Bohr's Theory

Question 1

Who proposed the existence of energy levels/ shells/ orbits

Answer 1

Bohr

Question 2

define energy level

Answer 2

the fixted amount of energy an electron in an atom has

Question 3

why cannot electrons occupy spaces between energy levels

Answer 3

it is unstable and will fall to a lower energy level

Question 4

ground state

Answer 4

when all the electrons in an energy level occupy the lowesy avliable energy levels, most stable state for an electron

Question 5

excited state

Answer 5

when electrons have absorbed enough energy to jump/ promoted to higher energy levels- unstable state, electrons will drop back down to lover levels

Question 6

what is the evidence for the existance of energy levels in atoms

Answer 6

line emission spectrum for hydrogen

Question 7

give two ways electrons in an atom can be excited

Answer 7

heating the element
passing an electric current though the element

Question 8

what is a line emission spectrum

Answer 8

a series of coloured lines that correspond to specific frequencies of light emitted when when electrons in an element are excited

Question 9

Explain how the visible line emission spectrum of hydrogenarises and provised evidence for the existence of energy levels

Answer 9

-In the ground state of hydrogen atoms, its electrons occupy the lowest energy level, N=1
-if electrons absorb sufficent energy, they are promoted/ jump up to higher energy levels.
-electrons in the excited state are tempoary and they are unstable and fall back dowb to lower energy levels a short amount of time.
-A definite frequency photon of frequency is emitted depending of electron transition.
-electrons that transition back to n=2 produce a frequency that gives visible coloured light.
This relationship can be demostrated by.
E2-E1 = hf (f= photon)

Question 10

what name is given to the series of visible coloured lines produced in a hydogen emission spectrum, caused by electrons falling from higher energy levels to n=2

Answer 10

Balmer series

Question 11

explain why there is no yellow line in the hydrogen emission spectrum.

Answer 11

There is no corresponding electron transition in hydrogen that would produce light frequency that gives a yellow colour.

Question 13

Describe the flame test

Answer 13

Fume cupboard
Concentrated Hydrochloric acid
Platinum wire
If wire is clean there should be no colour produced
Crush salt with Pestle and mortar
Identify the metal from the salt

Question 14

Why do different metals produce different flame colours

Answer 14

Each element has a different electron configuration
Therefore different electron transitions are possible
So different frequencies of light will be emitted from each element

Question 15

Lithium Chloride produces the colour

Answer 15

Crimson Red

Question 16

Potassium Chloride produces the colour

Answer 16

Lilac

Question 17

Barium Chloride produces the colour

Answer 17

Green

Question 18

Strontium Chloride produces the colour

Answer 18

Dark red

Question 19

Copper Chloride produces the colour

Answer 19

Blue/green

Question 20

Sodium Chloride produces the colour

Answer 20

Yellow

Question 21

What are flame tests

Answer 21

heating an elemnt in a busen burner will cause that element to produce a charateristic colour. The element can therefor be identified

Question 22

Give two reasons why different elements have different atomic emission spectra/impart
different colours to a bunsen flame

Answer 22

Different metals have different transitions between their energy levels
Different metals have different numbers of electrons…
meaning specific freauencies of light are emitted for each specific element

Question 23

What does AAS stand for

Answer 23

Atomic absorbtion spectrometry

Question 24

What is AAS

Answer 24

When white light is passed through a gaseous sample of an element, certain wavelengths were missing.
These lines correspond excatly to the lines produced in produced in the emission line spectrum

Question 25

Name uses for mass specrometry

Answer 25

identifying dangerous element in water (presence of hard metals)
identifyong elements present in stars.

Question 26

Name applications for the use of knowledg of energy levels in everyday life

Answer 26

atomic absorbtion spectrometry (AAS) - identify dangerous elements in water
fireworks

Question 27

Descibe limitations of Bohrs theory

Answer 27

1. He didn’t take into account wave particle duality
   2.The excact position and velocity of an electron could not be measured at the same time so they cannot discribes as ravelling in fixed paths- Heisenberg’s uncertainty principle
2. Didn’t take into account sub levels

Question 28

what is a sub level

Answer 28

subdivision of a main energy that consists of one or more atomic orbitals of equal energy

Question 29

what is heisenberg’s uncertainty principle

Answer 29

it impossible to measue simultaneously both the exact position and velocity of an electron

Question 30

what is an atomic orbital

Answer 30

region in space around the nucleus of an atom where there is high probality of finding an electron

Question 31

List energy sub level from1-4

Answer 31

4f
4d
4p
3d
4s
3p
3s
2p
2s
1s

Question 32

Who devised a equation to work out the probiotic of finding an electron in a particular sublevel

Answer 32

Erwin Schrödinger

Question 33

Describe a S sub level

Answer 33

Spherical and each contain 1 orbital

Question 34

Describe a P sub level

Answer 34

Dumbbell shaped
Conduits of three orbitals (Px ,Py, Pz)

Question 35

Describe D sub level

Answer 35

They contain 5 orbitals

Question 36

How many electrons does each orbital hold

Answer 36

2

Question 37

What is wave particle dualitiy

Answer 37

All moving electrons actually move in a wave motion

Question 38

give two differences between an atomic orbit, as describes by bohr, and an atomic orbital

Answer 38

Orbit - electrons travel in fixed paths in a definite location
-has a max capacity of 2n2(squared) electrons

Orbital region of space where there is a high probability of finding an electron
has a max capacity of 2 electrons

Question 39

Distinguish between a 2p orbital and a 2p sublevel

Answer 39

2p orbital has a max capacity of 2 electrons
2p sublevel has a max capacity of 6 electrons, consists of three 2p orbitals