1.2.1 Periodicity

• What is periodicity in the context of the periodic table?

  Recurrence of similar properties
• Periodicity occurs because elements in the same group have the same number of valence
• Match the properties exhibiting periodicity with their descriptions:

  Atomic Radii ↔️ Distance from nucleus to outermost electron

  Ionization Energy ↔️ Energy to remove an electron

  Electronegativity ↔️ Ability to attract electrons in a bond
• Atomic radii increase across a period due to increased nuclear charge.

  False
• Why do atomic radii increase down a group in the periodic table?

  Additional energy levels
• Periodicity is largely due to the similarity in the outer electronic
• Match the elements in the second period with their properties:

  Lithium ↔️ Reactive metal

  Boron ↔️ Metalloid

  Oxygen ↔️ Non-metal gas

  Neon ↔️ Noble gas
• Arrange the elements in the second period based on increasing atomic number:

  1️⃣ Lithium

  2️⃣ Beryllium

  3️⃣ Boron

  4️⃣ Carbon

  5️⃣ Nitrogen

  6️⃣ Oxygen

  7️⃣ Fluorine
• Atomic radius is the distance from the nucleus to the outermost electron shell.
• What happens to the atomic radius as you move across a period from left to right?

  It decreases
• Across a period, the atomic radius decreases due to increasing nuclear
• All elements in the same period have the same number of electron shells.
• Which element in the second period has the largest atomic radius?

  Lithium
• The atomic radius decreases across a period due to increasing nuclear charge.
• What is the formula for calculating atomic radius?

  \text{Atomic Radius} = \frac{\text{Diameter}}{2}</latex>
• What effect does a greater nuclear charge have on the atomic radius of an atom?

  Reduces atomic radius
• The atomic radius consistently decreases across the second period due to the increasing nuclear charge.
• The atomic radius is calculated by dividing the diameter by two.
• Why does the atomic radius increase down a group in the periodic table?

  Additional electron shells
• Order the following factors influencing atomic radius from most significant to least significant when moving down a group:

  1️⃣ Increased Number of Electron Shells

  2️⃣ Shielding Effect
• Core electrons shield valence electrons from the full nuclear charge.
• What is periodicity in the periodic table?

  Recurrence of similar properties
• Periodicity occurs because elements in the same group have similar electron configurations.
• Match the elements in the second period with their valence electrons:

  Lithium ↔️ 1

  Beryllium ↔️ 2

  Carbon ↔️ 4

  Fluorine ↔️ 7
• Elements in the same group have the same number of valence electrons.
• What is the definition of atomic radius?

  Distance from nucleus to outermost shell
• Across a period, the atomic radius generally decreases due to increasing nuclear charge.
• The number of electron shells remains constant across a period.
• The atomic radius is the distance from the center of the nucleus to the outermost electron shell
• Across a period, the atomic radius increases from left to right.

  False
• As the number of protons in the nucleus increases, the atomic radius decreases
• Order the elements in the second period by increasing atomic radius:

  1️⃣ Neon

  2️⃣ Fluorine

  3️⃣ Oxygen

  4️⃣ Nitrogen

  5️⃣ Carbon

  6️⃣ Boron

  7️⃣ Beryllium

  8️⃣ Lithium
• The atomic radius consistently decreases from Lithium to Neon
• The equation for atomic radius is: Atomic Radius = Diameter / 2
• Down a group, the atomic radius increases
• Core electrons shield valence electrons from the full nuclear charge.
• Order the alkali metals by increasing atomic radius:

  1️⃣ Lithium

  2️⃣ Sodium

  3️⃣ Potassium

  4️⃣ Rubidium

  5️⃣ Caesium
• Ionization energy increases across a period due to increasing nuclear charge and decreasing atomic size
• Match the element with its ionization energy:

  Lithium ↔️ 520 kJ/mol

  Neon ↔️ 2081 kJ/mol
• The mathematical relationship between ionization energy, nuclear charge, and atomic size is: IE ∝ Nuclear Charge / Atomic Size