why is cesium larger than barium?

Answer 1

Cesium - atomic number 55
Number of Protons/Electrons: 55
Number of Neutrons: 78
Number of Energy Levels: 6
First Energy Level: 2
Second Energy Level: 8
Third Energy Level: 18
Fourth Energy Level: 18
Fifth Energy Level: 8
Sixth Energy Level: 1

Barium - atomic number 56
Number of Protons/Electrons: 56
Number of Neutrons: 81
Number of Energy Levels: 6
First Energy Level: 2
Second Energy Level: 8
Third Energy Level: 18
Fourth Energy Level: 18
Fifth Energy Level: 8
Sixth Energy Level: 2

There is one more electron on the outer energy level in barium. It has also more neutrons. So it is "bigger"

Answer 2

Cesium has the atomic number 55, meaning it has 55 protons and 55 electrons.

Barium has an atomic number of 56, so based on that, it has 56 protons and 56 electrons.

The period table has a trend called "Atomic Radius". The atomic radius is the distance from the center of the of the atom's nucleus to it's outer most electron. The atomic radius gets smaller as you go left to right on a period. The periods are the 7 rows of the table and in your case, from Cesium to Radon.

The radius, or size, gets smaller because of the pull on the electrons. One electron is 2000 times smaller than the smallest element, Hydrogen, and that's pretty small! The protons are much bigger than the electrons, and as you increase in atomic number, you increase in protons, and as you go from left to right on the periodic table, you get more protons and more electrons. The protons pull the electrons closer and closer as you get more of the protons.

Cesium has 55 protons and electrons.
Those 55 protons have a pretty strong pull on those electrons, because the 55 protons are bigger than ALL of those electrons, so they pull the electrons close to the center.

Barium has even MORE protons and since electrons are so small, the protons pull even harder to get them closer, because now they have one more electron to pull.

Periodic trend: Atomic Radius: Going along a period, from left to right, the radius of an atom will decrease.

Answer 3

In a certain column of the periodic table of elements, the atomic size increases from top to bottom. This is because the number of shells (energy levels) increases.

Answer 4

Practice, practice, practice.

Answer 5

it is because of their molecular mass and density ^^,