Chapter 2

Question 1

What are the important polyatomic ions ?

Answer 1

Question 2

How is the Mr of an element attained from the Mass spectrometer ?

Answer 2

• the percentage abundance of the isotopes in an element can be found by the use of a mass spectrometer
  Steps:
• the sample is vaporised
• the sample is ionised to form positive ions
• the ions are accelerated - heavy ions move slower
• the ions are detected as a mass-to-charge ratio - each ion produces a signal, so the larger the signal the greater the abundance

Question 3

What is the difference between relative formula and molecular mass ?

Answer 3

• Relative molecular mass is applied to chemicals that have a fixed formula in terms of the number of atoms involved e.g C2H5OH
• relative formula mass is applied to chemicals that use an empirical formula to represent them, e.g CaCl2