Transcript Periodic Trends in depth

Periodic Trends in depth
• Quiz Friday over periodic trends
• Includes all elements we tested over,
including Uranium and Plutonium
General Trends
• Metals
• To the left of the “stair-step” (Hydrogen is an
exception!)
• Metal Properties
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Shiny
Malleable—can be hammered into sheets
Ductile—can be drawn into wires
Good conductors of heat and electricity
All are solid at room temperature except mercury
General Trends
• Metals
• Metal reactivity:
• Goes up as you move down and to the left on the
periodic table.
• Francium is the most reactive
• Metals tend to form ionic bonds with non-metals
across the periodic table, or
• Metals form metallic bonds with metals
• Positively charged metal ions surrounded by sea of valence
electrons
• Electrons shared and freely flow from ion to ion
General Trends
• Non-metals
• To the right of the stair step
• Poor conductors of heat and electricity
• Brittle solids or gases
• Except for noble gases, tend to form ionic
bonds with metals or covalent bonds with
other non-metals
General Trends
• Non-metals
• Includes Hydrogen, even though it is in group 1
(because it has 1 valence electron)
• Non-metal reactivity
• Goes up as you move up and to the right toward
Fluorine.
• Noble gases do not react
• Diatomic molecules
• Only 7: H2, N2, O2, Fl2, Cl2, Br2, I2
General Trends
• Metalloids
• Properties in-between metal and nonmetal
• Semiconductors: Will conduct electricity
under certain conditions.
• Important in electronics
• On the stair step, except Aluminum,
which is a metal
Element Families
• Group 1: Alkali metals
• Very reactive, not
found alone in nature
• Easily lose one
electron to become
positive ion (cation)
• React violently with
oxygen and water
• Fr most reactive
Element Families
• Group 2: Alkaline earth
metals
• Reactive, but not as much
as group 1
• Not found alone in nature
• Lose two electrons to
become cations (+2
charge)
Transition Metals
• Groups 3-12
• Often colorful
• Some form metallic bonds with other metals
• Some have various oxidation states and bond
with non-metals
Transition metals
• The Iron Triad
• Iron, Cobalt, Nickel (25-28) (across, in
group 4)
• Most common magnetic elements
• Iron is most widely used, 2nd most
common in earth’s crust
Transition metals
• Coinage metals
• Copper, Silver, Gold (29, 47, 79) (down, in group
11)
• Stable and often found as free elements
• Historically used in making coins
• Silver compounds used in photographic film
Transition Metals
• Zinc, Cadmium, Mercury (30, 48, 80) (down, in
group 12)
• Zinc and Cadmium readily combine with oxygen to form
oxides at their surface
• Acts a protective coating.
• Zinc or cadmium often used to coat iron
• Mercury—liquid. Extremely toxic, can collect in body
Inner Transition Metals
• Between groups 3 and 4 in groups 6 and 7
• Lanthanides: follow lanthanum
• Used in movie lighting or in phosphors coating inside
of old tv screens
Inner Transition Metals
• Actinides: follow actinium
• All are unstable, radioactive
• Uranium and Thorium found in earth’s crust
• Uranium used in nuclear reactors and nuclear weapons
• Every element after Plutonium is synthetic (made in
laboratory)
Hydrogen
• Most common element in universe (90 percent)
• Highly reactive with itself (diatomic H2) or other
elements
Group 17: Halogens
• Very reactive
• Fluorine most reactive
• Forms salts with nonmetals (ionic
compounds)
• Iodine essential for
health
Mixed Group Elements
• Groups 13-17
• Contain
combinations of
metals, metalloids,
and/or non-metals
• Groups, families
named after first
element in group