Arrangement Of Electrons In Atoms Flashcards
What is the plum pudding model?
There are negative electrons embedded in a sphere of positive charge.
What model was accepted 1898 to show electrons in the atom?
Thomson’s plum pudding model.
What did Rutherford’s experiments show?
The atom had lots of space in which electrons orbited a dense, small nucleus.
What did Bohr use to show that the atom had electron shells?
The line/emission spectrum.
When a gas is heated/electricity is passed through it, light is given off. This light can be passed through a prism and the light splits and forms a spectrum.
How did Bohr prove there were electron shells?
When electrons gain energy they become excited (raised to a higher energy level). As they fall back to their original level, light is emitted.
Why do atoms emit light that forms a line spectrum?
Light carries energy which relates to the frequency of the light.
Excited atoms emit light as they’ve gained energy.
Electrons traveling through the discharge tube collide with the atoms and transfer energy which they lose by emitting light.
What does the limited number of frequencies of light tell you?
Only a limited number of energy changes/transitions can take place within the atom.
What does quantum mechanics say?
Electrons in atoms are arranged in a series of shells.
Each shell may contain a number of subshells.
How are the shells labelled?
With the principal quantum number, n=(number).
The larger the number the further from the nucleus the electron is likely to be.
What is ionisation?
The complete removal of an electron form an atom.
What type of process is ionisation? Why?
An endothermic process as work must be done to overcome the attractive force between it and the nucleus.
What is the amount of energy needed to remove the electron called?
The ionisation energy.
How is ionisation energy measured?
Gradually increasing voltage applied to GAS until it conducts electricity & emits light.
This tells you an electron has been freed.
What is an atom in its ground state?
At its lowest energy level.
What is the energy to remove the first, second etc. electrons called?
The first/second/etc. ionisation energy.
