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13 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What does the mass number tell us ? |
Total number of protons and neutrons in an atom . |
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What does the atomic number tell us ? |
The number of protons in an atom . |
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How are compounds formed ? |
1) compounds are formed when atoms of tow or more elements are chemically combined together . 2) it's difficult to separate the two original elements out again . |
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What is an isotope ? |
Isotopes are different atomic forms of the same element , which have the same number of protons but a different number of neutrons . |
Isotopes are different atomic forms of the same element , which have the same number of protons but a different number of neutrons . |
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What are the properties of a giant covalent structure ? |
1) all the atoms are bonded to each other by strong covalent bonds . 2) this means that they have very high melting and boiling points . 3) they don't conduct electricity • main examples are diamond and graphite , both made only from carbon atoms , and silicon dioxide . |
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What are the properties of diamond ? |
Each carbon atom forms 4 covalent bonds in a very rigid giant covalent structure . This structure makes diamond the hardest natural substance , so it's used for drill tips. |
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What are the properties of silicon dioxide ? |
It is sometimes called silica , t is what sand is made of . Each grand of sand is one giant structure of silicon and oxygen . |
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What are the properties of graphite ? |
• Each carbon atom only forms 3 covalent bonds . This creates layers which can slide over each other . • the layers are held together loosely by weak intermolecular forces . • Graphite is the only non - metal which is a good conductor of heat and electricity . Each carbon atom has one delocalised electron and it's these free electrons that conduct heat and electricity . |
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What are the properties of metals ? |
• metals consist of giant structures. • they have free elections in every outer shell . • the elections are free to move through the whole structure and so metals are conductors of heat and electricity . • these electrons also hold the atoms together in a regular structure . There are strong forces of electrostatic attraction between the positive metal ions and the negative electrons. • they also allow the layers of atoms to slide over each other , this allows metals to be bent and shaped . |
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Why are alloys harder than pure metals ? |
Different elements have different sized atoms . So when another metal is mixed with a pure metal , the new metal atoms will distort the layers of metal atoms making it more difficult for them to slide over each other . |
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What are the properties of thermosoftening polymers ? |
• don't have cross - linking between chains. • the forces between the chains are really easy to overcome , so it's easy to melt the plastic. • when it cools the polymer gardens into a new shape . • you can melt these plastics and remould them as many times as you like . |
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What are the properties of a thermosetting polymer ? |
• they have cross links . • they hold the chains together in a solid structure . • the polymer doesn't soften when it's heated . • they are strong , hard and rigid. |
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How do you find one mile of a substance ? |
Number of moles = mass in g ( of element or compound ) divided by : Mr ( of element or compound ) |
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