Determine electronic configuration

Part 1: Understanding the periodic table
Remember these definitions:


  • Relative atomic mass: The average mass of one atom of the element relative to 1/12 the mass of one atom of carbon-12.
  • Proton number (atomic number): number of protons in one atom of the element.
  • Relative molecular mass: the mass of one molecule of the compound relative to 1/12 the mass of one atom of carbon -12.
  • Isotopes are atoms of with the same number of protons but different number of neutrons.


Now, what you need to do know as well:

nucleus of calcium, periodic table, electronic configuration, o level chemistry, o level chemical bonding


  • The larger number is the relative atomic number (equals to number of proton plus electron). It is also the called mass number or nucleon number
  • The smaller number is the proton (atomic) number. And:
  • Mass number - proton number  =number of neutrons
  • Protons and neutrons are found in the nucleus; electrons are found in the electron shells that orbit round the nucleus.
  • Proton has a charge of +1, electron has a charge of -1, neutron has no charge
  • Relative mass of proton is 1, relative mass of neutron is 1, relative mass of electron is almost 0.
  • For atoms, number of proton = number of electrons
  • For ions, number of electrons= number of protons - charge of ions
  • Electronic configuration depends on number of electrons, so you look at proton number (the smaller number)

Part 2: What is the charge?

Atoms have no charge.

Ions have charge. In general, the following are the charges:

Group I  --> +1
Group II  --> +2
Group III --> +3
Group V --> -3
Group VI --> -2
Group VII --> -1

Part 3: Electronic configuration
For O level chemistry, remember this:
1. First shell, maximum 2 electrons
2. The rest, maximum 8 electrons.

Try these!
Question:  What is the electronic configuration of an oxygen atom?

Thought process:
- atomic number (proton number) = 8
-  first shell 2, left 6 , so 2nd shell 6.

Answer: electronic configuration of oxygen : (2,6)

Question:  What is the electronic configuration of an oxygen ion?

Thought process:
- oxygen is in Group VI. It has a charge of -2.
-for ions, number of electrons = proton number -charge =8-(-2)=10
-  first shell 2, left 8 , so 2nd shell 8.

Answer: electronic configuration of oxygen ion, or O2- : (2,8)

Question:  What is the electronic configuration of a calcium atom?

Thought process:
- atomic number (proton number) = 20
-  1st shell 2, left 18.
   2nd shell 8,left 10
   3rd shell 8, left 2
   4th shell 2.

Answer: electronic configuration of calcium : (2,8,8,2)

Question:  What is the electronic configuration of a calcium ion?

Thought process:
-Calcium is in group II and has a charge of +2
- Number of electrons = proton number - charge =20-(+2)=18
-  1st shell 2, left 16.
   2nd shell 8,left 8.
   3rd shell 8.

Answer: electronic configuration of calcium ion or Ca2+ : (2,8,8)


Related Posts




Related Google App
Find number of electrons - Notes and Quiz

Questions:
Quizzes and Tests on Chemical Bonding

No comments:

Post a Comment