Can someone name an element that doesn’t match its abbreviation?

Gold, silver and sodium.

Explanation:

Gold, silver and sodium are the name of the elements which does not match to their abbreviation. It is because those names are comes from other language. For example, the symbol of sodium is Na which comes from Natrium that is a Latin word. The symbol of gold is Au which comes from Aurum that is also a Latin word. The symbol of silver is Ag which comes from a Latin word i. e. Argentum.

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer