Unit 2: Atoms and Bonding
2.76 Periodic Table Trends:
6. Families
Textbook ch 7.7 -7.8
Big Idea 1: The chemical elements are fundamental building materials
of matter, and all matter can be understood in terms of
arrangements of atoms. These atoms retain their identity in chemical
reactions. Students will be able to demonstrate understanding by
laboratory investigation, analysis of data and creation of models.
Learning Objectives
SWBAT:
:
• Correlate the atomic properties of elements
based on family with their chemical reactivity
and physical properties
Alkali Metals
 Group 1A elements
 Alkali metals are NEVER found pure in
nature; they are too reactive (ALL react
with water even moisture in the air)
 Metal +H2O
metal hydroxide + H2(g)
 The reaction above very exothermic and Potassium, K
can produce fire or explosion.
reacts with
 Reactivity of these elements increases
water and
down the group
must be
 Silvery appearance, soft enough to cut
stored in
with knife
kerosene
st
 Also have low 1 ionization energies.
 Most reactive metal on periodic table is
in this group- Cs- cesium
 Fr- most unstable of the naturally
occurring elements , highly radioactive
Alkaline Earth Metals
• Alkaline earth metals are less reactive than alkali metals
• Alkaline earth metals are not found pure in nature; they are
too reactive
• 1st and 2nd ionization energies low
• Harder, denser , and melt at higher temp than alkali metals
– Be does not react with water or steam
– Mg reacts slightly with water and more readily with
steam
– Ca and below follow this pattern: Ca +H2O
Ca(OH)2 + H2(g)
Uses:
– Mg = sea water, light weight alloys for
planes and trucks
– Be = dark green form is Emerald. Light
blue/green from is Aquamarine.
– Sr = fireworks and flares
Transition
Metals
Copper, Cu, is a relatively
soft metal, and a very good
electrical conductor.
Mercury, Hg, is the only
metal that exists as a
liquid at room temperature
Lanthanide & Actinide Series
also called inner transition metals
• F-block elements
• Actinides:
– ALL are unstable and
radioactive
• Lanthanides:
– shiny- reactive metals
– readily available
thanks to technology
Poor Metals
• Al,Ga,In,Sn,Tl,Pb,Bi,Po are poor metals.
• They are not very reactive and weakly posses properties
• FYI: Note there is some debate about Po…some resources say
it’s a semimetal …American Chemical Society calls it a poor
metal (acs.org) . I won’t test you on this one.
Properties of Metalloids
or Semimetals
 They have properties of
both metals and nonmetals.
Metalloids are more brittle
than metals, less brittle than
most nonmetallic solids
 Metalloids are
semiconductors of electricity
 Some metalloids possess
metallic luster
Silicon, Si – A Metalloid
 Silicon has metallic luster
 Silicon is brittle like a
nonmetal
 Silicon is a semiconductor
of electricity
Other metalloids include:





Boron, B
Germanium, Ge
Arsenic, As
Antimony, Sb
Tellurium, Te
Nonmetals
• Nonmetals is a family on the periodic table that
includes the nonmetals that didn’t already fit in a
different family. (halogens or noble gas)
• Not to be confused when comparing all nonmetals
to all metals by general characteristics (last PPT)
Nonmetals
H
1
1.00797
 Nonmetals are poor
Hydrogen
conductors of heat and
electricity
 Nonmetals tend to be
brittle
 Many nonmetals are
gases at room temperature
Carbon, the graphite in “pencil
lead” is a great example of a
nonmetallic element.
Examples of Nonmetals
Sulfur, S, was
once known as
“brimstone”
Graphite is not the only
pure form of carbon, C.
Diamond is also carbon;
the color comes from
impurities caught within
the crystal structure
Microspheres
of phosphorus,
P, a reactive
nonmetal
Halogens
(a specific type of non metal
Halogens are never found pure in
nature; they are too reactive
 Halogens in their pure form are
diatomic molecules (F2, Cl2, Br2,
and I2)
Note some debate about At…some resources place it as a
metal… unstable and only micrograms have been produced so
extensive testing impossible!- I won’t test you on this one.
Chlorine is a yellow-green
poisonous gas
Noble Gases
(a specific type of nonmetal)
Noble gases are ONLY found pure in
nature – they are chemically unreactive
(mostly…see next slide)
Colorless, odorless and unreactive;
they were among the last of the natural
elements to be discovered
Neon lights
Neon gas +
electricity
Noble Gases have been forced to
react in lab
• In 1962 1st noble gas compound
synthesized by Neil Bartlett
Today:
• Xe forms three compounds:
– XeF2
– XeF4 (at right)
– XeF6
• Kr forms only one stable
compound:
– KrF2
• The unstable HArF was
synthesized in 2000.
XeF4 crystals
References
www.sciencegeek.net/Chemistry
I modified the original PPTs to fit our needs in AP Chemistry.
Our textbook: Brown, Lemay et all. AP
edition chemistry, 13th edition, 2015