Periodic Table Flashcards
Jons Berzelius 1811
Also used the first letter of the element as the chemical symbol, discovered several elements, confirmed law of definite proportions, suggested other chemical symbols as more elements were discovered
John Dalton 1808
First framework for symbols of the known elements (numbered 1-36, oxygen=#1 empty circle, all others had letters/inscriptions inside)
Law of Definite Proportions
Compounds always have the same proportion of the elements that make them up
Dmitri Mendeleev 1869 Periodic Table
Used increasing atomic mass for ordering, elements in the same column had similar properties, gaps were left for predicting new elements that would fit in with the others, first two rows had 7 elements, 3rd and 4th rows had 17 elements, “the properties of the elements were in periodic dependence with atomic mass”
Noble gasses (1890-1900)
Sir William Ramsay isolated helium (had been known through the sun) from terrestrial sources, he was involved in the discovery of Ne, Ar, Kr, and Xe, and added another column to Mendeleev’s table
Periodic Law (1914)
Henry Mosely showed proton variance from one element to another through X-Rays, concluded elements were missing when X-Ray results varied (new arrangement solved most of the gaps). Periodic = is the physical and chemical properties of elements are periodic functions of their atomic number.
Glen Seaborg 1940
Discovered transuranium elements up to 102, positioned the series of lanthanide and actinide, named 106 after himself
Groups 3-12
Transition metals, d block, typical properties
Groups 13-18
Main group elements, p block
Group 17
Halogens: halas=salt, gen=to generate
Group 18
Noble gasses
Lanthanide and Actinide series
F block, lanthanides are similar to alkali earth metals, actinides are radioactive
Most active metal
Francium
Most active non-metal
Fluorine
Atomic radius
Decreases as atomic # increases across a period (electrons are pulled closer as more positive charge is present), and increases going down a group (electrons occupy a higher main energy level)
Ionization Energy
Energy required to remove one electron (and subsequent electrons) from a neutral element of an atom
Main Group Elements (IE)
Increases across a period, decreases down a group
Metals, Metalloids, Nonmetals (IE)
Metals = low, nonmetals = high, noble gasses = unusually high)
Successive Removal of Electrons
Each is harder because there are fewer electrons to shield the attractive forces of the nucleus
Ionization Equation
A + energy –> (A+) + (e-)
Across a period…
Cations become smaller, then anions become smaller
Down a group…
The ionic radii increase similarly to atomic radii
Electronegativity
Measure of an atom’s ability to attract electrons in a chemical compound (usually increases going across a period and decreases/stays the same down a group, especially for transition metals)
Most electronegative?
Fluorine
Most electropositive?
Francium
Electron Affinity
Energy change that occurs when an electron is acquired by a neutral atom
When most atoms acquire an electron…
They release energy
Electron Affinity Trends
In a period, values generally become more negative. Exception is noted between 14 and 15 (single electron vs. putting in second electron in orbit). Going down a group is typically more difficult to add electrons, but nuclear charge and atomic radii play a role.
