Unit 1 Periodic Table Reading Assignment

Primary substances , called ____________________ , build all the materials around you . There are more than 109 different ____________________ known today . The ____________________ are composed of ____________________ , the smallest units that are characteristic of a particular ____________________ . Some ____________________ occur in different forms , such as graphite and diamond for the ____________________ carbon . But whatever the form of the ____________________ , it is composed of its characteristic ____________________ .

____________________ are made of even smaller particles of matter called subatomic particles . A large number of subatomic particles are now known , but we are primarily interested in the ____________________ ( p ) , ____________________ ( n ) , and ____________________ ( e ) . ____________________ are ____________________ charged particles ( + ____________________ ) , ____________________ are ____________________ charged particles ( ? 1 ) , and ____________________ are ____________________ ( charge = ____________________ ) .

Atoms of a particular element have one feature in common : the number of ____________________ in the nucleus . The number of ____________________ , called the ____________________ ____________________ ( Z ) is unique for each element . Atoms of the element hydrogen always have ____________________ proton in their nuclei , while atoms of the next element , helium , always have ____________________ protons in their nuclei . Atoms of the element carbon similarly contain ____________________ protons , and atoms of iron have ____________________ protons . The sum of the number of protons and neutrons in the nucleus of an atom is called the ____________________ ____________________ .

The ____________________ ____________________ is a listing , in chart form , of the known elements . Long ago , it was recognized that certain ____________________ shared similar ____________________ , and when the property , such as density , was plotted against atomic mass , a repeating , or " periodic " pattern was observed . The modern periodic table is arranged in horizontal rows ( also called ____________________ ) and vertical columns called ____________________ or families . The ____________________ are numbered from 1 to 7 . The ____________________ are numbered 1 through 18 , excluding the lower , separate rows of elements ( the lanthanides and actinides ) below the main table .