What did Cannizzaro Do? Developing a method that led to the determination of standard relative atomic masses, which allowed chemists to search for periodic trends among elements . History of the Periodic Table. What did Mendeleev do?. Discovered the periodic law
Discovered the periodic law
Organized the elements according to increasing atomic mass and noticed that similar properties appeared periodically.
What is the periodic law?
The physical and chemical properties of the elements are periodic functions of their atomic numbers
Demostrated in the periodic table because groups have similar chemical and physical properties and behavior
The configurations of the outermost electron shells of elements within the same group are the same. There are a number of exceptions to this rule, in the transition elements
The length of a period is determined by the total number of electrons that can fill the outer sublevel of the elements of that period
What is the relationship between the electron configuration of an element and the periods in which that element appears in the periodic table
An element’s period corresponds to its highest occupied main energy level.
The type of sublevel being filled in successive elements of that block
S block: groups 1 and 2
P block: groups 13-18 except He(s)
D block: groups 3-12
F block: lanthanide and actinide series
Nonmetals at the right
Metalloids on the stairs
Metals under the stairs: these metals are generally ahrder and more dense than the s block metals but softer and less dense than the d-block metals
Most reactive nonmetals
Fluorine is the most reactive of all nonmetals
React vigorously with most metals to form salts
Most electronegative elements.
Mostly brittle solids with electrical conductivities intermediate between those of metals (good conductors) and nonmetals (poor conductors)
s and p group elements
Decrease in atomic size
Increase in ionization energy
Increase in electron affinity
Decrease in cationic size
Decrease in anionic size
Increase in electronegativity
What is ionization?
Any process that results in the formation of bonded atoms
What is first ionization energy?
The energy required to remove one electron from a neutral atom of an element.
What is second ionization energy?
The energy required to remove an electron from a 1+ ion.
Increase across a period and decrease down a group.
Across a period, the increasing nuclear charge more strongly attracts electrons in the same energy level and makes them more difficult to remove
Down a group, the electrons to be removed from each successive element are in increasingly higher energy levels farther from the nucleus and are more easily removed
The energy taken in or given off when an electron is added to an atom
Electron affinity values are either negative or positive. A negative sign shows that energy is given off and a positive sign show energy is taken in
Cation: positive ion and a metal
Anion: negative ion and a nonmetal
Cations are always smaller than the atoms they came from
Anions are always larger than the atoms they came from