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Ms. Reynolds

MacArthur High School: (516) 434-7225

Ms. Reynolds


Periodic Table

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Periodic Table
Periodic Table of Elements

Lesson 1

Classifying Elements
  • 1829 Dobereiner’s Triads
  • 1864 Newland's Octaves
  • 1869 Mendeleev – arranged table by Atomic Mass
  • 1913 Moseley: Modern Table – arranged table by Atomic Number
Atomic number represents the number of protons in an atom.

Arrangement of the Periodic Table

Columns (across the top): 
Columns are called groups
Each element in a column will have the same number of valence electrons; similar chemical properties 

Rows (down the side):
Rows are called periods
Each element in a row will have the same number of shells (principle energy levels)

Group Names
1: Alkali Metals: very reactive (1 valence electron)
2: Alkaline Earth Metals(2 valence electrons)
3-11:Transition Metals: ions in colored solutions
17: Halogens: (7 valence electrons)
18:Noble Gases: Complete outer shell -non reactive (Monomers)

Types of Elements
Lesson 2

MetalsFound on the  left side of the PT 
  • malleable (can be hammered into sheets)
  • ductile (can be drawn into wires)
  • shiny (have luster)
  • good conductors of heat and electricity
  • high melting and boiling points
  • DONATE electrons when bonding

NonmetalsFound on the right side of the PT
  • dull (lack luster)
  • brittle (can break easily)
  • poor conductors of heat and electricity
  • low melting and boiling points
  • ACCEPT electrons when bonding

MetalloidsFound on the “staircase” of the periodic table
  • behave as both metals and nonmetals
There are two exceptions:  Al & Po

Atoms vs Ions
Lesson 3

AtomsNeutral particles because #p = #e (as written on PT)
Ionscharged particles because #p do not = #e

Octet Rule: Every element wants a noble gas configuration (complete outer shell). They will lose or gain valence electrons to do so. 

  • have 1 or 2 valence electrons
  • Lose electrons to form POSITIVE ion (ca+ion)
  • lose e- get smaller
  • Radius atomic>ionic

  • have 6 or 7 valence electrons
  • Gain electrons to form NEGATIVE ion (anion)
  • gain e- get bigger
  • Radius atomic<ionic

Cation Example:​ Lithium
​        atom                                       ion

Anion Example:        Fluorine
       atom                                       ion

Determine the number of protons and electrons in each of the following atoms, then identify the ions by including the number of protons and electrons.

Mg atom Mg ion   p+                 p+
        e- e-

Ca atom Ca ion Ca will form a ________

Br atom Br ion Br will form a _________

O atom O ion O will form a ________

K atom K ion         K will form a ________

Electron Dot Diagrams (Lewis Dot)
Lesson 4
  • ​Used to represent the valence electrons of an element. 
  • The symbol is the “Kernel” and represents the nucleus and all non-valence electrons.​

C                                  Br                          Na

Dot Diagrams Atoms vs Ions

Atom                                            Ion





Trends of the Periodic Table
Lesson 5

Atomic Radius
Trends can be found on Table S
Trend from left to right (across a period) =  DECREASES
Trend from top to bottom (down a group) =  INCREASES

Ionic Radius
No table
An atom that has gained or lost electrons will change in atomic size
Metals lose electrons so ionic radius < atomic radius.
Nonmetals gain electrons so ionic radius >atomic radius.

Ionization Energy
The amount of energy required to remove the most loosely held valence electrons from a neutral atom.
Trends can be found on Table S
Trend from left to right (across a period) = INCREASES
Trend from top to bottom (down a group) = DECREASES

Electronegativity (Electron Affinity)
The measure of attraction an atom has for a pair of electrons
Trends can be found on Table S
Trend from left to right (within a period) = INCREASES
Trend from top to bottom (within a group) = DECREASES 

The transfer (gain or lose) of electrons
*think about what elements want to do…

Metals: more active toward the bottom left corner (Fr).
Nonmetals: more active toward the upper right corner (F).
Noble gases have no reactivity - why they weren't discovered for many years (monomers).