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Periodic Properties BOARD Questions 1) What is the atomic radius of an atom? 2) What is the trend in atomic radius across a period? 3) The trend in atomic radius across a period is caused by _____. 4) What generally happens to atomic radii as one goes down a group or a family? 5) Write the equation for the ionization of an atom. 6) What is an ion? 7) What is ionization energy? 8) Which group or family has the lowest ionization energy? 9) Group 18 or 8A, the noble gases, have the highest ionization energy (True or False). 10) Elements with a high ionization energy lose electrons easily (True or False). 11) The increase in ionization energy across a period is caused by _____. 12) Why does ionization energy generally decrease going down a group or family? 13) What is meant by electron shielding? 14) What is the second ionization energy of an atom? 15) What is electron affinity? 16) Write the equation for electron affinity

The first direct experimental evidence for the electrical nature of matter came from the experiments of  Michale Faraday . He showed from his experiments that electricity is composed of particles called ‘atoms of electricity’. It was  George Johnstone Stoney , an Irish Physicist who first proposed the word ‘ electron ‘ for atom of electricity’ in 1891.His contribution to research in this area laid the foundations for the eventual discovery of particles by  J.J. Thomson in 1897. In 1878, Sir William Crooke,  while conducting an experiment using a  discharge  tube, found certain visible rays travelling between two metal electrodes. These rays are known as Crooke’s Rays or  cathode rays . The  discharge  tube used in the experiment is now referred to as Crookes tube or more popularly as Cathode Ray  Tube (CRT). Cathode Ray Tube :  It is a long glass tube filled with gas and sealed at both the ends. It consist of two metal plates (which act as electrodes) connected with hi

Q1 What is meant by electric current? Ans-Electric Current : Flow of electrons. Q2 What is an electrc circuit? Ans -Electric Circuit : The closed path in which electric current flows. Q3 Under what conditions a circuit is said to be complete? Ans-Current can flow through a circuit only if it is complete i.e. all its parts are made up of a conductor. Q4 What is a switch? Ans -Switch is used to close and open a circuit. When switch is ‘ON’ circuit is complete and current flows through it and when it is ‘OFF’ circuit breaks (air is an insulator) and flow of current stops. Q5 Draw the symbols for various Components of an electric circuit ? Cell : Source of electric current.   Battery : Combination of 2 or more cells  Connecting Wires – generally insulated Copper wires.  Electric Bulb – Key or switch-Open key-Closed key Note : When cells are connected to form a battery positive terminal of one is always connected to negative terminal of the other. Q6 What is a circuit diagram? A