notes: periodic table -...
TRANSCRIPT
• Periodic Table
– The most important chemistry reference
– Presents all the elements by showing their similarities and differences.
Notes: PERIODIC TABLE
• The periodic table was first created by Russian chemist Dmitri Mendeleev in 1869. He arranged the elements based on similar chemical and physical properties.
• Mendeleev left blank spaces in his tables basically predicting the existence of unknown elements.
Element: a pure substance that can not be separated by chemical or physical means These are the basic things that make up everything in the universe!
Fixed by Moseley
A few elements were not in the right place on Mendeleev’s table and 30 new elements had been
discovered. In 1914 scientist Henry Moseley rearranged the elements by their atomic numbers
and every element fell into its proper place.
Atomic Number: the number of protons in an atom
The Periodic Table
Decoding the Periodic Table
Let’s examine just one square to make this easier…
8
O Oxygen
15.9994
8
O Oxygen
15.9994
Chemical Symbol: the symbol for each element is 1 or 2 letters. The first letter is always capitalized and the second is always lowercase.
Chemical Symbol
8
O Oxygen
15.9994
Chemical Name: The name of the element is sometimes shown along with the symbol
Chemical Name
8
O Oxygen
15.9994
Atomic Number: Represents the number of protons in the atom of the element. The larger the atomic number the larger the atom of that element.
Atomic Number
(This is the number Moseley used to re-organize the periodic table)
8
O Oxygen
15.9994
Atomic Mass: Represents the number of protons plus the number of neutrons in an atom of the element.
Atomic Mass
Across the Periodic Table
Each horizontal row of
elements is called a
PERIOD
Down the Periodic Table
Each vertical row of
elements is called a
GROUP or FAMILY
Classifying the Elements
Elements are arranged on the table by their properties. Based on those properties we can now classify the elements as Metals,
Non-metals, and Metalloids
METALS
Most elements are metals. Metals are
elements that are shiny, ductile,
malleable, and good conductors of
heat and electricity
Malleable – easily shaped
Ductile - flexible
NON-METALS
Non-metals are elements that are dull
and poor conductors of heat and
electricity
METALLOIDS
Metalloids are elements that have
properties of both metals and non-
metals
Periodic Table Pop Quiz
1. Name at two properties of metals.
2. On what side of the periodic table are non-metals located.
3. The second letter in a chemical symbol is always _________________.
4. Who created the first periodic table Mendeleev or Moseley?
5. True or False – Elements in a Period have the same physical and chemical properties.
6. Which direction do Families or Groups go on the periodic table? Across or Down