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Chemistry > Principles Of Chemistry > Flashcards

Principles Of Chemistry Flashcards

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0
Q

Atom

A

Smallest component of an element consisting of a nucleus that contains protons, neutrons and electrons (that orbit the nucleus in shells)

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1
Q

Molecules

A

Two or more atoms covalently bonded together. (Monatomic molecules are molecules that contain only one atom - noble gases

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2
Q

Element

A

A substance that cannot be separated or broken down into simpler substances by chemical means

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3
Q

Compounds

A

A substance formed by the chemical combination of two or more elements.

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4
Q

Mixtures

A

Not pure substances but contain two or more substances that are not chemically joined together. (Able to be separated)

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5
Q

Filtration

A

To separate an undissolved solid from a mixture of the solid and liquid

(Eg sand from mixture of sand and water)

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6
Q

Evaporation

A

To separate a dissolved solid from a solution when the solid has similar solubilities in both hot and cold solvent.

(Eg sodium chloride from a solution of sodium chloride in water)

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7
Q

Crystallisation

A

To separate a dissolved solid from a solution when the solid is much more soluble in hot solvent than cold.

(Eg copper(II) sulfate from a solution of copper(II) sulfate in water)

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8
Q

Simple Distillation

A

To separate a liquid from a solution

Eg water from a solution of sodium chloride in water

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9
Q

Fractional distillation

A

To separate two or more liquids that are miscible with one another

(Eg ethanol and water from a mixture of the two)

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10
Q

Paper Chromotography

A

To separate substances that have different solubilities in a given solvent

(Different coloured inks that have been mixed to make black ink)

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11
Q

Relative Atomic mass

A

The weighted average of the masses and relative abundances of all the isotopes of a particular element.

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12
Q

Empirical formula

A

Gives the simplest whole-number ratio of atoms (calculated with knowledge of ratio of masses MOLES)

➡️ divide percentages or grams by molar mass to get moles

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13
Q

Molecular formula

A

Gives the exact numbers of atoms

➡️ divide the given Mr of the molecular by the Mr of the empirical…then multiply all of the empirical by that number

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14
Q

Percentage yield

A

(Yield obtained ➗ theoretical yield) x 100

Mass of reactants ➗ Mr of reactants = moles

Moles x mass of reactants = theoretical yield

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15
Q

The formation of ions

A

Ions are formed by the loss or gain of electrons

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16
Q

Ionic bonding

A

Strong electrostatic forces of attraction between the oppositely charged ions

(Ionic bonding is between a metal and non-metal)

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17
Q

What is the relationship between ionic charge and the melting point and boiling point of an ionic compound?

A

The bigger the difference in charge, the stronger the attraction - higher melting and boiling point. (Eg 3+,3- ions have a higher melting point than 1+,1- ions)

18
Q

An ionic crystal?

A

A giant three dimensional lattice structure held together by the attraction between oppositely charged ions.

19
Q

Ionic compounds conduct electricity?

A

Ionic compounds don’t conduct electricity in solid form but do in molten/liquid form (the positive and negative ions separate and are free to move around so can carry electricity)

20
Q

Covalent bonding

A

Formed by the sharing of a pair of electrons between two atoms so that each completes their outer shell

(Non-metals only - solids, liquids or gases)

21
Q

Attraction in covalent substances

A

Strong attraction between the bonding pair of electrons and the nuclei of the atoms involved in the bond.

22
Q

Simple molecular structures

A
  • Substances with simple molecular structures are gases, liquids, solids with low melting points (low mp and bp because weak intermolecular forces of attraction)
  • poor electrical conductivity - no ions to carry electricity
  • mostly insoluble

E.g. Iodine, CO2, H2O

23
Q

Giant covalent

A
  • High melting and boiling points because no intermolecular forces of attraction (unless graphite) but strong covalent bonds - require energy to overcome
  • poor electrical conductivity (unless graphite)
  • insoluble

E.g. Diamond, graphite, sand

24
Q

Diamond properties and uses

A
  • extremely hard, crystalline, shiny, each carbon atom bonds to 4 other carbons
  • high MP 3500 degrees C bc giant covalent structure, arranged in a giant lattice. 4 carbon atoms covalently bonded to 4 other carbon atoms and there have a very strong attraction between the nuclei of the carbon atoms and the electrons being shared - large amount of energy to break.
  • all 4 electrons are trapped in covalent bonds and can’t move (no conducting of the electricity)
  • cutting tools, jewellery
25
Q

Graphite properties and uses

A
  • very soft, smooth, each carbon bonds to 3 other carbons
  • has delocalised electrons that are free to move between layers so conducts electricity
  • lubricant- they have weak intermolecular forces between layers of molecules which allow layers to slide over each other. Bonds do not break bc also has strong covalent bonds
  • electrodes for electrolysis, lubricant
26
Q

Metallic structures

A

Giant structure of positive ions surrounded by a sea of delocalised electrons

27
Q

Properties of metallic crystals and why

A
  • conduct electricity because the delocalised electrons are free to move when a potential difference is applied across the metal
  • malleable and ductile because the layers of positive ions can easily slide over one another and the delocalised electrons move with them. So they continue to attract each other strongly in their new positions and the metallic bonds are not broken.
  • high mp and bp because the strong metallic bonds require a lot of energy to break.
28
Q

What is an electric current?

A

A flow of electrons or ions

29
Q

Covalent compounds electricity?

A

Don’t conduct electricity because no delocalised electrons - no transfer of electricity through the compound

30
Q

Describe experiments to distinguish between electrolytes and non-electrolytes w LED

A

➡️Set up an electric circuit with an LED and a break in the wire, put both ends of wire into a solution/molten substance.
➡️If LED lights up then there is a current flowing, this will only be able to happen if the solution is conducting: so it must be an electrolyte.

➡️ If LED does not light up then there is no current flowing, and so the solution has not conducted electricity meaning it must be a non-electrolyte

31
Q

What is electrolysis?

A

The breakdown of ionic compounds (molten/in solution) with electricity

(Involves the formation of new substances when ionic compounds conduct electricity)

32
Q

Describe experiments to distinguish between electrolytes and non-electrolytes w conductivity probe

A
  • place conductivity probe in an electrolyte, current flows, measure it’s conductivity
  • when conductivity probe in a non-electrolyte, no current flows, so you’ll get a reading of zero conductivity
33
Q

describe experiments to investigate electrolysis, using inert electrodes, of molten salts such as lead (II) bromide and predict the products.

A

Molten lead bromide splits up into Pb2+ (the cation) and Br2- (the anion)

Pb2 is attracted to the cathode (negative electrode), accepts 2 electrons and becomes a lead atom Molten lead sinks to the bottom

Pb2+ + 2e —> Pb

Br2- attracted to the anode (positive electrode). two bromide ions lose one electron each and become a bromine molecule. Broke gas forms at the top of anode

2Br- —> Br2 + 2e-

34
Q

Why are the electrodes made from an inert (interactive) material?

A

So they don’t take part in the reaction.

35
Q

The products of electrolysing a molten binary compound (2 elements) follow the rules:

A

Metal formed at negative electrode (cathode)

Non-metal formed at the positive electrode (anode)

36
Q

describe experiments to investigate electrolysis, using inert electrodes, of aqueous solutions (sodium chloride) and predict the products

FIX THIS

A
  • NaCl contains the ions: Na+, Cl-, OH-, H+
  • cathode: hydrogen gas bc sodium is more reactive than hydrogen

2H+ + 2e- —> H2

• anode: chlorine gas because OH- and halide ions are present.

2Cl- —> Cl2 + 2e-

37
Q

describe experiments to investigate electrolysis, using inert electrodes, of aqueous solutions (copper (II) sulfate) and predict the products

FOX THIS

A
  • CuSO4 contains Cu 2+, SO4 2-, OH-, H+
  • cathode: copper metal produced bc copper is less reactive than hydrogen

Cu 2+ + 2e- —> Cu

• anode: hydrogen and oxygen produced bc no halide ions present

4OH- —> O2 + 2H2O + 4e-

38
Q

describe experiments to investigate electrolysis, using inert electrodes, of aqueous solutions (sulfuric acid) and predict the products

FIX THIS

A
  • H2SO4 contains SO4 2-, H+, OH
  • cathode: hydrogen bc hydrogen is less reactive than sulfur

2H+ + 2e- —> H2

• anode: oxygen and water bc no halide ions present

2H2O —> O2 + 4H+ + 4e-

39
Q

what does one faraday represent?

A

One mole of electrons

40
Q

How to do faradays calculations?

A
  • write out half equation
  • Q = It (work out C)
  • divide C by 96500 to get F
  • divide F by number of moles to get moles
  • multiply moles by Mr
41
Q

What’s a giant lattice?

A

A giant array of molecules

42
Q

What can nitrogen be used for?

A

In the haver process

43
Q

What can nitrogen be used for?

A

In the haver process

Chemistry (7 decks)

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