closer to nucleus = ????
• Why does atomic radius increase down a group?
– Valence electron shell  higher n = higher probability
of finding e- further from nucleus = ????
– Shielding by core e- = less pull on valence e- = ????
Periodic Trends in Ionic (-) Radius
Periodic Trends in Ionic (+) Radius
Trend in Ion Size Explained:
• Cation (+) radii are smaller than atomic radii
– Why?
• Lose of valence e• Results in lower n, resulting in stronger nuclear pull
• Anion (-) radii are larger than atomic radii
– Why?
• Gain of e• Results in increased repulsion between e-
Can you explain the following?
Properties of Metals
¾ of all known elements
• Solid at room temp (NOT Mercury)
• Low IE = give up electrons
• Metallic bonds
– Delocalization
• Malleable, ductile
Alkali Metals
• Alkali Metals Video
• React with not only water, but many other
substances
– Do not find in elemental state
• Sodium and potassium
– Relatively abundant
– nerve impulses
• Your body would not function correctly w/out these
• Ion imbalance effects
Alkaline earth metals
• Alkali and Alkaline Earth Metals Video
• Denser, harder, higher melting & boiling
• Less reactive
– Still not found in elemental form
• Magnesium and calcium most abundant
– Magnesium is the most important
• Alloys
– Calcium most commonly CaCO3
• Seashells, limestone
– Hard Water
Aluminum
• Earth’s crust
• Commercial production
• Aluminum Video
Transition Elements
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Reactivity
In nature
Hardness & melting/boiling points
Color
Magnetism
LAB: Colorful Transition Metals
Uses of Transition Metals
• Copper
– Coins – nickel and penny
– *Electrical conductor
– Water transport
• Silver
– Photographic film
• Alloys
– Different properties (chemical and physical) than individual
metals
• Increased strength, hardness
• Lower electrical and thermal conductivity
• Lower melting point
Properties of Alloys (Cont)
Lower electrical
conductivities result
because impurities block
the path of e- in the
electron sea
Impurities (in this case,
C) occupy the spaces
between atoms
This makes the alloy
stronger because atoms
cannot slide past each
other
Fe
C
Lower melting points
result due to imperfect
crystalline structure
Metalloids
• Properties of both metals and nonmetals
– Nonmetallic structure and chemical behavior
– Luster
– Conduct electricity
• Not as well as metals = semiconductors
• Silicon
– Metallic luster, but diamond structure
– Most common metalloid
– Quartz
Metalloids as Semiconductors
• Remember: Silicon is poor conductor
– Certain impurities increase conductivity
• As small as 1 : 1,000,000!!
• Called doped crystals
– Impurities affect silicon in two ways
• N-type
• P-type
– Junctions: n-type next to p-type
Nonmetals - Carbon
• Distribution
• Allotropes
Nonmetals – Nitrogen Family
• Natural occurrence
• Reactivity
• Nitrogen cycle
2 NO3− + 10 e− + 12 H+ → N2 + 6 H2O
N2 + 8H+ + 8e- + 16 ATP  2NH3 + H2 + 16ADP + 16 Pi
Nitrogen Family (cont)
• Phosphorus
– White phosphorus
• Reactivity
• Physical properties
• toxicity
– Red phosphorus
• Physical properties
Nonmetals – Oxygen Family
• Oxygen
– Abundance
– Reactivity
– Cellular respiration
– O3 allotrope
• Sulfur
– Abundance
– Industrial
Mixed
fertilizers, 54%
Pigments,
fibers and
film, 3%
Petroleum
(aviation,
gasoline,
lubricants), 2%
other industrial
(explsoives,
synthetic
rubber), 6% iron and steel
(cars,
appliances), 1%
Chemicals
(detergents,
food additives,
catalysts,
antifreeze), 17%
Titanium and
pigments
(paints,
linoleum,
paper), 5%
Nonmetals – Halogens and Noble
Gases
• Diatomic
• Reactivity
– Halogens Video
Nonmetals - Noble Gases
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Helium
Neon
Argon
Krypton
Xenon
Radon