Lesson 5, Topic 5
In Progress

# Arrangement of Particles in an Atom

Lesson Progress
0% Complete

In 1913, a scientist Niel’s Bohr forwarded his own model of the atom based on the quantum mechanics originally developed by Planck.

He proposed that the model of an atom consists of an extranuclear part known as an electron which is located in spherical orbits (shell) around the nucleus. The orbit/energy level is designated by Letters ( K, L, M, N). These labels correspond to the principal quantum numbers 1, 2, 3, 4… respectively.

### Energy Levels and Maximum number of Electrons

Hydrogen, $$\scriptsize _{1} ^{1} \textrm {H}$$

Helium, $$\scriptsize _{2} ^{4} \textrm {He}$$

Carbon, $$\scriptsize _{6} ^{12} \textrm {C}$$

Sodium, $$\scriptsize _{11} ^{23} \textrm {C}$$

### Electronic configuration of the 1st 20 Elements

K, L, M, N = Shell Electronic Configuration

Theory Questions

1. (a) Give two reasons to show that matter exists in form of particles

(b). Define the following, giving two examples in each case
(i)Atom (ii) Molecule (iii) Ion

2. What are the contributions of the following scientists in the constituents of the atom (i) J.J Thompson (ii) Robert Millikan (iii) Ernest Rutherford (iv) James Chadwick (v) Henry Mosely (vi) Neil Bohr.

3. (a) Name the three particles of an atom, their charges, mass and their position in the atom (b) Draw a simple model of an atom

error: