This circuit is used in a school laboratory to show that atoms can form ions. A low-pressure neon tube is connected to a power supply. When the potential di...
Question 1 Report
This circuit is used in a school laboratory to show that atoms can form ions. A low-pressure neon tube is connected to a power supply. When the potential difference is increased, electrons gain energy and some leave neon atoms. The glowing gas then contains positive ions and free electrons. Fig. 1 shows one neon atom before an electron is removed. The diagram is a simple model and does not show the actual path of the electron through the air in the tube.
(a) What is the charge on a neon ion after one electron has been removed? [1]
(b) Calculate the number of electrons in this ion. [1]
(c) Which change happens to the number of protons when the atom becomes an ion? [1]
(d) Describe how the electrical current in the tube is carried. [2]
Answer Details
(a) Removing one negative electron leaves the neon particle with one more proton than electron. Its charge is \(+1\). [1]
(b) A neutral neon atom has 10 electrons. After one is removed:
\[10-1=9\]
The ion has 9 electrons. [1]
(c) The number of protons has no change; it remains 10. Ion formation involves electron transfer, not a change to the nucleus. [1]
(d) The current is carried by free electrons moving through the gas and by positive ions moving. In general, electrical current is the movement of charged particles. [2]
Download The App On Google Playstore
Everything you need to excel in your exams
