Mass Number and Isotopes

Question 1

what is mass number and atomic number

Answer 1

mass number = number of protons + neutrons
Atomic number = number of protons

Question 2

How does a Time Of Flight mass spectrometer work

Answer 2

First we take a sample of the element an place it in the sample chamber

Atoms go through ionisation and now become positive ions

Hence they get attracted to the negative plate witch causes them to accelerate and therefore increase in Kinetic energy

ions stop accelerating and drift through chamber towards the detector

note : All ions with same charge have same Kinetic energy
Lighter ions move faster than heaver ions

ions reach detector and gain electrons
this transfer of electrons causes current to flow

higher the current the more abundant the isotope

Time taken to move down chamber used to get the mass of the isotope

Note : Chamber is a vacuums to stop ions colliding with air particles

Question 3

What is an Isotope

Answer 3

Atoms of the same element with same number of protons but different mass number ( different number of neutrons )

Question 4

Why is Mass Spectrometry Used

Answer 4

Its used to identify elements - Compare results to a database

Can be used to determine relative molecular mass

Question 5

Why do isotopes have same chemical properties

Answer 5

because they have the same electronic configurations.

Question 6

Why is the mass spectometer in a vaccume

Answer 6

To prevent air molecules from blocking the ions path , they will collide