Atomic theory 5 Flashcards
Write the electron configuration (s. p etc) for an iron atom.
1s₂ 2s₂ 2p₆ 3s₂ 3p₆
What term is used to refer to the condition of the hydrogen atom when its electron occupies the E1 level?
Ground state
What term is used for the condition of the hydrogen atom when its electron occupies any of the levels E2, E3 etc?
Excited state
What causes the electron to leave the E1 level?
- It acquires energy
- It is heated
Why does the electron not remain in any of the levels E2, E3 etc?
Higher energy states unstable
The visible lines in the atomic emission spectrum of a sample of hydrogen are produced when electrons fall to a particular energy level. Identify this energy level.
E₂ / n = 2
Bohr’s theory considered electrons as tiny particles restricted to orbits. How does modern atomic theory describe the behaviour of electrons?
Electrons have both wave and particle properties.
What are orbitals?
An atomic orbital is a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
Identify the main energy levels involved in the electron transition that gives rise to the first (red) line of the Balmer series in the emission spectrum of the hydrogen atom.
2 and 3
Define an atomic orbital.
An atomic orbital is a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
Write the ground state s, electron configuration for a carbon atom. How many orbitals are occupied?
1s₂ 2s₂ 2p₂
4 orbitals occupied
Distinguish between the ground state and the excited states of the electron in a hydrogen atom.
Ground - n = 1
Excited - n = 2,3
How can the electron in a hydrogen atom become excited?
Add heat
Explain the origin of the series of visible lines in the emission spectrum of hydrogen. What name is given to this series?
- Excited electrons fall back from n = 3,4 to n = 2, the energy lost is emitted as light of different frequencies.
- Balmer series
Explain why there is no yellow line in the hydrogen emission spectrum.
No corresponding excited state
Describe how to carry out a flame test to confirm the presence of lithium in a salt sample.
Clean a platinum (nichrome) wire in concentrated hydrochloric acid
Dip rod in salt and hold salt in hot part of Bunsen flame
Red crimson colour is a positive result for lithium
Define an atomic orbital.
An atomic orbital is a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
Distinguish between a 2p orbital and a 2p sublevel.
2p sublevel consists of three 2p orbitals of equal energy
Write the s, p electron configuration for a calcium atom.
1s₂ 2s₂ 2p₆ 3s₂ 3p₆ 4s₂
Explain in terms of energy sublevels why the arrangement of electrons I the main energy levels in a calcium atoms is 2, 8, 8, 2 and not 2, 8, 10.
- 4s sublevel lower in energy than the 3d
- Electrons fill the 4s sublevel before the 3d
Explain how the line emission spectrum of hydrogen arises and provides evidence for the existence of energy levels.
- In the ground state the hydrogen electron occupies the lowest available energy level.
- The electron can jump to a higher energy level if it recieves a certain amount of energy
- Excited state unstable
Evidence - Energy emitted corresponds to difference between the two energy levels.
Suggest an element that gives a blue-green colour to a fireworks display.
Copper
Write the s, p configuration of a calcium atom in its ground state.
1s₂ 2s₂ 2p₆ 3s₂ 3p₆ 4s₂
Give one significant difference between an electron in the 2s orbital and an electron in the 3s orbital of a calcium atom.
- Energy of 2s electron is less than 3s
State the famous principle published in 1927, which bears the name Werner Heisenberg.
Position and momentum of an electron cannot be found simultaneously.
Name the scientist whose work on energy levels in the hydrogen atom is depicted in the Google doodle reproduced above.
Bohr
Distinguish between the terms energy level and atomic orbital.
Energy level - Is the discrete amount of enegry an electron has when it is in an atom.
An atomic orbital - is a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
Write the electron configuration (s, p) of an atom of silicon showing the distribution of electrons in atomic orbitals in the ground state.
1s₂ 2s₂ 2p₆ 3s₂ 3p₂
Distribution on marking scheme (2014)
State how many (i) main energy levels, (ii) atomic orbitals are occupied in the silicon atom in its ground state.
(i) 3
(ii) 8
Use Bohr’s atomic theory of 1913 to account for the emission spectrum of the hydrogen atom.
- The electron in a hydrogen atom occupies fixed energy levels.
- In the ground state electrons occupy the lowest available energy levels.
- The electron can move to a higher energy level if it receives a certain amount of heat
- Excited state unstable
- Emitting excess energy in the form of a photon of light
Explain in terms of atomic structure, why different flame colours are observed in flame tests using salts of different metals.
Metal atoms of different elements have different sets of energy levels therefore they emit different frequencies.
What colour is observed in a flame test on lithium chloride?
Red
Describe the testing procedure in a flame test on lithium chloride.
- Salt on platinum probe
- Hold in at top of flame
Explain the term uncertainty principle.
This states that it is impossible to know both the position and the speed of an electron at the same time as electrons move in a wave motion.
Give one factor that contributed to the need for modification of Bohr’s 1913 theory other than Heisenberg’s uncertainty principle.
- Wave nature of electron
What is an atomic orbital?
An atomic orbital is a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
Define atomic orbital.
An atomic orbital is a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
Write the electron configuration (s, p etc) of the element manganese (Mn).
1s₂ 2s₂ 2p₆ 3s₂ 3p₆ 4s₂ 3d₅
What do the electron configurations of the series of elements from scandium to zinc have in common?
Electrons entering 3d sublevel / All end in 3d(x)
State the number of (i) sub-levels, (ii) orbitals, occupied by electrons in an argon atom in its ground state.
(i) 5
(ii) 9
Write the electron configuration (s, p) of an oxygen atom showing the arrangement of electrons in atomic orbitals.
1s₂ 2s₂
Arrangements in marking scheme (2012)
Outline Bohr’s atomic theory based on the hydrogen emission spectrum.
- The electron in a hydrogen atom occupies fixed energy levels
- An electron in an energy level does not radiate energy
- Electron occupies lowest energy levels available
- The electron can move to a higher energy level if it receives an amount of energy
- The photon must be exactly equal to the energy difference between the ground state and a higher energy level.
State two limitations of Bohr’s theory that led to its modification.
- Didn’t work for higher elements
- Did not allow for uncertainty
Draw the shape of the p-orbital.
Dumbbell drawn
Draw the shape of the s-orbital.
In notes
State the maximum number of electrons that can be accommodated in a p-orbital.
2
Write the s, p electron configuration for the potassium atom.
1s₂ 2s₂ 2p₆ 3s₂ 3p₆ 4s₁
How many (i) energy sub-levels, (ii) individual orbitals, are occupied by electrons in a potassium atoms
(i) 6 sublevels
(ii) 10 orbitals
Explain why there are electrons in the fourth main energy level of potassium although the third main energy level is incomplete.
4s sublevel lower in energy than 3d
Write the electron configuration (s, p etc.) of the aluminium ion (Al³+)
1s₂ 2s₂ 2p₆
Name the type of spectroscopy, based on absorptions within a particular range of electromagnetic frequencies, and used as a ‘fingerprinting’ technique to identify organic and inorganic compounds.
infra-red / IR
Define energy level.
One of the discrete amounts of energy that an electron has when it is in an atom.
Distinguish between ground state and excited state for the electron in a hydrogen atom.
Ground - in lowest energy state
Excited - higher energy state
Name the series of lines in the visible part of the line spectrum of hydrogen.
Balmer series
Explain how the expression E2 - E1 = hf links the occurrence of the visible lines in the hydrogen spectrum to energy levels in a hydrogen atom.
- E2 - E1 : Energy difference between higher and lower level
- f = frequency of line in spectrum
- h is Plank’s constant
- Energy difference divided by frequency equals a constant.
Define energy level
One of the discrete amounts of energy that an electron has when it is in an atom.
Write the electron configuration (s, p) for the sulphur atom in its ground state, showing the arrangement in atomic orbitals of the highest energy electrons.
1s₂ 2s₂ 2p₆ 3s₂ 3p₄
Arrangement in marking scheme (2007)
State how many (i) energy levels, (ii) orbitals, are occupied in a sulphur atom in its ground state.
(i) 3
(ii) 9
Describe how you would carry out a flame test on a sample of potassium chloride.
n
Why do different elements have unique atomic spectra?
Each element has a different distribution of energy levels giving rise to different electron transitions.
What instrumental technique is based on the fact that each element has a unique atomic spectra?
Atomic absorption spectrometry (AAS)
Define atomic orbital.
An atomic orbital is a region in space around the nucleus of an atom in which there is a high probability of finding an electron
What does Heisenberg’s uncertainty principle say about an electron in an atom?
It is not possible to measure the exact position and energy of an electron in an atom simultaneously.
Write the electron configuration (s, p etc.) of a chromium atom in its ground state.
1s₂ 2s₂ 2p₆ 3s₂ 3p₆ 4s1 3d₅
Name the series of coloured lines in the line emission spectrum of hydrogen corresponding to transitions of electron from higher energy levels to the second (n=2) energy level.
Balmer series
Distinguish between atomic orbital and a sublevel.
Atomic orbital - a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
Sublevel - A group of atomic orbitals within an atom, all of which have the same energy.
Describe how Bohr used line emission spectra to explain the existence of energy levels in atoms.
- electrons in ground state
- fixed energies absorbed
- excited state unstable
- energy difference between levels gives specific frequency of light in spectrum
Why does each element have a unique line emission spectrum?
Each element has a different distribution of energy levels giving rise to different electron transitions.
Name the instrumental technique that can be used to detect heavy metals and to measure their concentrations in a soil or water sample.
Atomic absorption spectrometry (AAS)
Bohr’s atomic theory was later modified. Give one reason why this theory was updated.
Only worked for simple atoms
Define energy level
One of the discrete amounts of energy that an electron has when it is in an atom.
Define atomic orbital
An atomic orbital is a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
Write the electronic configuration (s, p etc.) of nitrogen.
1s₂ 2s₂ 2p₃
Describe how the electrons are arranged in the orbitals of the highest occupied sub-level of a nitrogen atom in its ground state.
One electron in each of the three p orbitals
Write the electronic configuration of a neutral copper atom.
1s₂ 2s₂ 2p₆ 3s₂ 3p₆ 4s1 3d₁₀
Define atomic orbital.
An atomic orbital is a region in space around the nucleus of an atom in which there is a high probability of finding an electron.
What spectroscopic technique is used to detect heavy metals, e.g. lead, in environmental analysis?
atomic absorption spectrometry / AAS
What is the colour of the light associated with the line spectrum of sodium?
yellow / orange
Explain how line emission spectra occur.
- electrons restricted to energy levels
- jump to higher levels
- fall back emitting energy as light
- energy difference between levels gives specific frequency of light in spectrum.
What evidence do line emission spectra provide for the existence of energy levels in atoms?
- only fixed frequencies are emitted
- therefore electrons must be restricted to certain energy values
Why is it possible for line emission spectra to be used to distinguish between different elements?
- different elements have different spectra
Different metals impart different colours to the Bunsen flame. In case of any two named metals, state the colour imparted.
Sodium - amber/yellow
Potassium - lilac
Explain briefly why different metals produce different flame colours.
Metal atoms of different elements have different sets of energy levels therefore they emit different frequencies.
Write the electronic configuration of the Al³+ ion. What neutral atom has the same configuration?
1s₂ 2s₂ 2p₆
Use diagrams to distinguish between a p orbital and a p sub-level (p subshell).
You have to draw a normal p (infinity sign) and then the different variations of sublevel, when on the x,y and z axes.
Write the electron configuration for nickel in its ground state.
1s₂ 2s₂ 2p₆ 3s₂ 3p₆
State one piece of evidence that supports the existence of atomic energy levels.
The atomic emission spectrum.
