Unit 4 Chapter 5: History of the Periodic Table

Cannizzaro

presented a method for accurately measures atomic masses of atoms

Mendeleev

arranged the 63 known elements by increasing atomic mass

Moseley

organized elements according to increasing atomic number

Periodic Law

the physical and chemical properties of the elements are periodic functions of their atomic numbers

A group elements

main group or representative elements; s & p blocks

B group elements

transition metals; d block

atomic radius (periodic table)

decreases across a period, increases down a group

ionization energy (periodic table)

increases across a period, decreases down a group

electronegativity (periodic table)

increases across a period, decreases down a group

ion configuration

electron configuration, but +/- the lost/gained electrons

period

horizontal rows across the periodic table

group/family

vertical columns on the periodic table

f block

inner transition metals

noble gases

group 8A (VIIIA); full valence electrons

metalloids

-found lining the staircase -have properties of both metals and non-metals -semiconductors of electricity

ion

particle with a non-neutral (+ or -) charge

cation

positive ion (+); electrons are lost

anion

negative ion (-); electrons are gained

atomic radius

half of the distance between nuclei in covalently bonded diatomic molecules

ionic radii (+)

cations formed when metal atom loses one or more electrons, increases electronegativity

ionic radii (-)

anions formed when nonmetallic atoms gain one or more electrons, decreases electronegativity

neutral vs cation

cations are smaller than their corresponding neutral atom

neutral vs anion

anions are bigger than their corresponding neutral atom

ionization energy

the energy required to remove an electron from an atom

electronegativity

a measure of the ability of an atom in a chemical compound to attract (gain) electrons

ion configuration

electron configuration + or - electrons gained/lost

properties of metals

-located to the left of the staircase -good conductor of heat and electricity -malleable -ductile -high tensile strength -luster

properties of alkali metals

-easily lose valence electron -most reactive metal group -never found pure in nature -react violently with water

properties or alkaline-earth metals

-less reactive than alkali metals -never found pure in nature -loses two valence electrons

properties of non-metals

-located to the right of the staircase -poor conductors of heat and electricity -brittle -many are gases at room temperature

properties of halogens

-react vigorously with most metals to form salts -most reactive non-metal group