This page contains the AQA AS Chemistry C1 Atomic Structure Questions and kerboodle answers for revision and understanding Atomic Structure.This page also contains the link to the notes and video for the revision of this topic.
Ans- a) protons,neutrons
b) protons,neutrons
c) protons,electrons
d) neutrons
e) electrons
Ans- We assume this that there are same number of protons and electrons in an atom because the net charge on an atom is 0 and electrons and protons carry equal and opposite charge.
Banner 21. Isotopes are usually identified by the name of the element and the mass number of the isotopes,as in carbon-13.However,isotopes of hydrogen have their own names.Hydrogen-2 is often called deutrium and hydrogen-3 tritium.However, both these isotopes behave chemically just like the most common isotope,hydrogen-1.State how many protons,neutrons and electrons the atoms of the following have:
a)deutrium
b)tritium
Ans- a) 1 proton,1 neutron,1 electron
b)1 proton,2 neutron,1 electron
2. 31W15 , 14X7 , 16Y8 , 15Z7 Identify which of these atoms(not their real symbols) is a pair of isotopes.
Ans- W-Phosphorus, X-Nitrogen, Y-Oxygen, Z-Nitrogen.
3. For each element in question 2, state
a)the number of protons
b)the mass number
c)the number of neutrons
Ans-
a)the number of protons:-
31W15 -15
14X7 – 7
16Y8 -8
15Z7 -7
b)the mass number-
31W15 -31
14X7 – 14
16Y8 -16
15Z7 -15
c)the number of neutrons-
31W15 -16
14X7 – 7
16Y8 -8
15Z7 -8
Banner 3
Ans- a) 2,2
b)2,8,3
c)2,8,8
|
A. B. C. D. E. | Number of protons 12 2 17 10 3 | Number of electrons 10 2 18 10 2 |
|
| ||
Ans- A-Mg2+
B-He
C-Cl–
D-Ne
E-Li +
Banner 4Ans-The ions formed in a mass spectrometer are positively charged because they are formed either by gaining a proton from the solvent(electrospray ionisation) or either by removal of electron(electron impact).
Ans-The ions accelerate through the mass spectrometer because they are positively charged and the charge on the plate is negative therefore the ions are attracted towards it hence they accelerate.
Ans-When the ions pass through the hole in negatively charged plated they get converted into a beam.
1. State which ions will arrive at the detector first.
Ans-The ions which have greater charge and lighter mass arrive first at the detector.
2. Use the information about germanium in Fig to calculate out its relative atomic mass.
Ans- (70 X 20.5)+(72 X 27.4) +( 73 X 7.8) + (74 X 36.5) + (75 X 7.8)
_____________________________________________________=72.632
100
3. Figure shows the mass spectrum of copper.Calculate the relative atomic mass of copper.
(63 X 70)+(65 X 30)
________________=63.6
100
Banner 5Ans- a) 2,8,5
b) 1s22s22p63s23p3
Ans- a) (i) 2,8,8 (ii) 2,8
b)(i) 1s 22s 22p 63s 23p 6 (ii) 1s22s22p6
Baneer 6
1. Write an equation to show the process that occurs when the first ionisation energy of aluminium is measured.
Ans- Al->Al+ + e–
2. State which of the first,second or third ionisation of aluminium would produce an ion with the electronic configuration 1s2,2s2,2p6,3s1.
Ans- first and second IE.
3. Explain why the value of the first ionisation energy of sulfur is less than the value of the first ionisation energy of phosphorus.
Ans-This is due to the inter-electronic repulsion between the paired electrons of Sulfur in 3p orbitals.This repulsion makes it easier to remove the electrons hence it becomes easier to remove one of them. Thus it has IE of sulfur is less than that of Phosphorus.
4. Identify the element in Period 2 that has the highest first ionisation energy and give its electronic configuration.
Ans- Neon 1s22s22p6
5. State the trend in the first ionisation energies in Group 2 from beryllium to barium.Explain your answer in terms of a suitable model of atomic structure.
Ans-Be>Mg>Ca>Sr>Ba
This is because down the group size increases and the nuclear force on outer electrons decreases.
B).
Ans- (i) Isotopes are atoms that have the same number of protons and electrons but different numbers of neutrons and have same chemical properties.
(ii) Isotopes have same chemical properties because the number of electrons are same in all isotopes.
Ans- 1s22s22p63s1.
Ans- no of protons-14/2=7
No of neutrons- 8
Mass num=15. Atomic num=7. The symbol is N.
Ans-The energy required to remove first electron from a neutral atom is called as first ionisation energy.
Ans- Mg+->Mg2+ +e–
Ans- The first IE of Mg is higher than that of Na as the nuclear charge of Mg is greater than Na hence the electron experience greater force.
Ans-
(i) Isotopes are atoms that have the same number of protons and electrons but different numbers of neutrons and have same chemical properties.
(ii) The positive ions on reaching the detector pick up and electron from the detector which causes a current to flow.This is how the ions are detected. The flight time is recorded,which differs on the basis of charge/mass and the data is used to generate the mass spectrum which measures the abundance.
Ans- Relative atomic mass of an element is the ratio of its average mass of 1 atom to (1/12)th mass of 1 atom of 12C.In this scale the mass of a carbon atom is taken to be exact 12.
Use the data above to calculate the relative atomic mass of iron in this sample.Give the answer to the appropriate number of significant figures.
Ans- (54 X 5.80)+(56 X 91.60)+(57 X 2.60)
_________________________________=55.91
100
E).
Ans-Positive ions are formed either by absorbing protons from the solvent in electrospray ionisation method or by removal of 1 electron in electron impact method.
Ans- The apparatus is kept under high vacuum to prevent the colliding of ions with the air molecules.
Ans-The ions are accelerated by high voltage and also due the attractive force experienced due to the negatively charged plate. They are separated by the mass in the instrument because the flight time is recorded and the ions accelerate depending upon their charge/mass ratio i.e Lighter the ion greater the acceleration which results in lesser flight time.
Ans- The ions on reaching the detector picks up an electron.This flow of charges produce an electric current.
Ans- (i)
| Mass/Charge 24 25 26 | Number of protons 12 12 12 | Number of neutrons 12 13 14 |
(ii) (24 X 79)+(25 X 10)+(26 X 11)
________________________=24.32
100
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