Periodic Table Trends Flashcards
Dobereiner
1st- 1800
Groups of 3 elements with similar properties
Newlands
2nd - 1865
Law of octaves- every 8th element repeat
Lothar Meyer
3rd - 1869
Arranged by atomic mass
Chemical properties repeat every so many elements
Dmitri Mendeleev
4th
Atomic mass
Published table and predicted unknown elements left to be discovered (left gaps)
Predicted Ge Ga Sc
Henry Moseley
Arrangement by increasing atomic number
Periodic law
When elements are ordered by atomic # there is a periodic pattern to their chemical and physical properties
Modern periodic table
Groups ⬇️
Periods ➡️
118 elements
Organized by atomic number
Metals
Small number of valence electrons
Easily cation
Good electricity and heat conductors
Stretched into wire
Malleable
Lustrous
Solid at room temp
Nonmetals
Several valence electrons
Easily anion
Poor conductors
Non ductile
Brittle
No luster
Solid liquid or gas at room temp
Metalloid
Similar chem and physical properties of both metals and non metals
B, si, ge, as, sb, te, po
Alkali metals
Group 1A
Soft
Reactive
Stores under oil
Alkali earth metals
Group 2a
Not as soft
React mildly
Only react with water when it is steam
** calmer version of alkali metals**
Halogens
7a
Strong unpleasant odor
Burn flesh
Do not dissolve well in water
React with most metaliods and many nonmetals
Noble gases
8a
Not very reactive
Under normal conditions do not form compounds with other elements
Very stable
Transition metals
B1-10
Contain everyday metals
Metal properties
