| A | B |
|---|
| Johann Dobreiner | noticed sets of 3 elements with similar properties |
| triad | group of 3 elements found by Dobreiner to have similar properties |
| John Newlands | when he ordered elements by atomic mass noticed the law of octaves |
| law of octaves | when ordered by increasing atomic mass every 8th element repeats properties of the first |
| Dimitri Mendeleev | developed periodic law based on atomic mass |
| original periodic law | physical and chemical properties are a periodic function of atomic mass |
| Henry Moseley | developed modern periodic law based on atomic number |
| modern periodic law | physical and chemical properties of elements are a periodic function of atomic number |
| period or series | horizontal row in periodic table |
| family or group | vertical column in periodic table |
| elements with same number of valance electron | family or group |
| elements with elecrons with the same outermost energy level having at least 1 electron | period or series |
| transition elements | name given to elements in groups 3 through 12 |
| alkali metals | name given to elements of group 1 |
| alkaline earth metals | name given to elements of group 2 |
| nitrogen family | name given to elementss of group 15 |
| oxygen family | name given to elements of group 16 |
| halogen family | name given to elements of group 17 |
| noble gases | name given to elements of group 18 |
| lanthanides | transitional elements in period 6 with atomic numbers 57-71 |
| actinides | transitional elements in period 7 with atomic numbers 89-103 |
| ionization energy | energy needed to remove the most loosely held elecron from the outer energy level of an atom in the gas phase |
| valence shell | outermost energy level containing electrons |
| valence electrons | electrons occupying the outermost energy level of an atom |
| law of octets | to be stable atoms will gain or lose electrons to have their valence shell hold 8 electrons |
| sheilding effect | attractive force of nucleus is lessened as atomic radius increases because inner kernel electrons repel outer valence electrons |
| how does ionization energy change going down a family | it decreases |
| how does the ionization energy change from left to right in a period | it increases |
| electronegativity | a measure of the ability of an atom to attract elements to itself |
| how does electronegativity change goind down a family | it decreases |
| how does electronegativity change from left ot right in a period | it increases |
| covalent atomic radius | distance between the nucleus and valence shell in an atom that is covalently bonded |
| van der Waals radius | half the distance between the nuclei of identical atoms at their point of closest approach when no bond is formed |
| how does the atomic radius change from left to right in a period | it decreases |
| how does the atomic radius change reading down a family | it increases |
| ionic radius | distance from nucleus of a monoatomic ion to its valence shell |
| isoelectric species | atoms or ions with the same electron configuration |
| how does metallic charater change moving down a family | it increases |
| how does metallic character change moving from left to right in a period | it decreases |
| where in the periodic table are the metals found | left side of the table |
| where in the periodic table are the nonmetals found | right side of the table |
| where are the metalloids found in the periodic table | in the "staircase" that goes down grups 13 through 17 |
| what is similar about Si, Ge, As, Sb, Te, and At | metalloid element |
| how does melting point change going down a family | it decreases |
