Arrangement of Electrons in the Atom,Model Questions and Solutions Flashcards
What term is used to refer to the condition of the hydrogen atom when its
electron occupies the E 1 level?
Ground state
What term is used to refer to the condition of the hydrogen atom when its
electron occupies levels E 2 or higher?
Excited state
What causes an electron to leave the E 1 level?
Energy increase e.g. light or
electricity.
Why do electrons not remain long in the levels E 2 or higher?
The excited
electrons are too unstable.
- Identify the energy level that produces the visible lines in the atomic emission
spectrum.
n=2
- How does the modern atomic theory describe the behaviour of electrons?
Electrons move in a wave particle duality.
- Define an atomic orbital
A region in space about the nucleus where there is a high probability of finding an
electron.
- Write the electron configuration for an iron atom
Fe: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6
- Why is it difficult to specify the absolute boundary of an atom?
Heisenbergs uncertainty principle – we can never be sure of the precise location of an electron when it is moving.
- How many orbitals in a carbon atom?
C 1s2 2s2 2p x 1 2p y 1 - four orbitals in carbon.
- Distinguish between a 2p orbital and a 2p sub level
The 2p sub level is made up of 3 orbitals of equal energy
- Why is the main energy levels a calcium atom 2, 8, 8, 2 and not 2, 8, 10?
The 4s sub level is lover in energy than 3d therefore electrons fill the 4s sub level first.
- Give a significant difference between an electron in the 2s orbital and an electron in the 3s orbital
The size. The 3s orbital is bigger than the 2s orbital.
- State the number of sub-levels and orbitals occupied in an argon atom at
ground state.
Ar 1s2 2s2 2px2 2py2 2pz2 3s2 3px2 3py2 3pz2
Five sub-levels and nine orbitals
- Write the electron configuration of an oxide ion,
O2- O 2- [1s 2 2s 2 2p 6 ] 2-
- State the Pauli exclusion principle
No more than two electrons may occupy an orbital and they must have opposite spin.
- Explain why there are electrons in the fourth main energy level in potassium
even though its third main energy level is incomplete
The 4s sub level is lower in energy than the 3d sub level
- State the maximum number of electrons that can be accommodated in a p-
orbital
Two electrons max per orbital (Pauli exclusion principle)
21.Give another factor, other than Heisenberg that lead to the modification of Bohr’s
theory.
De Broglies wave particle duality.
20.Heisenbergs research lead to the Heisenberg uncertainty principle (1927), which
led to significant modifications of Bohr’s theory. State the Heisenberg
uncertainty theory.
An electron’s position cannot be determined and its velocity known at the same time.
- State Hunds rule of multiplicity
When two or more orbitals of equal energy are available, the electrons occupy them
singly before filling them in pairs.
23.Outline Bohr’s atomic theory based on the hydrogen emission spectrum
An electron in hydrogen occupies fixed energy levels. The electron is in its ground state
and when supplied with energy moves up an energy level and is now in an excited
state. It is unstable and falls back to its ground state producing a photon of light.
E 2 - E 1 = hf
24.Define energy level
The fixed energy value that an electron in an atom may have.
25.Name the visible series
(n = 2) of the line emission spectrum Balmer
series
