The periodic table organizes elements according to increasing atomic number and displays their chemical and physical properties. Dmitri Mendeleev arranged elements in a table that predicted undiscovered elements. Henry Moseley determined that atomic number, not atomic mass, was key to the table's structure. Elements are classified as metals, nonmetals, and metalloids based on their locations and properties. The table shows how elements' properties periodically repeat according to their atomic structure.

1. Periodic Table
• Dmitri Mendeleev-recognized that
elements had repeating patterns (periodic)
and organized elements into a table by
increasing atomic mass
• With table he was able to predict that
there would be elements still unidentified
by the gaps in his table

2. • Henry Moseley - determined that the
number of protons - atomic number (which
is unique to each element) would allow the
elements to fit into very specific pattern
• All identified elements follow the periodic
law – chemical and physical properties
change periodically with atomic number

3. Metals
• Most elements are metals
• Found to the left of the zigzag line
• Solid at room temp (exception: mercury
and hydrogen – nonmetal)
• Properties:
– Shiny
– Ductile
– Malleable
– Good conductors

4. Metalloids
• Also called semiconductors
• Border the zigzag line (exception Al)
• Have properties of both metals and
nonmetals depending on the conditions
• properties: depending on conditions
– Brittle
– Good conductors
– Some shiny (others dull)

5. nonmetals
• More than half are gases at room temp
• To the right of the zigzag line
• Properties:
• Not malleable or ductile
• Not shiny or dull
• Poor conductors

6. Each square on table
• Each square includes:
• elements name
• chemical symbol (color coded to identify if
element is a solid, liquid or gas at room
temp)
• Atomic number (protons)
• Atomic mass
• Background color (identifies metals,
nonmetals and metalloids on table)

7. • First letter of chemical symbol is always upper
case and any additional letters are lower case
• Newest elements have temporary 3 letter
symbols
• Rows (left to right) are called periods-
determines the number of energy levels
• Properties gradually change moving left to right
across each row from reactive (group 1) to non-
reactive (group 18)

8. • Columns are called groups or family
• Elements in the same group or family have
similar properties moving up and down each
column
• Each element in a family has the same number
of valence electrons in the outer shell
• Group number determine the valence electrons
(ex: group one – all elements in group 1 have 1
valence electron)

9. Energy Levels
• 1st energy level – 2 valence electrons (max)
• 2nd energy level – 8 valence electrons (max)
• 3rd energy level – 8 valence electrons (max)
• And so on….
• Each energy level can have less valence
electrons but they can not have more than
the maximum valence electrons.

10. Bonds
• To form bonds, elements must reach a full
state of 8 valence electrons in the
outermost energy level (octet rule)
(Exception: would be first energy level
which is full at 2-helium)

11. Group 1: Alkali metals
• Metals
• 1 valence electron in outer level (easily
shared and form compounds easily)
• Very reactive with H2O, O2 and other
elements
• Don’t appear in nature by themselves,
only as compounds

12. Group 2 – Alkaline-Earth Metals
• Metals
• 2 valence electrons in outer level (slightly
less reactive)

13. Group 3 – 12: Transition
• Metals
• 1 or 2 valence electrons in outer level
(depending on element) and are less
reactive

14. Lanthanides and Actinides
• In periods 6 and 7 and appear at the
bottom of the periodic table to keep table
from being to wide
• Lanthanides are shiny reactive metals
• Actinides are unstable radioactive
• All elements after Pu-94 (plutonium) are
man-made in labs and don’t occur in
nature

15. Group 13: Boron Group
• Has 1 metalloid and 4 metals
• 3 valence electrons in outer level and are
semi reactive

16. Group 14-Carbon group
• 1 nonmetal, 2 metalloids and 2 metal
• 4 valence electrons in outer level and
most non-reactive depending on element
• Forms organic compounds (all living
things contain carbon)

17. Group 15-Nitrogen Group
• 2 nonmetals, 2 metalloids, 1 metal
• 5 valence electrons in outer level and
reactivity depends on conditions and
element
• P is extremely reactive and only appears
in compounds

18. Group 16-Oxygen Group
• 3 nonmetals, 1 metalloid, and 1 metal
• 6 valence electrons in outer level and
reactivity depends on element
– Po-84 is radioactive

19. Group 17-Halogens
• Nonmetals
• 7 valence electrons in outer level and has
violent reactions with alkali-metals to form
salt compounds
– Highly reactive with other elements
– Do not appear in nature alone only in
compounds

20. Group 18-Noble Gases
• Nonmetals
• 8 valence electrons in outer level (full
level) (except helium which has 2 valence
electrons, which makes helium full) and
very un-reactive – inert
• Do not form compounds under normal
conditions

21. Hydrogen
• Nonmetal
• 1 electron in outer level so it is set above
the alkali metals and is reactive
• Properties: even though above metal
category, has properties of nonmetals
• Most abundant element in universe,
makes up stars

22. • Atomic number = Number of Protons
• Electrons equal to the number of protons
• Neutrons equal atomic mass minus the
protons
• Protons do not change in a atom,
neutrons can change, electrons can be
shared or transferred (when bonds are
made)