Question

Explain the electronegativity trends across a row and down a column of the periodic table. Compare these trends with those of ionization energies and atomic radii. How are they related?

Short answer

Electronegativity increases across a period (row) and decreases down a group (column) in the periodic table, similar to ionization energy trends. Conversely, atomic radii decrease across a period and increase down a group. The increase in electronegativity and ionization energy across a period is due to decreasing atomic radii and higher effective nuclear charge experienced by the outer electrons. The trends show the interdependent relationships between electronegativity, ionization energy, and atomic radii in the periodic table.

Step-by-step solution

Electronegativity Trends

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. As we move across a period (row) from left to right in the periodic table, the electronegativity generally increases. On the other hand, as we move down a group (column), the electronegativity decreases.

Ionization Energy Trends

Ionization energy is the energy required to remove an electron from an atom to form a positive ion. Similar to electronegativity, ionization energy also increases across a period and decreases down a group. This is because as we move across a period, the atomic radii decrease, making it more difficult to remove an electron, and so the ionization energy increases. In contrast, as we move down a group, the atomic radii increase, making it easier to remove an electron, and thus causing the ionization energy to decrease.

Atomic Radii Trends

Atomic radii refer to the sizes of the atoms. Going across a period, atomic radii decrease due to the increase in the effective nuclear charge experienced by the outer electrons, caused by the increased number of protons and similar shielding by inner electrons. Moving down a group in the periodic table, atomic radii increase due to the addition of electron shells, which cause the increase in atomic size.

Relationship Between Electronegativity, Ionization Energy, and Atomic Radii

Electronegativity trends and ionization energy trends are positively correlated across a period and down a group in the periodic table. As atomic radii decrease across a period, the effective nuclear charge increases, making the atom more likely to gain electrons (higher electronegativity) and harder to remove an electron (higher ionization energy). Similarly, as atomic radii increase down a group, it is easier for the atom to lose an electron (lower ionization energy) and less likely to gain an electron (lower electronegativity). In summary, electronegativity and ionization energy both increase when moving across a period and decrease when moving down a group due to the changes in atomic radii. These trends show the interdependent relationships between electronegativity, ionization energy, and atomic radii in the periodic table.