Explanation:
A column on the periodic table represents a period. 
These are some of the variations observed across a period; 
- Atomic radii decreases progressively from left to right due to the progressive increase in the nuclear charge without an attendant increase in the number of electronic shells. 
- Ionization energy increases progressively from left to right due to decreasing atomic radii. 
- Electronegativity increases from left to right. 
- Electropositivity decreases across a period.