The diagram shows particles in a concentrated saline solution used to preserve a laboratory electrode. Sodium atoms have atomic number 11. One sodium atom h...
Question 1 Report
The diagram shows particles in a concentrated saline solution used to preserve a laboratory electrode. Sodium atoms have atomic number 11. One sodium atom has transferred an electron to form a sodium ion, while chloride ions are also present. Table 1 records the particle numbers for two species in the solution.
| species | number of protons | number of electrons |
|---|---|---|
| sodium atom | 11 | 11 |
| sodium ion | 11 | 10 |
| chloride ion | 17 | 18 |
(a) Give the charge on the sodium ion in Fig. 1. [1]
(b) Use Table 1 to explain how a sodium atom becomes a sodium ion. [2]
(c) Complete the electronic configuration of the sodium ion: 2, ________. [1]
(d) Name the particle that sodium and chloride ions both contain. [1]
(e) State why the saline solution can conduct electricity when it contains these ions. [2]
Answer Details
(a) The sodium ion has charge 1+. [1]
(b) A sodium atom loses one electron. It then has 11 protons but only 10 electrons, so there is one more positive charge than negative charge and the particle is Na+. [2]
(c) The sodium ion has electronic configuration 2,8. [1]
(d) Sodium and chloride ions both contain protons. Electrons would also be accepted, since both ions contain electrons. [1]
(e) Saline solution conducts because the ions are charged particles and are free to move through the solution, carrying electrical charge. [2]
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