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Chemistry > C2 > Flashcards

C2 Flashcards

1
Q

What is Relative Atomic Mass (Ar)

A

the mean mass of an atom for an element compared to 1/12 of the mass of a Carbon 12 Atom

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2
Q

What is Relative Formula Mass (Mr)

A
  • Mean mass of a unit of substance compared to the mass of 1/12 of a carbon-12 atom
  • Ar of all substances added together
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2
Q

Empirical Formula?

A
  • most simplified chemical formula ratio possible
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3
Q

What is a pure substance?

A

a pure substance is someting made up of only one type of particle

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4
Q

How to determine whether a substance is pure?

A
  • a pure substance will have a single melting temperatue, while an impure substance will have a range
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5
Q

Filtration

A
  • separates an insoluble solid from a liquid
  • pass the solution through a funnel with filter paper into a conical flask and the solid will be left in the filter paper while the liquid goes into the flask
  • residue is solid left behind, filtrate is liquid passed through
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6
Q

Crystallisation

A
  • separates a soluble solid from a liquid
  • the solution needs to be heated gently, the water will evaporate leaving a saturated solution which will leave the solid and it will form crystals
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6
Q

Simple Distillation

A
  • separates a solvent from a solution
  • it relies on the solvent having a muhc lower boiling point than the the solute
  • the solution is heated in the spherical flask to the boiling temp of the solvent
  • the solvent evaporates and cools down and runs down the condestaion tube as a liquid into a test tube where the purified solvent is collected
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7
Q

Fractional Distillation

A
  • separates 2 or more substances in a mixture in the liquid state
  • uses a fractionating column
  • heated to first liquids boiling point
  • this will condesne and be pure while the rest of the solution is still in the flask
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8
Q

Paper Chromatography

A
  • has a stationary phase (paper)
  • and a mobile phase (solvent)
  • a phase is a substance in the solid, liquid or gas state
  • measures the attraction of different liquids to either the mobile or the stationary phase
  • can compare to known substances using Rf value ( distance moved by substance/ distance moved by solvent )
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9
Q

Thin-Layer Chromatography

A
  • stationary phase is thin layer of silica or alumina power
  • mobile phase is liquid solvent
  • depending on attraction, a substance more attracted to the mobile phase will move faster through the stationary phase and have a higher Rf value
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10
Q

Gas Chromatography

A
  • stationary phase is silica or alumina powder in a metal column
  • mobile phase is an unreactive carrier gas
  • each different substance takes different times to travel through the column
  • the computer produces a chromatogram based on this data
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11
Q

Each element in a period has

A

same number of shells

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12
Q

Each element in a group has

A

same number of electrons on the outer shell

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13
Q

Properties of Metals

A
  • shiny
  • malleable
  • high boiling and melting temperature
  • ductile ( can be pulled into wires)
  • good conductors of heat and electricity
  • generally solid at room temp
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14
Q

Properties of Non-Metals

A
  • brittle
  • dull
  • low melting and boiling points
  • liquid or gas at room temp
  • good insulators
  • not ductile
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15
Q

Chemical Properties of Metals

A
  1. Metals lose electrons to form positive ions
  2. Metal Oxides dissolve in water to form alkaline solutions
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16
Q

Chemical Properties of Non-Metals

A
  1. Gain electrons to form negative ions
  2. Non-Metal Oxides dissolve in water and form acidic solutions
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17
Q

Ionic Bonds

A
  • Occur between metals and non metals
  • electrons are transferred from the metal atom to the non metal atom making the metal a postive ion and the non metal a negative ion, both with fuller outer energy shells
  • Ionic Compunds are arranged in a giant ionic lattice ( + and - arranged regularly )
  • Held by ionic bonds which are electrostatic forces of attraction between 2 oppositely charged ions
  • act in all directions
18
Q

Covalent Bonds

A
  • between 2 non metal atoms
  • electrons are shared
  • a simple molecule is a molecule that only contains a few atoms
  • Covalent bonds have electrostatic forces of attrcation between the nucleus of each atom and the shared electrons (directional unlike ionic)
    Covalent bonds between atoms are strong but intermolecular forces between molecules is weak
19
Q

Properties of Diamond

A
  • forms 4 covalent bonds with each carbon atom
  • allotrope of carbon
  • extremely strong covalent bonds with electrons fixed in place
  • extremely hard
  • does not conduct electricity
  • High melting point
20
Q

Properties of Graphite

A
  • Each carbon atom forms 3 covalent bonds (1 delocalised electron)
  • very high metlting point
  • soft, as the layers of carbon can slide past each other
  • delocalised electrons so can conduct electricity
  • strong covalent bonds
  • forces between layers are weak
21
Q

Properties of Fullerenes

A
  • High Tensile strength
  • Good conductor of electricity (delocalised electron)
  • unreactive
  • large surface area to volume ratio
  • make hollow structures ( can be used for drug delivery)
22
Q

Uses of Fullerenes

A
  • Reinforcing materials like sports equipment
  • electronics, chips and curved screens
  • Drug Delivery in the body
  • Lubricants
  • catalayst
23
Q

Polymers

A
  • made of many of the same particle called monomers joined together to make a polymer via covalent bonds
  • e.g ethene can join together and form polyethene
  • eg propene can join together and form polpropene
24
Q

Thermosetting Polymers/HDPE

A
  • chains of polymers are joined together by strong covalent bonds
25
Q

Thermosoftening Polymers / LDPE

A
  • polymer chains are tangled, this has a lower melting point as it is not cross linked
26
Q

Definition of metallic bonding

A
  • the electrostatic attraction between a lattice of positive metal ions and sea of delocalised electrons
27
Q

What are delocalised electrons

A
  • electrons that are lost from outer shells of atoms/ions
  • they float in place and can move freely throughout
  • Delocalised Electrons are why metals can conduct heat and current as the electrons can carry it throught the material
28
Q

What are metal alloys and why are they good?

A
  • mixture of a metal or one or more other diff substances
  • The irregular atoms in between from the other substances means the regular layout is broken and that means they are stronger and less malleable and ductile
29
Q

Properties of Ionic Compounds

A
  • Dissolve in water, they separate positive and ngeative ions
  • Have high melting and boiling points as the bonds between ions are strong as electrostatic forces between ions are strong
30
Q

Properties of Ionic Compounds in Liquids

A
  • Can conduct electricity as ions can move around and carry charge
31
Q

Properties of Small Covalent Molecules

A
  • strong covalent bonds BETWEEN ATOMS
  • however small molecules have weak forces BETWEEN MOLECULES
  • low metling and boiling points (weak forces between molecules break, not interatomic)
  • gases or liquids at room temp
  • Do not conduct electricity as all electrons used in covalent bond
  • Sometimes dissolve in water
32
Q

Properties of Giant Covalent Molecules

A
  • High melting and boiling points
  • does not dissolve in water
  • does not conduct electricity except graphite
33
Q

What are the uses of nanoparticles?

A
  • medicine (drug delivery)
  • cosmetics (suncreams, deodorants)
  • electronics (conductive materials)
  • Catalysts (High SA:V)
34
Q

Disadvantages of Nanoparticles

A
  • risks we do not know about yet
  • may absorb into the body
35
Q

Size of Nanoparticles

A

1-100 nm

36
Q

What is a formulation?

A

A mixture that has been designed as a useful product

37
Q

What are RF vakues used for?

A
  • comparison to other samples to see if the RF values are the same (if they are its that element)
38
Q

Limitations and Advantages of Displayed Formula?

A
  • does not show 3d shape
  • does not show the movement of electrons
  • shows 2d shape
39
Q

Limitations and Advantages of dot and cross model?

A
  • shows the outer shell of electrons
  • shows 2d shape
  • no 3d shape
  • no movement of electrons shown
40
Q

Limitations and Advantages of the ball and stick diagrams?

A
  • good for seeing 3D shape
  • size of atoms and length of bonds are not to scale
  • does not show movement of electrons
41
Q

What are 2 common giant covalent elements?

A

CARBON AND SILICON

42
Q

properties of graphENE

A
  • very low density
  • strong for its mass
  • electrical conductor
  • 1 layer thick
  • based on graphite
43
Q

whats a nanometre in metres?

A

10x-9m

Chemistry (10 decks)

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