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 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
(exception: hydrogen)
• Solid at room temp (exception: mercury)
Properties:
– Shiny
– Ductile
– Malleable
– Good conductors
4.
5. 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)
6. 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
7. 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 (weighed average of isotopes)
• Background color (identifies metals,
nonmetals and metalloids on table)
8. • 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
• Rows-determines the number of energy
levels – 7 rows on the table
• Properties gradually change moving left to right
across each row from reactive (group 1) to non-
reactive (group 18)
9. Energy Levels
• 1st
energy level – 2 valence electrons (max)
• 2nd
energy level – 8 valence electrons (max)
• 3rd
energy level – 18 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. • Columns (up and down) 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 last energy level
• 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)
11. Bonds
• To form bonds, elements must reach a full
state of 8 valence electrons in the last
energy level (octet rule)
• (Exception: Helium - would be first energy
level which is full at 2)
12. Group 1: Alkali metals
• Metals
• Valence 1
• Very reactive with H2O, O2 and other
elements
• Makes compounds with halogens (group
17) easily to form salts
14. Group 3 – 12: Transition
• Metals
• Valence 1 or 2 (depending on element)
15. Lanthanides and Actinides
(Rare earth metals)
• 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
16. Group 13: Boron Group
• Has 1 metalloid and 4 metals
• Valence 3
17. Group 14-Carbon group
• 1 nonmetal, 2 metalloids and 2 metal
• Valence 4
• Carbon forms organic compounds (all
living things contain carbon), makes more
compounds than any other element
18. Group 15-Nitrogen Group
• 2 nonmetals, 2 metalloids, 1 metal
• Valence 5
• P is extremely reactive and only appears
in compounds
20. Group 17-Halogens
• Nonmetals
• Valence 7
• has violent reactions with alkali-metals
(group 1) to form salt compounds
– Highly reactive with other elements
– Do not appear in nature alone only in
compounds
21. Group 18-Noble Gases
• Nonmetals
• Valence 8 valence (full level)
• except helium which has 2 valence
electrons, which makes helium full
• very un-reactive – inert
• Do not form compounds
22. Hydrogen
• Nonmetal
• Valence 1 electron in last energy level so
it is set above the alkali metals
• Properties: even though above metal
category, has properties of nonmetals
• Most abundant element in universe,
makes up stars
23. • Protons = Atomic number
• Electrons = protons
• Neutrons = mass number (rounded)
minus the protons
• Protons do not change in a atom,
• neutrons can change (isotopes),
• electrons can be shared or transferred
(when bonds are made)
24. Reflection Questions
• 1. What are the seven horizontal rows of
the table called? How are the elements of
a row related?
• 2. What are the vertical columns of the
table called? How are the elements of
each column related?
3.What basic information is contained in the
table?
