As you move across the periodic table, each element has one more proton than the last:

• Hydrogen (1) to Helium (2) — the lightest gases, formed in the Big Bang
• Carbon (6) to Oxygen (8) — the backbone of life, forged in massive stars
• Iron (26) — the last element a star can fuse for a net energy gain, which is why massive stars die once their core turns to iron
• Gold (79) and Platinum (78) — formed in neutron star collisions, the most violent events in the universe
• Uranium (92) — the heaviest naturally occurring element, with a nucleus so packed with protons that it is barely stable