Transcript Periodic Table PowerPoint

The Periodic Table of
Elements
Periodic Table

Arranged by Russian chemist Dimitri
Mendeleev (late 1800’s)
 Originally
arranged
by increasing atomic
mass
 Later arranged by
increasing atomic #
(Henry Moseley)
Columns

Known as Groups or Families
A
group or family has similar but
not identical properties
 Example:
Group 1 or Alkali
Metals
Properties – soft, white, shiny
metals, highly reactive
We Are Family!
Periodic Table
Organized
into
Rows =
Periods
Columns =
Groups
or
Families
Special Groups
Group 1 – Alkali Metals
 Group 2 – Alkaline Earth Metals
 Group 17 – Halogens
 Group 18 – Noble Gases

Metals/Non-metals
Notice the
dark
stairstep
line.
Separates
metals
from
nonmetals
Metals/Metalloids/Nonmetals
 Metals
 Metalloids
 Properties
between metals and
nonmetals
 Have a side touching the stairstep
line EXCEPT Al (metal)
 Nonmetals
Rows
 Known
as periods
 Are not alike in properties, but there
is a pattern
The first element in a period is
almost always a reactive solid
The last element is an inert or
inactive gas
Group Practice

Give the group number for each element:
 Calcium
 Tellurium
 Cesium
 Chlorine
 Argon
Rows
 Each
period tells you how many
energy levels each atom has
Each energy level can hold a
certain number of electrons
Energy level 1 - 2 electrons
Energy level 2 - 10 electrons
Energy level 3 - 18 electrons
Practice
Give the element from the periodic table:
 Period 2, Group 14
 Period 4, Group 3
 Period 3, Group 17
 Period 1, Group 8
 Period 4, Group 2
 Period 2, Group 4

Why do we care about how many
electrons an atom has?

The reactivity of an element is due to its
valence electrons
 Valence electrons are the electrons
found in the outer shell of an atom.
Shell or Energy Level
Nucleus
Valence Electrons
Trick to the Dot Diagrams

Some atoms are very easy to figure out how
many electrons are in the valence shell
Group 1 has 1
 Group 2 has 2
 Group 13 has 3
 Group 14 has 4 (are you noticing a pattern yet?)
 Group 15 has 5
 Group 16 has 6
 Group 17 has 7
 Group 18 has 8


Groups 3-12 always have 2 electrons
Dot Diagrams

A diagram to represent electrons in the
outer energy level of an atom

Uses the atomic symbol and dots

Example: Hydrogen
H•
Beryllium
Be:
Carbon
:C:
Dot Diagram How-To
Figure out how many valence electrons
the atom has.
2. Write the symbol for the element.
3. Add dots in pairs on each side of the
symbol (imagine that it is inside a box) to
represent the valence electrons.
Example:
 Silicon
 4 valence electrons
1.
Dot Diagram Practice
Draw Dot Diagrams for each of the
following:
 Hydrogen
 Chlorine
 Calcium
 Nitrogen
 Aluminum
