AQA AS Chemistry C8 Periodicity Kerboodle Answers

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8.1 The Periodic Table AQA AS Chemistry C8 Periodicity Kerboodle Answer: Page No.142

1.Ans-

1. i)K,Br (ii) Br,Cl  (iii) Br,Cl
2. i) Fe (ii) K

2.Ans-

1. Xe
2. Ti
3. Sr
4. Xe
5. Ti

3.Ans-

1. Left,middle
2. Right

 8.2 Trend The Properties Of Elements AQA AS Chemistry C8 Periodicity Kerboodle Answer: Page No.145

4.Ans-

1. Group 18
2. Group 14

5.Ans- B can be covalent molecules with giant structures or macromolecules whereas A is a metal.This is because since A is good conductor of electricity this means it has free electrons. 6.Ans- The size of the atoms increases as the nuclear charge increases. 7.Ans- Ionisation energy increases as nuclear charge increases. 8.Ans- The nuclear charge increases on moving from left to right. 9.Ans- Noble gas has highest ionization energy because they have a very stable electronic configuration as their outer shell is completely filled. Ans-   a) 1s²,2s²         b) 1s² 2s² 2p¹ 10. Ans- a) 2         b) 2 11.Ans- This is because its valence electron (2p1) of Boron is shielded by the 2s electrons, less energy is required to remove the the 2p electron(s) from a boron atom than is requried to remove the 2s electron from a beryllium atom.  

Practice Questions-

1.Ans-

1. Silicon has a giant covalent structure.
2. Both sulfur and phosphorus are simple molecules with covalent bonding though sulfur molecules are larger.The melting point of sulfur is higher than that of phosphorus because the van der waals forces are stronger in case of sulfur so more energy is required.
3. Aluminium is malleable, and ductile due to its polycrystalline structure and when force is applied to it the atoms roll over each other they just move from one lattice site to another.
4. The melting point of aluminium is higher than that of sodium because the metallic bonding is stronger in case of aluminium in comparison to sodium due to greater nuclear charge and smaller size.

2.Ans-

1. Lithium has the largest atomic radius
2. i) The ionization energy increases on moving from left to right in a period i.e from going to lithium it increases.
3. ii) Boron deviates from the general trend.This is because its valence electron (2p1) of Boron is shielded by the 2s electrons, less energy is required to remove the the 2p electron(s) from a boron atom than is requried to remove the 2s electron from a beryllium atom.
4. Carbon

Src-http://i.imgur.com/A3Hjyz0.jpg

1. Melting point of carbon is high as it has very strong covalent bonds holding the atoms together in a long chain or giant structures.

3.Ans-

1. i)

Src-http://i.imgur.com/7ZQUeO3.jpg

1. ii) 1s²,2s²,2p⁶,3s¹

iii)Al⁺ -> Al⁺² + e^–

1. iv) Second ionization energy of silicon is lower than the second ionization energy of aluminium because the second electron of silicon is a 3p¹ electron while that of aluminium is 3s² electron and 3p has a lower binding energy than that of 3s electron.
2. Sodium because after losing one electron it attains noble gas configuration and is highly stable.
3. Silicon
4. The ionization energy of every element is endothermic because electron is to be removed from the atom against the nuclear force of attraction hence energy is absorbed by the atom.

4.Ans-

1. From carbon to fluorine carbon has largest atomic size because it has least nuclear charge.
2. Generally ionization energy of elements increases across the period from left to right.
3. Oxygen deviates from this trend.It has a ionisation energy lower than that of oxygen has nitrogen has a half filled electronic configuration 1s²,2s²,3p³which is more stale than an incomplete p-orbital if oxygen.
4. Second ionisation energy of carbon is higher than the first ionisation energy of carbon because after removal of the first electron the number of protons increases in comparison to number of electrons hence a greater electrostatic pull is experienced by the electrons.
5. Lithium has highest second ionisation energy since after the removal of one electron it attains a noble gas configuration.

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