C2 Chemistry

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  • Created by: wafflypig
  • Created on: 15-04-16 14:12
Give 3 properties of an electron
Tiny, almost no mass, move around the nucleus, negative charge,
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Give 3 properties of a nucleus of an atom
Contains protons and neutrons, center of centripetal force, overall positive charge, bigger than the electrons but small compared to space occupied by the atom
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The number of electrons is the same as...
The number of protons
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What is the relative mass of an electron?
1/1860 (or rounded to 1/2000)
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What is the relative charge and mass of a neutron?
Charge: 0 Mass: 1
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What does the top number of an element of the periodic table represent?
The number of nucleons (protons + neutrons) in the nucleus
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What does the bottom number of an element in the periodic table represent
Number of protons (and number of electrons)
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Other than the first energy level, what is the maximum amount of electrons between 2s and 3s?
8
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How many electrons in the first shell?
2
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How many types of atom does a single element contain?
1 only
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The number of which nucleon defines the element?
Proton
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What is the top number on the periodic table called?
Mass Number
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What is the bottom number on the periodic table called?
Atomic Number/Proton Number
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How can you find the total number of neutrons in an atom?
Mass number - atomic number
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What are isotopes?
Different atomic forms of the same element, containing the same of protons but a different number of neutrons
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Where can relative atomic mass be found on the periodic table of the elements?
Mass number (top)
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What is the acronym for relative atomic mass?
Ar
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What is relative abundance?
How much of an isotope there is, taking into account the total amount of the element in the world. Can be a ratio
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Ar = ....
(Mass of isotope*relative abundance of isotope)(Mass of isotope*relative abundance)/relative abundance + relative abundance
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Who arranged the elements into the periodic table, originally?
Dimitri Mendeleev
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How did Mendeleev predict new elements would be discovered?
By leaving gaps in his ordering
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How did Mendeleev know to leave gaps?
He ordered elements with similar chemical properties vertically. He had to leave gaps for this to be true
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What are vertical lines of elements on the periodic table called?
Groups
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What are the horizontal elements on the periodic table called?
Periods
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A whole new group has (relatively) recently been added to the periodic table. What was it?
Group 0/Noble Gases
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Why did it take longer to discover the noble gases?
The are very unreactive
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Which side of the table are metal on?
Left
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What is to the right of the staircase on the periodic table?
Non-metals
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If you move down by 1 period in a group (eg Li to Na), what happens to the number of electron shells?
Increases by 1
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What does group number have to do with the number of electron shells?
The amount of electrons in the outer shell is equal to the group number. E.g. Na has 1 electron in its outer shell
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What group are the halogens in?
7
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What group are the alkali metals in?
1
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Why are they called alkali metals?
They produce an alkaline solution after reaction
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What is ionic bonding?
The chemical bonding of atoms through electron transfer
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What are ions?
Charged particles (eg lost an electron or gained on)
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What charge does a cation have?
Positive (CATS HAVE PAWS)
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What charge does an anion have?
Negative
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If an atom gains electrons, what does it become?
Anion, negatively charged ion
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Why are group 4 elements unlikely to form ionic bonds?
They have 4 electrons in their outer shells so it's just as hard to gain and lose 4 electrons
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What method can be used to write an ionic formula?
Cross over method
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Which 4 groups are most likely to form ions?
1, 2, 6 and 7
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What 2 things affect how easily an atom loses electrons?
Distance from +ve charge of nucleus (further away = easier to go) and the amount of electron shells in between shielding the electrostatic forces of attraction between electrons and the overall +ve charge of the nucleus
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What are the 3 properties of an ionic compound?
Conduct electricity when molten/dissolved and have high melting/boiling points, form an ionic lattice
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Why do ionic substances have high melting boiling points?
They have very strong electrostatic intermolecular forces of attraction which require lots of (thermal) energy to break
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Why do ionic substances only carry charge when aqueous or molten?
Because the ions (NOT ELECTRONS) must be free to carry around charge
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What kind of compounds end with "...ate"
Ones that contain 3 or more elements
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What elements make up copper sulphate?
Cu, S and O
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The rules of solubility say that, all nitrates are...
Soluble
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The rules of solubility say that, common salts of sodium, potassium and ammonium are...
Soluble
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The rules of solubility say that, chlorides are....
Soluble except silver and lead
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The rules of solubility say that, sulphates are...
Soluble except lead, barium and calcium
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The rules of solubility say that, carbonates and hydroxides are...
Insoluble except sodium, potassium and ammonium
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What colour flame does potassium have?
Lilac
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What colour flame does copper have?
Blue/Green/Turquoise
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What colour flame does calcium have?
Brick red
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What colour flame does sodium have?
Yellow (NOT ORANGE)
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Why can barium sulphate be used for xrays (aka barium meals)?
It is very insoluble so doesn't get into blood and carry toxins around. It is opaque to xrays and can show intestine abnormalities
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How can you make a metal loop clean for flame tests?
Dip in hydrochloric acid and rinse in distilled
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Acid + carbonate -> ....
salt + water + carbon dioxide
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How can you test for carbonate ions?
Bubble the gas through limewater
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How can you test for sulphate anions?
Add HCl, add BaCl2. White precipitate = sulphate present
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How can you test for chloride anions?
Add HNO3, add AgNO3. White precipitate = chloride present
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How does a spectroscopy machine work?
Analyses the patterns of light emitted by a sample of element to be tested
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Which element was originally called Aurum?
Gold hence, Au
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What is covalent bonding?
A shared pair of electrons
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What are the common double covalent substances?
Carbon dioxide and oxygen
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What is the formula for ammonium?
NH4+
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To how many hydrogen atoms does the carbon atom bond to make methane?
4. (CH4)
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Which 2 elements are never found as single atoms?
Oxygen and hydrogen
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How strong are the intermolecular forces in simple covalent substances?
Weak
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What are the properties of simple molecular substances?
Low boiling/melting point (weak IM forces), gases/liquids at room temperature, do not conduct
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Give 2 examples of giant covalent substances
Diamond and graphite
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What is the formula for diamond?
C. It is an allotrope of carbon, as is graphite
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Give 3 properties of giant molecular substances
Very high melting/boiling point, insoluble in water, all atoms are bonded by strong covalent bonds, except graphite - they do not conduct
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Why is graphite a good conductor?
There lots of delocalised electrons because graphite has only used up 3 of the possible 4 covalent bonds with carbon. These electrons can move and carry charge
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Why is graphite a good lubricant?
The layers slide over each other because there are weak forces between the layers
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How many bonds to another carbon atoms are there for each atom in diamond?
4
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Define miscible
Liquids that will mix together
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Define immiscible
Liquids that do not mix, they form layers
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How can you separate immiscible liquids?
With a separation funnel - turn the tap off and let the bottom liquid run out into a separate beaker
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How can you separate miscible liquids?
Fractional distillation
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Describe the process of fractional distillation of air
Filter to remove dust. Cool to -200C so it's a liquid. During cooling, water vapour is collected. CO2 is frozen and removed. What is left is put into the column and heated gently. N comes out the top and is collected. O and Ar come together, repeat
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What is the Rf value?
The ratio of the distance travelled by substance and solvent
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Rf = ....
Distance travelled by substance / Distance travelled by solvent (HINT: 99% of the time it is a decimal)
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What can chromatography be used for?
To identify the contents in a mixture. It uses the idea that substances move through filter paper at different rates
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What 2 industrial uses does chromatography have?
Drug and food testing
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Give 2 properties of transition metals
Form colourful compounds and have high melting points
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Give 2 properties of all metals
Conduct electricity (good for wires), malleable (good for car bodies)
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What type of bonds hold metals together?
Metallic
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What is metallic bonding?
The force of attraction between the many delocalised (outtermost usually) electron that "glue" metal ions together by strong electrostatic forces of attraction
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Why do metals have high melting/boiling points?
The strong electrostatic intermolecular forces of attraction from the delocalised electrons need lots of energy to break
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Give 3 visible properties of alkali metals (group 1)
Soft, shiny after cutting (hasn't reacted with O2), low melting points.
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Name 3 elements in group one
Lithium, Caesium, Sodium, Potassium, Francium, Rubidium
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What happens to the level of reactivity as you move down the group (increase atomic number)?
Increases proportionally
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What happens when Li is added to water containing UI?
It moves around the surface slowly, fizzing and turning the UI pink until it dissappears
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What happens when Na is added to water containing UI?
Moves around the surface quickly, may ignite and will turn the UI pink. A quicker reaction than Li
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What happens when K is added to water containing UI?
Will quickly burn with a lilac flame and may explode. Turns the UI pink and a very fast reaction
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Sodium + Water -> ....
Sodium hydroxide + HYDROGEN
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Why do alkali metals float on water?
They have a lower density
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What are the group 7 elements called?
The halogens
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At room temperature, what are the properties of Chlorine?
Poisonous, dense green gas
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At room temperature, what are the properties of Bromine?
Poisonous, dense brown liquid
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At room temperature, what are the properties of Iodine?
Dark grey crystalline solid
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What is formed when halogens react with hydrogen?
Hydrogen halides
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What is formed when halogens react with a metal?
Metal halides
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What will more reactive halogens do to less reactive ones?
Displace them
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Which way (up or down the group), does reactivity increase?
Up
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What is a displacement?
When less reactive ions are pushed out of a solution by more reactive ones
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What are group 0 gases aka?
Noble gases
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Why are the noble gases unreactive?
They have a full outer shell of electrons so do want or need to react with anything
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Why is argon used to fill light bulbs?
It is unreactive and flame resistant so it stops the hot filament from burning away
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Why do helium balloons float in air?
It has a lower density than air
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Why is argon used as an atmosphere for welding?
It stops the metal from reacting with oxygen in the normal atmosphere
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What 2 things increase as you move down group 0?
Density and boiling point
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What is an exothermic reaction?
A reaction that gives out heat energy, making the temperature rise. Bonds will form
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What is an endothermic reaction?
A reaction that takes in heat energy from the surrounding area, shown by a decrease in temperature. Bonds will form.
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On a graph, do the products end up higher or lower than the reactants in an exothermic reaction?
Lower
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What 4 things does the rate of reaction depend on?
Catalyst, temperature, concentration and surface area
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What is a catalyst?
A substance which changes the speed of reaction (lowers activation energy) without being used up itself.
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Give an industrial use of catalysts
In catalytic converters in car exhausts. Burns off poisonous CO
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What is the only way you can increase the speed of collisions?
Increasing the temperature
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How can you calculate formula mass (Mr)?
Add up the Ars of each element in the substance (don't forget to include subscripts and coefficients)
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What is empirical formula?
The simplest ratio of elements in a substance
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Percentage mass = ....
(Ar * number of atoms / Mr) * 100
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Percentage yield = ...
(Actual yield / theoretical yield) * 100
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What is meant by the term, theoretical yield?
The maximum amount that can be expected to be made in a reaction, in theory. This is never reached
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Why does the waste from reactions cost money?
Disposal costs (if dangerous) and it is not commercially useful
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Why are actual yields less than 100% of the theoretical yield?
Incomplete reactions, practical losses during preparation, unwanted reactions
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Give 3 properties of a nucleus of an atom

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Contains protons and neutrons, center of centripetal force, overall positive charge, bigger than the electrons but small compared to space occupied by the atom

Card 3

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The number of electrons is the same as...

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Preview of the front of card 3

Card 4

Front

What is the relative mass of an electron?

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Card 5

Front

What is the relative charge and mass of a neutron?

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