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, all of the elements in group 2
have 2 valence and so on)

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 (rounded)
minus the protons
• Protons do not change in a atom,
neutrons can change, electrons can be
shared or transferred (when bonds are
made)