Transcript Mr. Cherry`s Periodic Table Notes

Periodic Table
Chapter 6
Periodic Table

A chart that organizes all known
elements into a grid of horizontal
rows, periods, and vertical columns,
groups, arranged by increasing
atomic number.
Development of Modern Periodic
Table



Mendeleev, First atomic
table, about 63 elements
Organized by atomic mass
Connected atomic mass to
properties of elements
Medeleev
Periodic Law


Henry Moseley, atomic number.
Periodic Law: periodic repetition of
chemical and physical properties of
the elements.
Modern Periodic Table





Increasing atomic number
Horizontal rows called periods
Vertical columns called groups or
families
Main group, representative, elements
Transition Elements
Modern Periodic Table



Metals: left side, good conductors,
solids usually
Metaloids: Stair step, similar
properties of metals and nonmetals
Nonmetals: right side, gases or dull
solids, poor conductors
Alkali Metals





Group 1A – excluding hydrogen
Shiny, malleable, ductile, good
conductors
1 valence electron, readily forms +1
cation
Reacts violently with water
Reactivity increases as you go down
column.
Alkali Earth Metals



Group 2A or 2
Ca, Ba, and Sr react with water
2 valence electrons, therefore form
+2 cations.
Halogens




Highly reactive group
7A or 17
Most are gasses
7 valence electrons, from -1 anion
easily
Noble Gasses



Group 8A or 18
Formally called inert gasses but
actually can react, Xe
Full outer energy level
Periodic Trends






Atomic Radii
Increase down
family
Why?
Decreases down
period
Why?
Higher effective
nuclear charge.
Ionization Energy (IE)






Energy required to remove an electron
from an atom.
How strongly an atom’s nucleus holds onto
its valence electron.
↑ IE, less likely to form positive ions
As you move across period IE increases.
Why?
Increased Charge has stronger hold on
electrons
Ionization Energy (IE)



As you move down group the IE
decreases.
Why?
Electron shielding, further away
Octet Rule



States that all atoms tend to gain,
lose, or share electrons in order to
acquire a full set of eight valence
electrons.
Understanding octet rule helps
determine ions.
Metals form cations, nonmetals form
anions.
Electronegativity





Relative ability of the atoms to attract
electrons in a chemical bond.
Decreases down groups
Increases across period
Francium least electronegative
Fluorine most electronegative