E

Question 1

Bohr experiment

Answer 1

Carried out experiment in hydrogen discharge tube.
He seen a series of lines called emission line spectrum.
The fact the spectrum consisted of a series of lines showed that only certain energy emissions are possible.

Question 2

Bohr concluded

Answer 2

1.In atom, electrons revolve around nucleus at certain allowed orbits or shells.when in shell electron has definite amount of energy
2.Energy level= the discrete amounts of energy an electron has in the atom.when close to nucleus it has little energy,when far from it has more energy
3.when electron stay in particular amounts of energy level its energy remains the same.
4.when atom absorb energy,electon jump from lower to higher energy levels.excited state- unstable- temporary
5.excited electron will fall back down to a lower energy level. As it does energy is given off.- electron can only fall back to certain energy,only fixed amounts of energy can be given off.

Question 3

Atomic emission spectrum of hydrogen(atoms of hydrogen giving off energy)

Answer 3

1.Hydrogens only electron occupies lowest energy level available->ground state
2.When energy is given.eg. Heated ->electron is promoted to higher energy level.- state unstable and temporary
3.When ē falls down to lower EL the difference is emitted as photon of light-E2-E1=E
4.Each line in spectrum is result of electron moving from one energy level into a lower one
5.Each transition has a definite energy and and shows as a line of particular colour in the line emission spectrum-each line has a definite frequency.-limited amounts of energy changes are possible within the structure of an atom.

Question 4

When electron jumps from higher EL to the

Answer 4

N1=Lyman series-exists in ultra violet band
N2=Balmer series -visible bacl
N3=Paschen series-infra red band

Question 5

Why do different elements have unique atomic spectra?

Answer 5

Each element has a different arrangement of energy levels and electronic configuration, giving different electron transitions from higher to lower energy levels.

Question 6

Explain why different metals produce different flame colours

Answer 6

Diff metals have diff amount of electrons, therefore arrangement of electrons
Diff ē transitions occur from one EL to another
Each transition has a definite amount of energy thus frequency thus wavelength

Question 7

Atomic absorption spectrum AAS

Answer 7

Atoms can absorb light.
If white light is passed through an element in its gaseous form the light comes out as missing wavelengths.
Appear as dark lines and has same energy emission spectrum
The amount of light absorbed is proportional to the concentration of the element
Therefore, atoms in the ground state can absorb the same amount of energy as they would emit in the excited state

Question 8

Limitations of Bohr’s theory

Answer 8

Theory failed when applied to atoms with more than one electron
Does not allow for uncertainty
Does not explain the discovery of sub levels

Question 9

Heisenberg’s uncertainty principle1927

Answer 9

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 of motion

Question 10

Atomic orbital

Answer 10

Region of space around the nucleus of an atom where there is a higher probability of finding an electron

Question 11

Energy level

Answer 11

The exact amount of energy and electron has when it is in an atom

Question 12

Energy sub level

Answer 12

Group of atomic orbitals within an atom ,all of which have the same energy