4.3.1 Trends Across Period 3

• Aluminium does not react with water under normal conditions due to a protective oxide
• Period 3 elements exhibit a trend of increasing electronegativity and ionization energy.
• What are Period 3 elements defined as in the periodic table?

  Third horizontal row
• Period 3 elements include Sodium, Magnesium, and Argon.
• One of the key trends across Period 3 is increasing electronegativity
• What happens to ionization energy across Period 3?

  Increases
• Period 3 elements transition from metallic to non-metallic properties.
• Match the Period 3 element with its chemical symbol:

  Sodium ↔️ Na

  Magnesium ↔️ Mg

  Aluminium ↔️ Al

  Silicon ↔️ Si
• Which Period 3 element is classified as an alkali metal?

  Sodium
• Magnesium is an alkaline earth metal.
• What type of element is Aluminium in Period 3?

  Metal
• Period 3 elements include Sodium, Magnesium, Aluminium, Silicon, Phosphorus, Sulfur, Chlorine, and Argon
• The electronegativity of Period 3 elements increases from left to right.
• What type of metal is Sodium?

  Alkali metal
• What is the atomic number of Magnesium?

  12
• What type of element is Aluminium?

  Metal
• The transition from metallic to non-metallic properties occurs across Period 3
• Which Period 3 element is classified as a metalloid?

  Silicon
• What type of element is Phosphorus?

  Nonmetal
• What do Period 3 elements refer to in the periodic table?

  Elements in the third row
• The Period 3 element with the symbol $Na$ is called sodium
• Electronegativity increases across Period 3
• Order the following Period 3 elements by increasing atomic number:

  1️⃣ Sodium

  2️⃣ Magnesium

  3️⃣ Aluminium

  4️⃣ Silicon

  5️⃣ Phosphorus

  6️⃣ Sulfur

  7️⃣ Chlorine
• Which type of metal is sodium in Period 3?

  Alkali metal
• The Period 3 element classified as a metalloid is silicon
• Match the Period 3 element with its property:

  Sodium ↔️ Alkali metal

  Magnesium ↔️ Alkaline earth metal

  Chlorine ↔️ Halogen
• The electron configuration for Period 3 elements is determined by filling the 3s and 3p orbitals
• What is the electron configuration of sodium?

  $1s^{2} 2s^{2} 2p^{6} 3s^{1}$
• The electron configuration of magnesium is 1s^{2} 2s^{2} 2p^{6} 3s^{2}</latex>
• What is the electron configuration of aluminium?

  $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{1}$
• What does the electron configuration of an element describe?

  Electron distribution in orbitals
• For Period 3 elements, the electron configuration can be determined by filling the 3s and 3p orbitals
• What is the electron configuration of sodium?

  $1s^{2} 2s^{2} 2p^{6} 3s^{1}$
• What is the electron configuration of magnesium?

  $1s^{2} 2s^{2} 2p^{6} 3s^{2}$
• The electron configuration of aluminum is 1s^{2} 2s^{2} 2p^{6} 3s^{2}3p^{1}</latex>
• What is the electron configuration of silicon?

  $1s^{2}2s^{2} 2p^{6} 3s^{2} 3p^{2}$
• What is the electron configuration of phosphorus?

  1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{3}</latex>
• What is the electron configuration of sulfur?

  $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{4}$
• What is the electron configuration of chlorine?

  $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{5}$
• The 3s orbital is filled before the 3p orbital in electron configurations for Period 3 elements