Write the atomic symbol (including the atomic number) for an isotope with 54 protons and 78 neutrons.

132 54Xe

Explanation:

From the question given above, the following were obtained:

Proton = 54

Neutron = 78

Atomic number =?

Atomic symbol =.?

Next, we shall determine the atomic number of the isotope. This can be obtained as follow:

Atomic number of an element is simply defined as the number of protons in the atom of the element.

Thus,

Atomic number = proton number

Proton = 54

Atomic number = proton number = 54

Atomic number = 54

Therefore, the atomic number of the isotope is 54

Next, we shall determine the mass number of the isotope. This can be obtained as follow:

Proton = 54

Neutron = 78

Mass number =.?

Mass number = Proton + Neutron

Mass number = 54 + 78

Mass number = 132

Therefore, the mass number of the isotope is 132.

From the calculations made above, the isotope have:

Atomic number = 54

Mass number = 132

Comparing the atomic number with those in the periodic table, the isotope is Xenon (Xe).

Thus, the atomic symbol for the isotope is 132 54Xe.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.