This tells us the number of protons and neutrons in the nucleus of an atom
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What is the definition of an isotope?
Isotopes are atoms of the same element which have the same number of protons but a different number of neutrons.
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What is an ion?
A changed particle formed when an atom either gains or loses electrons.
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Why are ionic compounds crystalline at room temperature?
The positive and negative ions are packed closely together and are held by strong electrostatic attractions
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Why do ionic compounds have high melting points?
As lots of heat energy is needed to separate the oppositely charged ions due to strong electrostatic attractions.
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Name 3 properties of Giant ionic structures
1)High melting and boiling points 2)Hard 3)Crystalline 4)Most are soluble in water 5)Good electrical conductors when melted or dissolved. Don not conduct when solid 6)Brittle
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Why do Giant ionic structures form crystals?
Because the ions are arranged in a regular repeating pattern.
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Why do Giant Ionic structures not conduct when solid?
As the ions, although charged, are tightly held and do not move. When dissolved, or melted, the ions are separated and can move, they carry charge as they move, this is electricity.
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Why are Giant Ionic structures hard to scratch?
They are hard to scratch, due to the strong ionic bonds between the oppositely charged ions.
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What can the moving electrons in a giant metallic structure be called?
Mobile, valance, delocalised electrons
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Name 2 properties of Giant Metallic Structures
1)High melting and boiling points 2)malliable 3)ductile 4)strong/hard 5)dense 6)Good conductors of electricty when solid or melted 7)Shiney
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Why are Giant Metallic structures malleable and ductile?
As when a force is applied the layers of ions absorb it by sliding over each other, and so changing shape without breaking the non directional metallic bonds.
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What is a covalent bond?
A shared pair of elcetrons between 2 atoms
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name 2 Properties of simple covalent structures.
1)Most are gases and liquids 2)Low melting and boiling points 3)Usually insoluble in water 4)Any solids are soft and brittle
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Why are most Simple covalent structures gases and liquids?
As it does not take much heat energy to separate the molecules, as the forces between molecules are weak.
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name 2 Giant covalent structures
Diamond or graphite.
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Give 2 properties of Diamond
1)High melting and boiling point 2)Very hard 3)Crystalline 4)Does not conduct electricity
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Why is diamond hard to scratch or cut?
As there are millions of strong covalent bonds which make it hard to scratch.
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What can diamond be used for?
1)Jewelry (because its crystalline) 2)Drill bits (because its hard)
Because whe a force is applied, the weak forces between layers are easily broken, sliding the layers over each other
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What can graphite be used for?
1)As a lubricant- because it is soft and slippery 2)In pencils-because it flakes easily 3)As electrodes- because it conducts electricity and is unreactive
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What is an allotrope?
Different forms of the same element, in the the same physical state
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