Which one remains the same throughout a period?
Correct answer: C. Number of shells (orbits)
- A. Atomic radius
- B. Melting point
- C. Number of shells (orbits)
- D. Electrical conductivity
Explanation
Across a period, the atomic number increases, which means the number of protons increases in the nucleus. This results in the increased positive charge of the nucleus, which attracts the electrons more strongly towards the nucleus. This results in a decrease in atomic size (atomic radius) and an increase in the ionization energy and electron affinity of the elements.Melting point and electrical conductivity vary across a period due to the different bonding patterns and arrangements in the elements. In contrast, the number of shells or orbits remains the same across a period since the elements in a period have the same number of electron shells. Therefore, correct option is number of shells.
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About Periodic Properties and Trends
Periodic properties arise from electron configuration and effective nuclear charge, producing trends in atomic and ionic radius, ionization energy, electron affinity, electronegativity, metallic character and reactivity. Comparisons run across periods and down groups, with attention to common exceptions. The topic also relates these trends to the behavior of s-block and p-block elements.
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