What is an accurate description of a period in the periodic table

The periods of the periodic table are the horizontal rows.

Explanation:

period is a horizontal row of the periodic table

Explanation:

A period in the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor

Feel free o copy and paste

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