Chemistry 2

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  • Created by: tomiaraba
  • Created on: 15-12-15 20:47
What is the difference between a mixture and a compound?
A mixture is when two substances are mixed together but do not change themselves. A compound is a the product of two substances reacting together to form a new substance.
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What is actually forming the bond between two elements in an ionic bond?
The electrostatic attraction between the oppositely charged ions.
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When are ionic compounds usually formed?
When metals and non-metals react.
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Which shell is shown in a dot and cross diagram?
The outermost shell only.
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Why is copper sometimes written as copper (I) or copper (II)?
Because copper is a transition metal and can produce ions with 1+ and 2+ charge.
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What type of bond is usually formed when non-metals react?
Covalent bonding.
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What is a macromolecule?
A giant structure where huge numbers of atoms are held together by covalent bonds.
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What polarity are the ions in metals?
Positive.
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How are the electrons arranged in a metal?
The outer electrons form delocalised electrons which surround the positively charged ions.
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Are the melting and boiling points high or low for ionic compounds?
High.
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What is formed when an ionic compound is dissolved in water?
A solution.
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Are the melting and boiling points high or low for covalently bonded molecules?
Low
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Do liquids made of simple molecules conduct electricity? Why?
No, as each molecule in a compound carries no charge.
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What is an intermolecular force?
A weak force between the individual molecules (not atoms) of a covalent substance.
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Can giant covalent structures usually conduct electricity?
No.
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What triggers the deformed alloy to return to its original shape?
Heat.
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What do the properties of a polymer depend on?
The monomers used to make it.
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What are the abbreviations for the two types of poly(ethene)?
HDPE (high density poly(ethene)) and LDPE (low density poly (ethene).
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What is the difference in the structure of HD and LD poly(ethene)? How does that affect its density?
LDPE is branched and cannot pack closely together whereas HDPE is made up of straighter molecules and can therefore pack more closely.
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What is a thermosoftening polymer and what is the basic arrangement of chains in it?
One that softens quite easily when it is heated but will reset when cooled down. It has individual polymer chains tangled together.
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What is a thermosetting polymer and what is the basic arrangement of chains in it?
One that does not melt when heated. It has chains that are cross linked by strong covalent bonds.
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What are isotopes?
Atoms of the same element with different numbers of neutrons.
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State the similarities and differences in properties of different isotopes.
Isotopes can have different physical properties such as density or radioactivity but always have the same chemical properties.
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What do scientists shorten 'relative atomic mass in grams' and 'relative formula mass in grams' to?
A mole.
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What is the empirical formula of a compound?
The simplest whole ratio of each type of atom in the compound.
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What is the yield of a reaction?
The amount of product that a chemical reaction produces.
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What is the equation for percentage yield?
(amount of product produced/maximum amount of product possible) x 100.
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What is a food additive?
A substance added to food to extend shelf life or improve taste or appearance.
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How does paper chromatography work?
Some compounds in a mixture dissolve better than others in particular solvents; the more soluble they are, the further they travel across the paper.
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How does gas chromatography work?
First, the mixture is vaporised. Then the carrier gas moves vapor through coiled column. Different compounds are slowed by column by different amounts and reach the end at different times. The separated compounds leave the column and are recorded.
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Why do fridges and freezers stop food going off as quickly?
Reducing the temperature reduces the rate at which the food goes off as a result of chemical reactions.
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If a reversible reaction is exothermic in one direction, what will it be in the opposite direction?
Endothermic.
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What type of reaction takes place in hand warmers?
Exothermic.
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What is a base?
A substance that can neutralise an acid.
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What do acids form when we add them to water?
H+ ions.
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What is it that actually makes a solution alkali?
OH- ions.
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When can we react acids with metals?
When the metal is more reactive than hydrogen.
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What is the solid called that is formed when insoluble salts are formed?
A precipitate.
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What is the melting temperature of aluminium oxide?
2050 degrees celsius.
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What is brine?
Concentrated sodium chloride solution.
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What is an electroplated object?
One that has been coated with a thin layer of metal by electrolysis.
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Other cards in this set

Card 2

Front

What is actually forming the bond between two elements in an ionic bond?

Back

The electrostatic attraction between the oppositely charged ions.

Card 3

Front

When are ionic compounds usually formed?

Back

Preview of the front of card 3

Card 4

Front

Which shell is shown in a dot and cross diagram?

Back

Preview of the front of card 4

Card 5

Front

Why is copper sometimes written as copper (I) or copper (II)?

Back

Preview of the front of card 5
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