Zn(s) + HCl(aq) → ZnCl2(s) + H2(g)

Hey there!

Assuming you want us to balance the equation:

Zn + HCl → ZnCl₂ + H₂

Balance Zn.

1 on the left, 1 on the right. Already balanced.

Balance H.

1 on the left, 2 on the right. Add a coefficient of 2 in front of HCl.

Zn + 2HCl → ZnCl₂ + H₂  

Balance Cl.

2 on the left, 2 on the right. Already balanced.

Our final balanced equation:

Zn + 2HCl → ZnCl₂ + H₂  

Hope this helps!

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.