Which property is the same for elements within the same group?

Which property is the same for elements within the same group?

• A. Atomic number
• B. Electrons in outer shell
• C. Mass number
• D. Protons in nucleus

Answer: (B)

The number of electrons in the outer shell is the property that stays the same for elements in a group. In the periodic table, elements in the same vertical column share the same valence electron count, which is what largely determines how they bond and react. That’s why elements in a group behave similarly chemically. As you go down a group, the overall number of protons and the total electrons in the atom increase, so the atomic number changes and the mass number can vary with different isotopes. But the outer-shell electron count remains constant for main-group elements, so the shared chemical characteristics persist. For example, elements with one electron in the outer shell (alkali metals) all react similarly, while those with seven outer electrons (halogens) show a related pattern.

The number of electrons in the outer shell is the property that stays the same for elements in a group. In the periodic table, elements in the same vertical column share the same valence electron count, which is what largely determines how they bond and react. That’s why elements in a group behave similarly chemically.

As you go down a group, the overall number of protons and the total electrons in the atom increase, so the atomic number changes and the mass number can vary with different isotopes. But the outer-shell electron count remains constant for main-group elements, so the shared chemical characteristics persist. For example, elements with one electron in the outer shell (alkali metals) all react similarly, while those with seven outer electrons (halogens) show a related pattern.