Consider the positions of barium (ba), sulfur (s), silicon (si), and calcium (ca) on the periodic table. the atoms of which element require the least amount of energy to give up an electron when forming chemical bonds?

Element      atomic number       position

Ba              56                             group 2, period 6

Ca              12                             group 2, period 3

S                16                             group 16, period 3

Si               `14                            group 14, period 3

Now, you need to know the properties of the different type of elements and the tendencies on the periodic table.

The metallic elements are, those placed on the left side of the periodic table, are the ones that release an electron more easily, so they will requiere less energy to give it up when forming chemical bonds.

The higher the metallic character the less the energy need to give up an electron.

The metallic character grows as the group number decreases (goes to the left) period increases (goes downward), so among the  elements considered, Barium will require the least amount of energy to give un an electron when forming chemical bonds.

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

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