8.3 Identification of ions by chemical and spectroscopic means

• What are ions formed by?

  Gaining or losing electrons
• Positive ions are called cations.


  True
• A calcium atom loses two electrons to form Ca2+
• Ions are atoms that have gained or lost electrons
• What is the charge of a calcium ion (Ca2+)?

  Positive
• What precipitate is formed when silver nitrate reacts with chloride ions?

  Silver chloride
• Match the pH level with the litmus paper color change:

  Acidic ↔️ Blue litmus turns red

  Basic ↔️ Red litmus turns blue
• What flame color does sodium produce in a flame test?

  Yellow
• Litmus paper tests indicate pH
• Atomic Emission Spectroscopy (AES) excites atoms by heat to emit light at specific wavelengths
• Spectroscopic techniques are highly sensitive and accurate for ion identification.


  True
• What is the process of gaining or losing electrons called?

  Ionization
• Match the ion type with its definition:

  Cation ↔️ Positive ion formed by losing electrons

  Anion ↔️ Negative ion formed by gaining electrons
• Which cation is formed when a sodium atom loses one electron?

  Na+
• What is the charge of a chloride ion (Cl-)?

  Negative
• Silver nitrate (AgNO3) reacts with chloride ions (Cl-) to form silver chloride (AgCl) precipitate.


  True
• Litmus paper changes color depending on the pH
• Copper (Cu2+) absorbs light at a wavelength of 324.8
• Spectroscopic techniques are highly sensitive and accurate for ion identification.


  True
• Spectroscopic techniques rely on the unique light emission or absorption patterns of ions when they interact with electromagnetic radiation
• What color of light does sodium (Na+) emit in Atomic Emission Spectroscopy?

  Yellow
• Spectroscopic techniques can provide quantitative data about ion concentrations.


  True
• What type of information do chemical methods primarily provide about ions?

  Qualitative
• Spectroscopic methods are more time-consuming and may require specialized equipment.


  True
• Detecting chloride ions (Cl-) in water involves adding silver nitrate to form a white silver chloride (AgCl) precipitate
• Testing the acidity of a river water sample using litmus paper involves observing a change from blue to red
• When an atom loses electrons, it becomes a cation
• What charge does a sodium ion (Na+) have?

  Positive
• Anions are formed when atoms gain electrons.


  True
• What is the charge of a sulfide ion (S2-)?

  Negative
• Cations are negative ions.

  False
• Match the ion with its definition:

  Cation ↔️ Positive ion formed by losing electrons

  Anion ↔️ Negative ion formed by gaining electrons
• A chloride ion (Cl-) is formed when a chlorine atom gains one electron
• Cations and anions have opposite charges.


  True
• Steps for performing a precipitation reaction

  1️⃣ Mix solutions containing the ions with reagents

  2️⃣ Observe the formation of a precipitate

  3️⃣ Confirm the presence of the ion
• In a flame test, different ions produce distinctive flame colors
• Bases turn red litmus paper blue.


  True
• Spectroscopic methods rely on the unique light emission or absorption patterns of different ions
• Match the method with its outcome:

  Precipitation Reactions ↔️ Insoluble precipitate formation

  Flame Tests ↔️ Distinctive flame colors

  Litmus Paper Tests ↔️ Color changes based on pH
• Spectroscopic methods rely on the unique light emission or absorption patterns of ions when they interact with electromagnetic radiation.


  True