Periodic Trends in s and p Block Elements

In the periodic table, properties change predictably across a period (left to right) due to increasing effective nuclear charge (Z_eff), which results from adding protons to the nucleus and electrons to the same principal energy level.

Step 1: Analyze Each Property Trend

Electronegativity: Increases left to right because atoms have greater attraction for electrons.

Effective Nuclear Charge (Z_eff): Increases left to right due to more protons without significant shielding from inner electrons.

Ionization Energy: Generally increases left to right as it becomes harder to remove an electron.

Atomic Size: Decreases left to right due to increased Z_eff pulling electrons closer.

Electron Affinity: Generally becomes more negative (increases in magnitude) left to right, indicating greater energy release when adding an electron.

Shielding Constant (σ): Remains relatively constant across a period since electrons are added to the same shell.

Step 2: Evaluate the Options

Option 1: Electronegativity, Z_eff, ionization energy – all increase left to right.

Option 2: Size decreases, electronegativity increases, σ is constant – not all increase.

Option 3: Size decreases, electron affinity generally increases, electronegativity increases – not all increase.

Option 4: Z_eff increases, σ is constant, size decreases – not all increase.

Final Answer

The correct set is: Electronegativity, Z_eff, ionization energy.

Related Topics

• Periodic Law and Table Organization
• Atomic Structure and Electron Configuration
• Chemical Bonding and Reactivity

Key Formulae and Theory

Effective Nuclear Charge: $Z_{\text{eff}}=Z-\sigma$, where Z is atomic number and σ is shielding constant.

Ionization Energy: Energy required to remove an electron from a gaseous atom.

Electronegativity: Measure of an atom's ability to attract shared electrons (Pauling scale commonly used).