Photo AI
Some of the elements in the periodic table are metals: (a) The electronic configuration of a metal is 2.8.3 - Edexcel - GCSE Chemistry Combined Science - Question 4 - 2019 - Paper 1
Question 4
Some of the elements in the periodic table are metals: (a) The electronic configuration of a metal is 2.8.3. Which row shows the group and period of the periodic t... show full transcript
Worked Solution & Example Answer:Some of the elements in the periodic table are metals: (a) The electronic configuration of a metal is 2.8.3 - Edexcel - GCSE Chemistry Combined Science - Question 4 - 2019 - Paper 1
Step 1
Step 2
Describe what you would see when a small piece of rubidium is dropped on to water.
Answer
When a small piece of rubidium is dropped into water, it would react vigorously, producing heat and a potential fire hazard. You would see fizzing as hydrogen gas is released, and the rubidium may dissolve or float, possibly catching fire.
Step 3
Explain, in terms of their electronic configurations, why lithium is less reactive than potassium.
Answer
Lithium's electronic configuration is 2.1, meaning it has only one electron in its outer shell, while potassium's configuration is 2.8.8.1, with one electron in its outer shell as well. However, potassium's outer electron is further from the nucleus due to its larger size (more electron shells). This results in less attraction between the outer electron and the nucleus in potassium compared to lithium, making potassium more reactive.
Step 4
Calculate the relative atomic mass of lithium in this sample. Give your answer to two decimal places.
Answer
To calculate the relative atomic mass of lithium:
-
For lithium-6:
\[ 7.59 ext{ (percentage)} imes 6 ext{ (mass)} = 45.54 ]
-
For lithium-7:
\[ 92.41 ext{ (percentage)} imes 7 ext{ (mass)} = 646.87 ]
-
Add the results:
\[ 45.54 + 646.87 = 692.41 ]
-
Divide by 100 to find the average:
\[ 692.41 / 100 = 6.92 ]
Thus, the relative atomic mass of lithium in this sample is 6.92.