How is the structure of the atom related to the organization of the modern periodic table?

Atoms have energy levels for its electrons. In most cases, those levels fill up from the ground up. Each energy level contains a fixed number of electrons. The number of electrons in a neutral atom of a certain element is also definite. As a result, the number of energy levels those electrons occupy in a ground state atom is certain for an element.

As its name suggests, the periodic table has multiple rows known as periods. Atoms of elements in the same row have the same number of occupied energy levels per atom. This is true only when the atom is neutral and in its ground state.

For example:

Among all occupied energy levels, the level with the highest energy is known as the valence shell. The number of electrons in that level in a neutral atom could predict chemical properties of the atom.

The periodic table is divided into columns. Each column is known as a group. Elements in each group has the same number of electrons in their valence shell. Again, this holds only if the atom is neutral and in its ground state. As a result, elements in each group have similar chemical properties.

For example, both Na and K are found in the leftmost column of the periodic table. Both are group 1 elements. The two elements have similar chemical properties:

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2