Trends

Electronegativity:
- Trend: Increases from left to right.
- Reason: As you move across a period, the number of protons in the nucleus increases, leading to a higher nuclear charge. This increased positive charge attracts the bonding electrons more strongly, increasing the element's electronegativity.
Ionization Energy:
- Trend: Increases from left to right.
- Reason: Similar to electronegativity, the increasing nuclear charge across a period means that electrons are held more tightly by the nucleus. Consequently, more energy is required to remove an electron, resulting in higher ionization energy.
Atomic Radius:
- Trend: Decreases from left to right.
- Reason: Despite the addition of more electrons as you move across a period, these electrons are added to the same principal energy level. The increased nuclear charge pulls the electron cloud closer to the nucleus, reducing the atomic radius.

Electronegativity:
- Trend: Decreases from top to bottom.
- Reason: As you move down a group, electrons are added to higher energy levels farther from the nucleus. The increased distance and additional shielding by inner-shell electrons reduce the effective nuclear charge experienced by the valence electrons, thus decreasing electronegativity.
Ionization Energy:
- Trend: Decreases from top to bottom.
- Reason: With increasing atomic number down a group, electrons are added to higher energy levels. These outer electrons are farther from the nucleus and are more shielded by inner electrons, making them easier to remove. Hence, ionization energy decreases.
Atomic Radius:
- Trend: Increases from top to bottom.
- Reason: Each successive element down a group has an additional electron shell compared to the one above it. This increased number of energy levels leads to a larger atomic radius, even though the nuclear charge increases because the effect of increased distance and electron shielding outweighs the effect of increased nuclear charge.