You know the periodic table that hung on the wall of every science class you took at school? As of today, it’s wrong. Or more precisely, it's inaccurate.

Chlorine is a halogen in group VII A of the periodic table with atomic number 17, an atomic weight of 35.45, and a density of 1.56 Mg/m 3. In the solid state it forms a tretragonal crystal with a ...

Predictive power. Gallium. Mendeleev left blank spaces in his original periodic table so that he could properly line up the known elements. Gallium, element 31, was his first gap to be filled, in ...

The periodic table is a chart of all the elements arranged in increasing atomic number. Group 1 alkali metals. ... The three common Group 7 elements are chlorine, bromine and iodine.