Periodic Trends
How atomic radius, ionization energy, electronegativity and other properties change across the periodic table, and why.
Atomic Radius
How large an atom is, measured here as van der Waals radius — the effective size an atom occupies when it isn't chemically bonded to anything.
First Ionization Energy
The energy needed to remove the single most loosely held electron from a neutral, gas-phase atom.
Electronegativity
How strongly an atom pulls shared electrons toward itself when it's bonded to another atom.
Electron Affinity
The energy change when a neutral, gas-phase atom gains one extra electron — how much an atom "wants" an additional electron.
Melting Point
The temperature at which an element turns from solid to liquid at standard pressure.
Boiling Point
The temperature at which an element turns from liquid to gas at standard pressure.
Density
Mass per unit volume at standard conditions — how tightly an element's atoms are packed together.
Atomic Mass
The average mass of one atom, in atomic mass units — driven almost entirely by proton and neutron count.