What is a period in a periodic table ? How do atomic structures (electron arrangements) change in a period with increase in atomic numbers from left to right ?

Question

Philoid · Accepted Answer

Periods are the horizontal rows present in the periodic table. As we move from left to right in a period, the atomic number of elements increases which means that the no. of protons and electrons in the atom increases. Due to large positive charge on the nucleus, the electrons are pulled in more close to the nucleus and the size of the atom decreases.