Chemistry 2a- Bonding and calculations. QUESTIONS AND ANSWERS- ALL YOU NEED FOR C2A

What is the mass number?
The total number of protons and neutrons
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What is the atomic number?
The total number of protons
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What are compounds?
Formed when two or more elements are chemically combined together.
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What are isotopes?
THye are different atomic forms of teh same elements which have the same number of protons but a different number of neutrons
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What is ionic bonding?
Where atoms lose or gain elections to form charged particles that are strongly attracted to one another due to the opposite charges.
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Why do atoms want a full outer shell?
Because they are most stable with a full outer shell
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What type of structure do ionic compounds have?
They have a regular lattice structure.
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What type of forces are in a giant ionic lattice?
There are strong electrostatic forces of attraction between the oppositely charged ions.
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Name a giant ionic lattice
Sodium chloride.
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What are some properties of giant ionic lattices?
High melting point, high boiling point, dissolve easily in water.
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Which groups are most likely to form ions?
1&2, 6&7
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What is covalent bonding?
Where atoms bond by sharing electrons to have a full outer shell
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What are simple molecular substances?
A product of strong covalent bonds to form small molecules of atoms.
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What type of forces are in simple molecular substances?
Wear intermolecular forces.
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What are some properties of simple molecular substances?
Low melting and boiling points, gas/liquid at room temperature, don't conduct electricity
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What are giant covalent structures?
Atoms bonded together with strong covalent bonds, but no charged ions.
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What type of forces are in giant covalent structures?
Strong intermolecular forces.
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What are some properties of giant covalent structures?
Don't conduct electricity, high melting and boiling points.
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What are some properties of a diamond?
Each carbon atom forms four covalent bonds, making it very hard.
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What are some properties of silica?
Each grain of silica (sand) is a giant structure of silicon and oxygen.
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What are some properties of graphite?
Each carbon atom forms three covalent bonds, creating layers that slide over eachother. It's a non metal but is a good conductor due to each carbon atom having one delocalised election.
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Why do metals conduct?
Because of the sea of free electrons from the outer shell of every metal atom in the structure.
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Why are alloys harder than pure metals?
They include different sized atoms to distory the layers of metal atoms making it harder for them to slide over eachother
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What are smart materials?
They behave differently depending on the conditions
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What are nanoparticles?
They are 1-100 nanometers long, and contain a few hyndred atoms.
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What are some properties of nanoparticles?
They have large SA to Volume ratio, conduct electricity and are clear on skin.
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What are thermosoftening polymers?
Polymers that don't have crosslinks between chains, so they bonds are easy to overcome and therefore melt.
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What are thermosetting polymers?
Polymers with crosslinks, holding the chains together in a solid structure. They don't soften when heated and are strong and hard.
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How is Low Density polythene made and what are some properties?
Made by heating ethene to 200 degrees c under high pressure. Flexible.
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How is High Density polythene made and what are some properties?
Made at a low temperature and low pressure, is more rigid.
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How do you calculate relative formula mass?
It is all the relative atomic masses of the elements in the formula added together.
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What is one mole?
It is equal to its relative formula mass, but in grams.
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What is the equation for the number of moles?
Mass in G / Relative formula mass
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How do you calculate % mass of an element in a compound?
Relative atomic mass x Number of atoms of that element / Relative formula mass of whole compound (x100)
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What is the empirical formula?
The simplest formula for a compound
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How do you find the empiricle formula?
List the elements in the compound and underneath write the expermimental masses. Then divide each mass by the Relative Atomic mass of that element, and turn the numbers into a ratio.
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What is percentage yield?
Actual yield / Predicted yield (x100). It's the amount of produdct that is actually produced in the end
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Why are yields always less than 100%?
There are three reasons: The reaction could be reversable, filtering a liquid could be lost when filtering a liquid, or unexpected reactions occur and use up the reactants
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What is paper chromatography?
Seperating dyes by putting spots of the coloured solution on a pencil baseline, putting the sheet into a beaker with solvent in, and seeing what colours seep out of the original dye
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What is gas chromatography used for?
Used to seperate out a mixture of compounds to identify the substances.
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How does gas chromatography work?
Substances travel through a colum at different speeds, so they're seperated.
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Other cards in this set

Card 2


What is the atomic number?


The total number of protons

Card 3


What are compounds?


Preview of the front of card 3

Card 4


What are isotopes?


Preview of the front of card 4

Card 5


What is ionic bonding?


Preview of the front of card 5
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i need help with describing the sodium chloride crystal structure 

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