If you’re not fully confident about atomic structure then go back and visit the atomic structure page again as this work builds upon the knowledge you should have from that topic.
This topic is what Chemistry is all about. The electron. It is the location of the electrons that governs reactivity, from elements that don’t react to those that react explosively – it’s all about electrons and their location.
Once you understand that then Chemistry starts to make sense. You can predict reactions, you can understand formulae and you can explain properties of substances – all from your knowledge of the movement of electrons from one element to another, so take your time and make sure you fully understand the basics before moving onto the questions.
All atoms want to have a full outer shell of electrons as this represents a stable energy configuration. In oder to achieve that they can give and take electrons (ionic bonding) have delocalised electrons (metallic bonding) or share electrons (covalent bonding).
Ionic bonds are between metals (on the left of the periodic table) and non-metals (on the right of the periodic table).
Metals want to lose electrons and non-metals want to gain electrons in order to have a full outer shell.
Once an atom changes it number of electrons it becomes an ION. This is because the balance between positive protons and negative electrons has been altered and the atom has become charged (an ion).
Atoms that lose electrons become positive, those that gain electrons become negative with 1 unit of charge per electron. (can you explain why?)
We can’t just create or destroy electrons they can only move around so if an atom wants top lose an electrons there must be another atom close by that wants to gain electrons.
This will result in 2 oppositely charged ions and opposite ions attract to form an ionic bond.
Lots of ionic bonds results in a Giant Ionic Lattice. You must be able to link ionic structure to properties of ionic compounds..
With metals, there is nothing to gain the electron so each metal atom loses its outer electrons to make positive ions but the electrons float around the positive ions as delocalised electrons. This structure explains the properties of metals and you must be able to link structure to properties and function.
Covalent compounds share electrons in order to obtain that full outer shell of electrons. You must know the difference between molecules that are Simple Covalent and those that are Giant Covalent. Why are Simple Covalent molecules either gases or liquids? Why are Giant Covalent molecules solids with very high melting points? Use knowledge of bonding to explain properties of compounds.
Summarise your knowledge using the worksheets
You can be asked to explain the properties any metal and any salt in the exam. Jut apply the same reasoning and explanations to any example you are given. Labelled diagrams always help. In explain questions you must always link structure to function.
Copper is used in all electrical wires, explain why?
Why is sea water a better conductor of electricity than pure water?
Lightning conductors on the roofs of tower blocks and churches become less efficient over time when exposed to the weather. Explain why.
Diamond and Graphite are allotropes of carbon. What is an allotrope? Explain why Diamond is very hard and used on the tips of drills to drill through very hard solids, but graphite is soft and often used as a lubricant.
Water, Nitrogen, silicon dioxide and graphene are all composed of covalent bonds. Describe how a covalent bond forms and compare and contrast the structure and properties of each
Exam Question Practice – gcsescienceteacher
Review and Rate your Understanding
Try the questions below (answers given) then review your understanding
Have you learnt all the facts on the 100% sheet?
Have you completed the BBC Bitesize tutorial?
Have you been able to complete all the questions on the 100% sheet?
Let us know how you feel about this topic in the comments section below. Any questions you have, just ask.