UNIT 5 – Periodic Laws
THE PERIODIC CHART
• Dalton:
HISTORY
grouped elements by their properties
• Berzelius: gave elements names and symbols
( important because he established order)
Newlands law of the octaves 1st and 8th counted on his
chart were similar
Doberiener developed groups of 3’s called triads, had
math rule mass of 1st plus mass of 3rd divided by 2 =
mass of 2nd
Meyer: graphed elements by masses
• Mendeleyev: University professor in Russia, he
published the Periodic Chart of elements on March 9,
1869 similar to ours. He developed the groups and
series with only 7 major “families”.
• Ramsey: In the 1890’s the 8th family was discovered
• Moseley: grouped chart by the order of
atomic # instead of mass.
• Joliet: produced the 1st synthetic element in 1936, Tc
• IUPAC: A committee that take care of our present chart
( meet every other year in Paris )
Parts
• Families (8) named columns
• Groups (18) numbered columns
• Series / Periods (8) numbered rows
FAMILY NAMES
• ALKALI
- NITROGEN
• ALKALINE
- CHALCOGEN
• “NO NAME”(transition) - HALOGEN
• CARBON
- INERT (NOBLE)
Regions of the Chart
• Active Metals “s” first and second groups of
elements
• Transition “d” groups 3 – 12 metals
• “p” elements of groups 13 – 18
metalloids / nonmetals
metals /
• Rare Earth “f” Rare natural metals and
synthetic elements
•
The Steps
• Metals To the left of the steps (zig-zag)
• Metalloids On / near the steps
• Nonmetals To the right of the steps
Periodic Properties
1. Atom Size
• a) down - family or group increases , add new layers of
electrons ( shells/energy levels)
• b) to right - is smaller, protons have stronger pull
Fr is the largest
F is the smallest
2. Ion Size
• a) Metals who lose electrons are called cations M+
M+ is smaller than M atom
• b) Nonmetals gain electrons are called anions NmNm- is larger than Nm atoms
• 8th family normally does not form ions
3. Activity
• a)Groups/families of metals are down more active
• b) Groups/Families of Nm up is more active
• c) Across ( period/series )
more active-------------- less------------ more active
4 Metallic Properties
• increase as going down
• increase at left
5 Ionization Energy (IE)
• The Energy needed to remove one electron from an element
1st IE
2nd IE
3rd IE
4th IE
Least Energy More E
Somewhat more
Most E
• easy: this depends on the # of valence electrons Metals have a LOW IE
• hard: on inner shells, once valence are gone Nonmetals have HIGH IE
6 Electron Affinity (EA)
• the attraction of an element for its outer shell electron
Metals have a LOW EA / Nonmetals have HIGH EA
7 Electronegativity (EN)
• the energy exchange as a an atom gains one electron
Metals have a LOW EN/ Nonmetals have HIGH EN
Glitch: where a family or group doesn’t fit a pattern, the most common
glitch is 13 group, but groups 2-3, 8, 10 and 15 sometimes break the rules