Chemistry
Atomic structure and bonding — Topics 2-3
- 1.
Chlorine contains 75% chlorine-35 and 25% chlorine-37. Calculate its relative atomic mass.
[4 marks] - 2.
Explain why sodium chloride conducts electricity when molten but not when solid.
[4 marks] · no calculator - 3.
An atom of aluminium has atomic number 13 and mass number 27. State the number of protons, neutrons and electrons it contains.
[3 marks] · no calculator - 4.
Draw (in words) and describe the electronic structure of a chlorine atom (atomic number 17), stating the number of electrons in each shell.
[3 marks] · no calculator - 5.
Explain, in terms of electron transfer, how an ionic bond forms between a sodium atom and a chlorine atom to form sodium chloride.
[4 marks] · no calculator - 6.
Explain, in terms of shared electron pairs, how a covalent bond forms between two chlorine atoms in a Cl₂ molecule.
[3 marks] · no calculator - 7.
Explain why giant covalent structures, such as diamond, have very high melting points.
[3 marks] · no calculator - 8.
Explain why simple molecular substances, such as iodine, have low melting and boiling points compared to giant ionic or covalent structures.
[3 marks] · no calculator - 9.
Explain why metals are good conductors of electricity, in terms of their bonding and structure.
[3 marks] · no calculator - 10.
An atom loses two electrons to form a 2+ ion. State how the number of protons, neutrons and electrons changes, if at all, when this happens.
[3 marks] · no calculator - 11.
An atom of oxygen has atomic number 8. State its electronic structure, and state which group of the periodic table it belongs to, explaining your reasoning.
[3 marks] · no calculator - 12.
Explain, in terms of electron transfer, how an ionic bond forms between a magnesium atom and an oxygen atom to form magnesium oxide.
[4 marks] · no calculator - 13.
Explain, in terms of electron transfer, how calcium chloride, CaCl₂, forms from calcium and chlorine atoms, accounting for the 1:2 ratio of calcium to chlorine in the formula.
[4 marks] · no calculator - 14.
Describe, using shared electron pairs, the covalent bonding in a molecule of water, H₂O, stating the number of shared pairs and the number of lone (non-bonding) pairs on the oxygen atom.
[3 marks] · no calculator - 15.
Sodium chloride forms a giant ionic lattice structure. Describe this structure, and explain why ionic compounds generally have high melting points.
[3 marks] · no calculator - 16.
Explain why ionic compounds are typically hard but brittle, in terms of their lattice structure.
[3 marks] · no calculator - 17.
Describe the structure of graphite, and explain why it is used as a lubricant and as an electrode, despite being an allotrope of carbon like diamond.
[4 marks] · no calculator - 18.
Describe the structure of diamond, and explain why it is extremely hard and does not conduct electricity.
[3 marks] · no calculator - 19.
Explain how the position of an element in the periodic table relates to its electronic structure, using magnesium (Period 3, Group 2) as an example.
[3 marks] · no calculator - 20.
State the difference between mass number and relative atomic mass, and explain why the relative atomic mass of chlorine (35.5) is not a whole number.
[3 marks] · no calculator - 21.
Copper consists of 69% copper-63 and 31% copper-65. Calculate the relative atomic mass of copper.
[3 marks] - 22.
State three general physical properties of ionic compounds.
[3 marks] · no calculator - 23.
State three general physical properties of simple molecular (covalent) compounds.
[3 marks] · no calculator - 24.
Explain, in terms of structure and bonding, why metals are malleable (can be hammered into shape) without shattering.
[3 marks] · no calculator - 25.
Explain why alloys, such as brass (a mixture of copper and zinc), are generally harder than the pure metals from which they are made.
[3 marks] · no calculator