Mutchus

4.6 Cells and Batteries Key Points 1. An electric cell consists of two electrodes and an electrolyte. 2. Primary cells cannot be recharged, while secondary cells are rechargeable. 3. The zinc-acid cell is not commercially produced because it suffers from polarization and local action. 4. Polarization in cells is the process during which gas bubbles form on an electrode thereby insulating it from the chemical reactions of the cell. 5. Local action is the formation of local cells on the zinc electrode due to iron or lead impurities. 6. The Leclanché cell is the most commonly used wet or dry cell. It consists of a zinc cathode, a carbon anode, sal ammoniac electrolyte and a depolarizer. 7. The dry cell is manufactured in four sizes: D, C, AA and AAA. 8. The mercury cell is constructed small in size for powering small gadgets. It has a very high energy output for its size but due to its high mercury content it has been superseded by silver oxide, zinc air and lithium air cells. 9. ...

3.4 Atomic Structure Definition Key Points 1.         Matter is anything that occupies space and has mass. 2.         The smallest particle of matter that can take part in a chemical reaction is called an atom. 3.         An atom consists of protons, neutrons and electrons. 4.         The protons and neutrons form the nucleus of the atom. 5.         Protons and neutrons are collectively known as nucleons. 6.         The atomic number of an element indicates the number of protons in the nucleus of its atom. 7.         The number of electrons in the outermost orbit is the valence electrons. 8.         Electrons carry a negative charge; while protons carry a positive charge. Charged atoms or molecule are called ion...