When atoms of two or more elements are chemically combined together.
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What are isotopes?
Different forms of the same element with the same number of protons, but a different number of neutrons.
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What is Ionic bonding?
Transferring electrons between a metal and a non metal.
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Why is a shell with one electron keen to get rid of it?
Because they like a flu outer (valence) shell therefore is is very REACTIVE.
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What do elements with an almost full shell want to do?
Gain an electron to fill up their outer shell, i e Sodium and Chlorine.
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What structure do ionic compounds have?
A regular lattice structure.
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What are the forces like in a lattice?
Have a very strong electrostatic force of attraction between oppositely charged ions in all directions.
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What are the similar properties of ionic compounds?
1) High melting/boiling points. 2) Carry electric current when melted. 3) Dissolve easily.
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What groups are most likely to form Ions?
1,2,6 and 7.
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What is the name for atoms that have lost or gained electrons?
Ions
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What structure do ions have?
Electronic structure of a noble gas.
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The charge on the positive ions is the same as what?
The group number of the element.
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What is the overall charge of a compound?
Zero.
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What are covalent bonds?
A shared pair of electrons.
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What do molecular substances not contain?
Ions, they cannot conduct electricity.
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Giant covalent structures are...?
Macromolecules.
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Give examples of macromolecules.
Diamond, Graphite, Silicone Dioxide (silica).
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Metal properties are due to what?
The sea of free (delocalised) electrons.
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Why are alloys harder than pure metals?
Because by inserting a new metal into the structure the layers cannot slide over each other as easily.
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How big are nanoparticles?
0.000 000 001m
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Give an example of a smart material?
Nitinol
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What is nitinol?
a shape memory alloy made up of nickel and titanium.
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How many atoms are in a nanoparticle?
Roughly a few hundred.
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What are fullerenes?
Molecules of carbon in hollow balls/closed tubes.
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How are carbon atoms arranged?
In hexagonal rings.
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Uses for nanoparticles?
1) industrial catalysts. 2) sensors. 3) stronger, lighter building materials. 4) cosmetics. 5) Medicine, they are more easily absorbed into the blood. 6) Lubricants and conductors.
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Forces between molecules determine what?
Properties of plastics.
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Strong covalent bonds hold atoms together in long chains, what bonds determine the property of plastic?
Bonds between the different molecule chains.
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How is low density polythene made? (used in plastic bags and bottles)
By heating ethene to 200 degrees under high pressure.
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How is high density polythene made? (used for drain pipes and water tanks)
At a low temperature and pressure with a catalyst.
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What is a relative atomic mass?
How heavy an atom is compared to carbon-12.
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what is the Relative atomic mass usually the same as?
The mass number.
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What number on the element is the mass number?
The biggest one.
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In a compound, how would you calculate the Relative Formula Mass?
All the atomic masses added together.
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The relative formula mass of a substance in grams is known as one ? of a substance?
Mole.
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What is the mole equation?
number of moles = mass in g (of element/compound) / RFM (of element/compound)
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