1. Mr. Matthew Totaro Legacy High School Honors Chemistry
Periodic Families and Mendeleev
Mr. Matthew Totaro
Legacy High School
Honors Chemistry

2. Dmitri Mendeleev Ordered elements by atomic mass.
Saw a repeating pattern of properties.
Periodic law —When the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically.
Used pattern to predict properties of undiscovered elements.
Where atomic mass order did not fit other properties, he reordered by other properties.
Te & I

3. Mendeleev’s Periodic Table

4. Mendeleev's Predictions

5. Periodicity Periodic = repeating
When one looks at the properties of elements, one notices a repeating pattern of characteristics & reactivities.
Periodic = repeating

6. Periodicity
= Metal
= Metalloid
= Nonmetal

7. Metals Solids at room temperature, except Hg.
Reflective surface = Luster.
Shiny
Conduct heat.
Conduct electricity.
Malleable.
Can be shaped.
Ductile.
Drawn or pulled into wires.
About 75% of the elements are metals.
Lower left on the table.

8. Nonmetals Found in all 3 states. Poor conductors of heat.
Poor conductors of electricity.
Solids are brittle.
Upper right on the table.
Except H.

9. Properties of Silicon:
Metalloids
Show some properties of metals and some of nonmetals.
Also known as semiconductors.
Properties of Silicon:
Shiny
Conducts electricity
Does not conduct heat well
Brittle

10. The Modern Periodic Table
Determined the atomic numbers of elements from their X-ray spectra (1914)
Arranged elements by increasing atomic number
Killed in WW I at age 28
(Battle of Gallipoli in Turkey)
H.G.J. Moseley ( ) while doing post-doctoral work (with Ernest Rutherford) bombarded X-rays at atoms in increasing number and noted that the nuclear charge increased by 1 for each element. This gave him the idea to organize the elements by increasing atomic number.
Periodic law – elements organized by increasing atomic number on periodic table (1913)
In 1913, Moseley analyzed the frequencies of X -rays emitted by the elements and discovered that the underlying foundation of the order of the elements was atomic number, not atomic mass.
Moseley hypothesized that the placement of each element in his series corresponded to its atomic number Z, which is the number of positive charges (protons) in its nucleus.
Moseley- wavelengths in X-rays determined by the number of protons in the nucleus of the anode atoms
- change anode, change wavelength
Henry Moseley

11. The Modern Periodic Table
Elements are arranged from left to right in order of increasing atomic number
There are 18 vertical columns called Families
There are 7 horizontal rows called Periods.

12. Long Form of the Periodic Table

13. The Modern Periodic Table
Main group = representative elements = “A” groups
Transition elements = “B” groups
all metals
Bottom rows = inner transition elements = rare earth elements
metals
really belong in Period 6 & 7

14. find table that includes rare earth elements

15. Families of the Periodic Table

16. = Alkali metals = Alkali earth metals = Noble gases = Halogens
= Lanthanides
= Actinides
= Transition metals
add pictures of elements from text
Tro: Chemistry: A Molecular Approach, 2/e

17. Important Groups - Hydrogen
Nonmetal
Colorless, diatomic gas
very low melting point and density
Excited Hydrogen Gas

18. Important Groups – Alkali Metals
Group IA = Alkali Metals
Hydrogen usually placed here, though it doesn’t really belong
Soft, low melting points, low density
Flame tests ® Li = red, Na = yellow, K = violet
Very reactive, never find uncombined in nature
lithium
sodium
potassium
rubidium
cesium

19. Important Groups - Alkali Earth Metals
magnesium
calcium
beryllium
strontium
barium
Group IIA = Alkali Earth Metals
harder, higher melting, and denser than alkali metals
Mg alloys used as structural materials
flame tests = Ca = red, Sr = red, Ba = yellow-green
reactive, but less than corresponding alkali metal

20. Important Groups – Halogens
Group VIIA = halogens
Nonmetals
Only family with solids, liquids, and gases
All diatomic
Very reactive
fluorine
chlorine
bromine
iodine
astatine

21. Important Groups - Noble Gases
helium
neon
argon
krypton
xenon
Group VIIIA = Noble Gases
all gases at room temperature
very low melting and boiling points
very unreactive, practically inert
very hard to remove electron from or give an electron to

22. States of the Elements (at STP)
Orange = Solid Red = Liquid Purple = Gas