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16 Lithium is a metal found in Group 1 of the Periodic Table - OCR Gateway - GCSE Chemistry - Question 16 - 2019 - Paper 3
Question 16
16 Lithium is a metal found in Group 1 of the Periodic Table. (a) (i) Describe the structure and bonding in a metal. You may include a diagram in your answer. ___... show full transcript
Worked Solution & Example Answer:16 Lithium is a metal found in Group 1 of the Periodic Table - OCR Gateway - GCSE Chemistry - Question 16 - 2019 - Paper 3
Step 1
Describe the structure and bonding in a metal.
Answer
Metals have a metallic structure which is characterized by a regular arrangement of positively charged metal ions surrounded by a sea of delocalized electrons. This structure allows metals to conduct electricity and heat efficiently. The metal ions vibrate around fixed positions, and the delocalized electrons move freely throughout the structure. Below is a simple diagram illustrating the metallic lattice arrangement:
+ + +
+ + + +
+ + + +
+ + +
In this diagram, the plus signs represent metal cations, while the empty spaces represent the delocalized electrons.
Step 2
Explain why metals are malleable.
Answer
Metals are malleable because the layers of ions in a metallic lattice can slide over one another without breaking the metallic bonds. When force is applied, the delocalized electrons can adjust their positions, allowing the structure to deform rather than fracture. This property allows metals to be shaped into various forms without losing their integrity.
Step 3
Explain why metals can conduct electricity.
Answer
Metals can conduct electricity due to the presence of delocalized electrons that are free to move throughout the metallic structure. When an electric field is applied, these electrons can flow in response, allowing the metal to conduct electric current efficiently. This property is consistent whether the metal is in solid or liquid form.
Step 4
Is she correct?
Answer
To determine if alloy C is best for making an aircraft, we must analyze the properties presented in the table. Alloy C has a strength of 565 MPa, which is higher than both alloy A (550 MPa) and alloy B (555 MPa). However, the density of alloy C (2.55 g/cm³) is lower than alloy A (2.58 g/cm³) and slightly less than alloy B (2.56 g/cm³). A lower density may suggest that alloy C is lighter, which is beneficial for aircraft. Therefore, while alloy C has the highest strength and favorable density, it can be concluded that the scientist is correct in suggesting alloy C might be suitable for aircraft applications due to its strength and moderate density.
Step 5
Calculate the percentage of lithium atoms in the diagram of alloy B.
Answer
To calculate the percentage of lithium atoms in alloy B, first count the total number of atoms in the diagram. Then, count the number of lithium atoms present. The percentage can be calculated using the formula:
If, for example, there are 3 lithium atoms in a total of 10, the calculation would be: