Why do the last 18 elements in the periodic table have names starting with Un... ?

A series of elements present at the end of the Periodic Table have names that start with the two letters Un... These elements are:

Name of element	Atomic number
Unnilunium	101
Unnilbium	102
Unniltrium	103
Unnilquadium	104
Unnilpentium	105
Unnilhexium	106
Unnilseptium	107
Unniloctium	108
Unnilennium	109
Ununillium	110
Unununnium	111
Ununbium	112
Ununtrium	113
Ununquadium	114
Ununpentium	115
Ununhexium	116
Ununseptium	117
Ununoctium	118

Why do these elements all start with Un.. ?

All these elements starting with Un... have atomic number greater than 100. These elements cannot occur naturally. They can only be obtained by the artificial transmutation of elements.

Each of these elements were discovered by many scientists worldwide. It has not been confirmed who discovered them first. Since all the scientists who discover an element name it according to them, the names of these elements could not be established as their discovery is yet controversial. For example, the element with atomic number 104 (Unnilquadium) was only recently discovered by both American and Soviet scientists. The American scientists called it "Rutherfordium" but the Soviet scientists called it "Kurchavotium".

In order to avoid confusion, the IUPAC (International Union of Pure and Applied Chemistry) has decided that these elements should be named according to a set of rules until their discovery is confirmed.

The set of rules, or the naming convention for these elements are as follows:

Rules for the name of the element

• Each element will be named by the use of "roots" according to the atomic number of the element. Each "root" will denote a particular number as follows:

Number:	0	1	2	3	4	5	6	7	8	9
Root:	nil	un	bi	tri	quad	pent	hex	sept	oct	enn

• For example, the fourth element with atomic number 104 will be named as follows:
• From the digits 104,
• 1 is for "un"
• 0 is for "nil"
• 4 is for "quad"
• So we get "unnilquad"
• The first letter will be made capital, so we get "Unnilquad"
• Each element's name will be followed by "ium", so we get "Unnilquadium".

Rules for the symbol of the element

• The symbol for the element will be the first letters of each of the roots used in its name.
• For example, the roots used in the name of Unnilquadium are un, nil and qaud. Taking the first letter of each of these roots, we get "unq".
• The first letter of the symbol obtained above will be made capital. So we get "Unq".
• Therefore the symbol for element Unnilquadium with atomic number 104 is "Unq".

Special conditions in naming

Sometimes special conditions arise in the above naming convention. These are as follows:

• If enn occurs before nil, the second n of enn will be dropped.
• If bi occurs before ium, the i of bi should be dropped.
• If tri occurs before ium, the i of tri should be dropped.