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Some of the elements in the periodic table are metals - Edexcel - GCSE Chemistry - Question 6 - 2019 - Paper 1
Question 6
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 ta... show full transcript
Worked Solution & Example Answer:Some of the elements in the periodic table are metals - Edexcel - GCSE Chemistry - Question 6 - 2019 - Paper 1
Step 1
Which row shows the group and period of the periodic table where this metal is found?
Answer
The electronic configuration 2.8.3 indicates that the metal is in Group 3 and Period 3 of the periodic table. This is because:
- The first number (2) represents the first shell.
- The second number (8) represents the second shell.
- The third number (3) indicates it has three electrons in its outer shell, placing it in Group 3.
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 will react vigorously, producing hydrogen gas and forming rubidium hydroxide. The reaction is typically characterized by:
- Bubbling or fizzing as hydrogen gas escapes.
- Heat generation, which may cause the rubidium to ignite and burn with a lilac flame.
Step 3
Explain, in terms of their electronic configurations, why lithium is less reactive than potassium.
Answer
Lithium has the electronic configuration of 2.1, while potassium has the configuration of 2.8.8.1. The key reasons why lithium is less reactive are:
- Outer Electron Configuration: Lithium has one electron in its outer shell, while potassium has one more electron (total of 8 in its outer shell before losing one).
- Atomic Size: Potassium has a larger atomic radius compared to lithium, leading to the outer electron being further from the nucleus.
- Shielding Effect: Potassium has more inner electron shells, reducing the effective nuclear charge felt by its outer electron, making it easier for potassium to lose this electron compared to lithium.
Thus, lithium is less reactive because its outer electron is held more tightly due to the greater effective nuclear charge and smaller atomic radius.