Difficulty: Easy

Average Score: 91%

On the periodic table, elements in the same row are arranged from left to right by

Rationale

Elements in the same row of the periodic table are arranged from left to right by an increasing number of protons in an atom's nucleus.

The periodic table is structured in rows (periods) where each element has one more proton than the element preceding it. This increasing proton count defines each element's atomic number, which directly influences its chemical properties and position on the table.

A (an increasing number of neutrons in an atom's nucleus) YOUR ANSWER

Neutrons do not dictate the arrangement of elements in the periodic table. While isotopes of an element can have different neutron counts, the periodic table is primarily organized based on atomic number, which reflects the number of protons rather than neutrons.

B (a decreasing number of neutrons in an atom's nucleus) YOUR ANSWER

Similar to choice A, this option is incorrect because the arrangement of elements does not involve neutrons. Neutron counts can vary widely among isotopes of the same element without affecting the element's sequential position on the periodic table.

C (an increasing umber of protons in an atom's nucleus) CORRECT

This choice accurately describes how elements are organized in a row of the periodic table. Each successive element has one more proton than the previous one, which is fundamental to their classification and determines their identity as distinct elements.

D (a decreasing number of protons in an atom's nucleus) YOUR ANSWER

This statement is false, as elements in the same row are ordered by an increasing number of protons. A decreasing proton count would imply a regression in atomic number, which contradicts the established ordering principle of the periodic table.

Conclusion

The periodic table's organization into rows is based on the increasing number of protons in an atom's nucleus, reflecting the atomic number of each element. This systematic arrangement allows for the prediction of chemical behavior and properties, reinforcing the fundamental relationships among different elements. Neutron numbers, while important in defining isotopes, do not influence their position on the periodic table.

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