Transcript ppt 3 Elements & Per Table

Elements
Elements are substances that cannot be broken down into
simpler substances. They are the simplest substances.
Every substance in the universe is a combination of
one or more elements.
Atoms are the smallest units of an element that have
the properties of that element.
•The elements and their symbols are shown on the
PERIODIC TABLE
• How many elements are there?
PERIODIC
TABLE
92 elements
occur
naturally on
Earth; 23
have been
created by
scientists in
laboratories.
listen to the “Element Song”
Elements are arranged on the
Periodic Table:
Vertically into Groups
Horizontally Into Periods
Why?
If you looked at one
atom of every element
in a group you would
see…
 Every atom in a group
has the same number of
electrons in its outermost
level.
For example…
The Group 2 atoms all have 2 electrons
in their outer level
Be (Beryllium)
Atom
Mg (Magnesium) Atom
• The electrons in an atom’s outermost level
are called the valence electrons.
• The number of valence electrons in an
atom affects the way the atom bonds with
other atoms.
• This is why elements in a group have
similar properties– because they have the
same number of valence electrons.
Electron Dot Diagrams show the number of
valence electrons in an atom.
Observe the electron dot diagrams
of the Period 2 elements below.
What do you notice?
Electron Dot
Diagrams
Each group has distinct properties
• The Periodic Table is divided into groups
(vertical columns) based on the properties
of each group’s elements.
Groups whose elements behave very similarly
are called a family.
Alkali Metals (Group 1)
 Soft, silvery-colored
solids
Have 1 valence electron
 Very reactive!!! especially
with Halogens (Group 17)
video showing alkali metals mixing
with water. Stand back…
sodium reacting with water
more Na + H2O
Alkali
Metals
Lithium
Sodium
Potassium
Rubidium
Francium
Cesium
Alkaline Earth Metals
(Group 2)
 Silvery-White Solids
 Have 2 valence electrons
 Fairly reactive
 Many are found in rocks
in the earth’s crust
Beryllium
Magnesium
Calcium
Alkaline Earth Metals
Strontium
Barium
Radium
Transition Metals
Groups 3 to 12
 Most are good
conductors of
electricity
 Malleable
(easily
hammered into
sheets)
 Ductile (easily
• Solids (except for Mercury)
• Shiny luster
extruded into
wire)
• High melting
points
Uses of
Transition
Metals
Metalloids
• share properties
with both metals and
non-metals
QuickTime™ and a
TIFF (Uncompress ed) dec ompres sor
are needed to s ee this pic ture.
• Si (Silicon) and Ge
(Germanium) are very
important semi-conductors.
• Semi-conductors are used in
computer technology.
What are semiconductors used in?
Nonmetals
 Solids are brittle
(break easily, don’t
bend)
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
 Do not conduct
electricity
 Some are gases, some are solids,
one is a liquid.
Non-Metals:
Solids
Halogens (Group 17)
Have 7 valence electrons
Reactive, especially with Alkali
Metals (Group 1)
 Exist as diatomic molecules
(F2, Cl2, Br2, I2), so that both
atoms have a full outer electron
layer.
Cl
Cl
Remember:
BRINCLHOF
Halogens
Uses of the Halogens
• Fluorine is put into water supplies to kill
harmful bacteria and to help keep teeth
healthy.
• Chlorine is used in swimming pools to
kill bacteria in the water.
• Bromine is used in pesticides. Silver
bromide is used in photography.
• Iodine is used as an antiseptic on cuts,
and as an indicator for starch.
Noble Gases
(Group 18)
 Outer electron levels are full
 Non-reactive (stable)
 Gases at room temperature
 Low melting & boiling points
 Exist as single atoms rather
than diatomic molecules
(He, Ne, Ar, Kr, Xe, Rn)
Helium is lighter then air and is
used in balloons and airships.
Jellyfish lamps made with noble
gases artist- Eric Ehlenberger
Colors Noble Gases
produce in lamp tubes:
• Ne (Neon): orange-red
• Hg (Mercury): light blue
• Ar (Argon): purple
• He (Helium): pale peach
• Kr (Krypton): silvery-white
• Xe (Xenon): blue-green
Lanthanide Series
Actinide Series
Lanthanides & Actinides
 Both are silver, silvery-white, or gray metals.
 The metals have a high luster, but tarnish
readily in air.
 The metals have high electrical conductivity.
 Many fluoresce under UV light.
Lanthanides are relatively soft, have high
melting and boiling points, burn in air, and are
very reactive. Most are widely used in lasers.
Actinides are very dense radioactive metals,
which combine directly with most nonmetals.
Really Important Elements
We are all
carbon-based
life forms;
carbon is found
in every living
thing on Earth.
78% of the
Earth’s
atmosphere
is Nitrogen.
Oxygen makes up
21% of Earth’s
atmosphere, 47%
of the Earth’s
crust, and is
found in 100% of
all living things on
Earth.
The 8 most common elements in
Earth’s crust (by mass):
46.6% Oxygen (O)
27.7% Silicon (Si)
8.1% Aluminum (Al)
5.0% Iron (Fe)
3.6% Calcium (Ca)
2.8% Sodium (Na)
2.6% Potassium (K)
2.1% Magnesium
(Mg)
Top 10 elements in the human body
1. Oxygen (65%)
2. Carbon (18%)
3. Hydrogen (10%)
4. Nitrogen (3%)
5. Calcium (1.5%)
6. Phosphorus (1.0%)
7. Potassium (0.35%)
8. Sulfur (0.25%)
9. Sodium (0.15%)
10. Magnesium (0.05%)
Hydrogen
Nitrogen
Some Cool Elements
Bismuth
Mercury
the only metal that is
liquid at STP
Elements used in jewelry
Gold
Silver
Platinum
Mendeleev’s Periodic Table
Dmitri Mendeleev (1834 - 1907) organized the 63
elements that were known at that time (1869)
into the Periodic Table. He predicted the
existence of 3 elements that had not yet been
discovered, based on the gaps in his periodic
table. The 3 elements were discovered later
(scandium, gallium, germanium).
Early versions
of Mendeleev’s
table
Glenn
Seaborg
(1912-1999)
• Discovered 8
new elements
• Only living
person for
whom an
element was
named (Sg,
seaborgium,
element 106)
Other scientists who have had
elements named after them…
Rutherford
Bohr
Meitner
Roentgen
Curie
Einstein
Fermi
Mendeleev