Transcript Periodic Table PPT

ELEMENTS
Remember:
• Atoms of one type form an element
• Elements are the simplest form of a
substance
• Every element is unique and has its own
chemical and physical properties
Dimitri Mendeleev
• Russian chemist who
worked in the mid
1800’s
• Researched the 63
known elements
• Made cards for each
element with all the
facts he could find
• Developed the first
periodic table by
atomic mass
• Not perfect!!
Henry Moseley
• British scientist who
determined atomic
numbers for the
elements
• When elements
arranged by atomic
number and
properties every
element fell in place
perfectly
• Periodic Law: Properties of elements repeat in a
predictable way when atomic numbers are used to
arrange elements into groups.
Elements are arranged:
Vertically into Groups
Horizontally Into Periods
Why?
If you looked at one
atom of every element
in a group you would
see…
Each atom has the same number of
electrons in it’s outermost shell.
• An example…
The group 2 atoms all have 2 electrons
in their outer shells
Be (Beryllium)
Atom
Mg (Magnesium) Atom
• The number of outer or “valence” electrons
in an atom effects the way an atom joins
with other atoms.
• The way atoms join determine many
properties of the element.
• This is why elements within a group
usually have similar properties.
If you looked at an atom from each
element in a period
you would see…
Each atom has the same number of
electron holding shells.
An example…
The period 4 atoms each have 4 electron
containing shells
4th Shell
K (Potassium)
Kr (Krypton)
Atom
Atom
Fe (Iron) Atom
Each group has distinct properties
• The periodic Table is divided into several
groups based on the properties of different
atoms.
Alkali Metals
Soft, silvery colored
metals
Very reactive especially
with water
Not found in pure form
in nature
Alkaline Earth Metals
Silvery-White Metals
Fairly reactive
Many are found in rocks in
the earth’s crust
Transition Metals
Most are good
Conductors of
electricity
Malleable (easily
bent/hammered into
wires or sheets)
How many things can you think
of that have Transition Metals in
them?
Metalloids lie on
either side of the
“stairstep” line
They share properties with
both metals and non-metals
Si (Silicon) and Ge
(Germanium) are very
important “semi-conductors”
Where are semiconductors used?
Nonmetals
Brittle
Do not conduct
electricity
Groups 13-16
Group 13Boron Group
Group 14Carbon Group
Group 15Nitrogen Group
Group 16 Oxygen Group
Halogens
Most are
poisonous
Fairly reactive
Chlorine Gas was used as a
chemical weapon during World
War I.
It was used by the Nazis in World
War II.
Noble Gases
Non-reactive
Gases at room
temperature
Very Stable
WHY STABLE?
Noble gases have full valence levels!
•Share properties of Group 3
transition metals
•Rare and some are radioactive
•Elements with atomic numbers
greater than 92 (Uranium) are
synthetic.
Lanthanide Series
Actinide Series