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Description
Flashcards by James Middleton7674, updated more than 1 year ago
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Created by James Middleton7674
about 9 years ago
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| Question | Answer |
| What are the two types of bonding and what is the difference between them? | Covalent - non metals combine by sharing electrons Ionic - metals and non metals combine by transferring electrons |
| One example of covalent bonding is the molecule Cl2. Another is H20 either use a diagram or in words explain the covalent bonding between the hydrogen and oxygen. | Use book (pg 60) for diagram. Oxygen atom shares a pair of electrons with each hydrogen atom to form water. |
| What are the properties of simple covalently bonded molecules? | the bond between two atoms in a simple covalently bonded molecule (e.g. water or carbon dioxide) is very strong. The intermolecular forces of attraction between molecules are weak. This results in them having low melting points. They do not conduct electricity as they don't have a free electron. |
| If an element is in group 7 then how many electrons does it have in its outer shell and where can you find a group in the periodic table? | It has 7 electrons in its outer shell you can find groups by looking at a vertical column of the table. |
| What do periods tell us and how do you find a period in the periodic table? | It tells you how many shells of electrons the element has and you find it by looking across horizontally. |
| What did Johann Dobereiner do in the discovery of the periodic table? | Johann Dobereiner - First scientist to arrange elements in pattern, discovered that elements with similar properties made triads ie chlorine, bromine and iodine. He noticed that the atomic weight of the second element was average of the other two. Some elements did not fit and could not be put into a triad, he published his idea in 1817 |
| What did Demitri Mendelev do in the discovery of the periodic table? | Refined John Newlands ideas which were the law of octaves which was not accepted at the time of publication. He refined it by putting all known data for each element which he arranged in groups and periods in weight order based on their properties. If the weight order contradicted the properties of two elements he swapped them to maintain his pattern. He left gaps for undiscovered elements and predicted their properties. His theory was not first accepted but when Gallium was found to have the properties he had predicted it was accepted. Scientist now know that atomic weight order is incorrect and we sort by atomic number. |
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