Unit 1 Section 1: Atomic Structure

Question 1

What is the first stage of mass spectrometry?

Answer 1

electrospray ionisation: the sample is dissolved in a polar solvent and pushed through a small nozzle at high pressure. A high voltage is applied and an electron is removed, leaving positive ions in a gas.

Question 2

What is the second stage of mass spectrometry?

Answer 2

Acceleration: the ions are accelerated by an electric field. All ions are given the same kinetic energy but ions with greater mass/charge ratio accelerate slower.

Question 3

What is the third stage of mass spectrometry?

Answer 3

Ion drift: the ions leave the field with constant kinetic energy. They enter a region with no electric field and drift through at constant speeds. The lighter ions drift faster.

Question 4

What is the last stage of mass spectrometry?

Answer 4

Detection: the ions hit a metal plate, which detects the current created by the charged ions. It records how long they took to pass through the spectrometer.

Question 5

What 2 measurements are recorded for each isotope in a mass spectrometer?

Answer 5

m/z (mass/charge), relative abundance

Question 6

State why isotopes of the same elements have the same chemical properties

Answer 6

Their electronic configuration is the same

Question 7

Write an equation, including state symbols, for the reaction that occurs when the first ionisation energy of carbon is measured.

Answer 7

C(g)->C+(g)+e-

Question 8

Give the definition of relative atomic mass

Answer 8

The average mass of an atom on a scale where carbon-12 is exactly 12