"Hydrogen makes up two of the three atoms in water. Hydrogen gas is not toxic but is dangerous if
mixed with air or oxygen."
"Hydrogen was discovered to be an element in 1776. It was discovered to by a man named Henry Cavendish
in London, England."
"The standard state of hydrogen is gas at 298k and it is the lightest gas known."
"If the elements are listed in order of increasing atomic #, there will be a pattern(trend) to the
same property. Since this pattern repeats, it is called "periodic."
"Every element on the periodic table has traces of helium in it."
"Mendeleev's mother was the only person in his family to support his scientific discoveries."