Revision for Chemistry 2a

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What does the mass number represent?
The total number of protons and neutrons
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What does the atomic number represent?
The number of protons
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What is a compound?
Atoms from two or more elements that are chemically bonded
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Define the term isotope
A different atomic form of the same element, which has the same number of protons but a different number of neutrons
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What happens during ionic bonding?
Atoms lose or gain electrons to form charged particles (ions) which are then strongly attracted to each other due to their opposite charges
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Describe the structure of a crystal of sodium chloride
It is one giant ionic lattice, so the salt crystals tend to be cuboid in shape
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List the main properties of ionic compounds
High melting point, high boiling point, conduct electricity when molten or aqueous, and dissolve easily in water
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When type of ion do elements from group 1 form?
Positive ions with +1 charge
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When type of ion do elements from group 7 form?
Negative ions with -1 charge
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What is covalent bonding?
When atoms share electrons in their outer shells to gain a full outer shell
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What are the two types of covalent substance?
Simple covalent structures and giant covalent structures
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List three properties of metals
1. Can be bent and shaped 2. Good conductors of heat 3. Good conductors of electricity
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Explain why alloys are 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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Give an example of a 'smart' material and describe how it behaves
Nitinol is a shape memory alloy, so if you heat it above a certain temperature it goes back to a 'remembered' shape
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What are nanoparticles?
They are really tiny particles about 1-100 nanometres across
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Give two different applications of nanoparticles
They are sued in cosmetic products (e.g. suncream) and and they can also help make new industrial catalysts
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Explain the difference between thermosetting and thermosoftening polymers
Thermosetting polymers have crosslinks which hold the polymer chains firmly together, whereas thermosoftening polymers don't have crosslinks so the polymer chains are free to slide over each other
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What is the relative atomic mass
It is the same as the mass number
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Define relative formula mass
It is the sum of all the relative atomic masses of the elements within a compound
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What is the link between moles and relative formula mass?
One mole of a substance is the relative formula mass in grams
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What is an empirical formula?
It is the formula of a compound
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Name three factors that can reduce the percentage yield of a reaction
1. The reaction is reversible 2. Filtration 3. Unexpected reactions
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List three advantages of using machines to identify elements and compounds
1, Very sensitive (can detect the tiniest amounts of substances) 2. Very fast and tests can be automated 3. Very accurate
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Other cards in this set

Card 2

Front

What does the atomic number represent?

Back

The number of protons

Card 3

Front

What is a compound?

Back

Preview of the front of card 3

Card 4

Front

Define the term isotope

Back

Preview of the front of card 4

Card 5

Front

What happens during ionic bonding?

Back

Preview of the front of card 5
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