2
electrons in each shell: 2,8,18,18,8,2
Look on the periodic table of elements. Barium is in the 2nd column. All elements in the 2nd column have a charge (valence Number) of +2. The have 2 electrons in their outer shell.
6
1
2 valence electrons
Barium has 56 electrons.
Valences of einsteinium are 2, 3 and 4.
The valences of polonium are 2, 4 and 6.
the answer is 28
Barium is monatomic so 56.
Barium has 56 protons.
Fluorine is an element and barium is also an element. There is no fluorine in barium and not barium in fluorine.
Many elements have two or more valences.