H - hydrogen
Li - lithium
Na - sodium
K - potassium
Rb - rubidium
Cs - cesium
Fr - francium
These elements are in the first main group because they only have one valence electron, which is located in an s orbital.
The atomic size increases from H to Fr.
The ordinal number increases from H to Fr.
The mass number increases from H to Fr.
The reactivity increases from H to Fr.
The melting point drops from Li to Fr.
The boiling point drops from Li to Fr.