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Year 11 Chemistry Atar > Topic Test 1 Revision > Flashcards

Topic Test 1 Revision Flashcards

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1
Q

What is a material?

A

A material describe substances that are used to make objects.

  • can be pure or mixture
  • properties of mixtures determine how they are used

Wood, paper, nylon because they can be used to house, book and clothes.

Substances that are not classified as material include chemicals such as hydrochloric acid, chlorophyll and carbon dioxide,

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2
Q

Define matter

A

Anything that has mass and occupies space.

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3
Q

Define Element

A

Elements are substances that are made up of just one type of atom.

Consists with atoms of the same atomic number (no of protons )

Pure metals such as gold or sliver
Non-metal such as carbon

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4
Q

Define compounds

A

Compounds are pure substances made up of more than one type of atom in fixed proportions and are chemically bonded.

Eg calcium carbonate - chalk, limestone, marble

Can only be broken with lost of energy (action and anion - salt)

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5
Q

Mixture

A

A mixture is a physical bonded solution of materials which can be separated from each other daily with little energy required.

Water with sand, stone, fish

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6
Q

What are the properties of metals and examples

A
  • 80% of known elements
  • 20% in the mass of earth
  • only few are naturally occurring called native metals such as copper and Gold
  • valuable due to properties being ductile, malleable, tensile strength, conductors, shiny lustre, high melting and boiling points.
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7
Q

What is an alloy

A

An alloy is a mixture of a metal with other metals or small amounts of non-metals.
- physical property demonstrated by metals and their alloys is the nature of the bonding that exits within metals.

Eg . Iron is abundant and easily workable but when it is in its pure form it is relatively soft and prone to corrosion.
If iron is allowed with carbon then the result is much stronger and corrosion-resistant (STEEL)

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8
Q

What is a Polymer

A

Greek : poly- many. Mer - parts

Polymers are materials with molecular structure that is composed of many repeating smaller units bonded together.

Eg plastics such as polyethylene, nylon, rubbers such as latex.
Natural - wool, silk, paper, cellulose
Synthetic- polystyrene

Vastly different set of physical properties when compared to metals

  • less dense
  • corrosion resistance
  • electrical assistance
  • polymers of biological nature are compatible with human tissue
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9
Q

Define ceramics

A

Ceramics are inorganic, non-metallic solids formed from a mixture of metal and non-metal elements.

metalloid element Held together by Ionic and covalent bonds
- can be ordered (crystalline) or irregular (amorphous)

Eg NATURAL - KAOLINITE for making porcelain
SYNTHETIC - SILICON used as an abrasive

Includes a wide range of elements, demonstrating a wide range of properties but in general they are hard, high compressive strength and can withstand high temps, good insulators, semiconducting and superconducting properties.

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10
Q

What is a composite material

A

Composite materials are materials made from two or more different materials with different physical and chemical properties

Eg glass and plastic make fibre glass.
Reinforced concrete (concrete matrix with embedded steel bars) - Low tensile strength of concrete (ceramic) counteracted with a high tensile Strength of steel while maintains high compressive strength of concrete.

Has a range of properties which one material cannot do alone

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11
Q

Define solution

A

A solution is a homogenous mixture of a solute dissolved in a solvent

Coffee
Sugar and water

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12
Q

Define pure substance

A

A pure substance sample of matter with both definite and constant composition and distinct chemical properties

Eg salt, sugar, tin, baking soda

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13
Q

Define homogenous

A

Uniformly distributed components of a substance distributed throughout he substance

The solute and the solvent cannot be distinguished from each other

Eg Ice and water

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14
Q

Define heterogenous

A

Diverse and different
A heterogenous substance or solution possesses two or more different types of phases in the one sample.

Milk, suspension, dirt

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15
Q

How to work out abundance?

A

Abundance % = peak height (w ruler) X 100
—————————-
Total peak height (ruler)

Total peak height is the sum of all the peak measurements

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16
Q

What is mass spectrometry

A

Mass spectrometry can be used to measure the mass of atoms or molecules.

It can determine

  • relative molecular mass and molecular structure of complex organic compounds
  • relative isotopic mass of the isotopes of an element.

It uses the function of a mass spectrometer to calculate the measurements.

It is quantitative

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17
Q

List and explain the process of mass spectrometry (IADD)

A
  1. IONISATION: the vaporised sample is bombarded with high energy electrons or ultraviolet light, leaving atom ionised with overall positive charge (knocks out electrons)
  2. ACCELERATION: The positive ions are accelerated by an electric felid so they all move at high speeds.
  3. DEFLECTION: The ions are then directed through a strong magnetic felid where they undergo deflection according to their masses. (Light ions = more deflection, heavy ions less deflection.)
  4. DETECTION: the amount of ions that strike detector and land in each position along the detector shows the abundance of ions with a specific mass. Therefore showing abundance of specific isotopes. Find the info and puts it into a mass-to-charge ratio (m/z)
  5. ) This information is then made into a graph called a MASS SPECTRUM . The graph presents the ions and their relative abundance. (Relative abundance = y axis, atomic mass = x axis)
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18
Q

What is a spectrometer

A

A spectrometer is an instrument used to determine the radiative isotopic masses of element and their isotopic abundances.

  • it separates the individual isotopes in a sample of the element
  • determines the mass of each isotope, relative to the carbon-12 standard
  • calculates the relative abundance’s of the isotopes in the
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19
Q

What is the Process of Atomic emission spectroscopy (AES=4)

A
  1. Heated element sample produces a light.
  2. The light then is directed to pass through a lens, which focuses it to a certain point.
  3. The light then goes through a prism, which splits it into separate wavelengths.
  4. The photographic plate at the back then displays the wavelengths in the form of a line emission spectrum.
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20
Q

What does Atomic Emission Spectroscopy Do?

A

Analysing light is called Spectroscopy

An emission spectroscopy has the ability to identify an element within a sample, through the wavelengths observed when emission occurs.

From the known spectra we are able to work out which element is the unknown.

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21
Q

Define quantised

A

Electrons in atoms can only be seen in certain discrete energies.
Theses energies are associated with the shells in which the electrons can be found.

The energy levels of the electrons are described as being QUANTISED.

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22
Q

Difference between ground and excited state

A

GROUND STATE is the electrons existing in their lowest possible energy state in the atom.

When absorbency of energy occurs the electrons are energised and moves to a higher energy level. This higher energy level is known as the EXCITED STATE

23
Q

Light and Electromagnetic Spectrum

A
  • ‘LIGHT’ is a part of the electromagnetic spectrum and can be divided into ‘Rainbow colours’
  • Each portion of the Electromagnetic Spectrum has specific frequencies, wavelengths and energy.
  • The range of different forms of electromagnetic radiation is referred to as the electromagnetic spectrum.
  • Eg Violet: high energy, high frequency and short wave length
    Red: low energy, low frequency and long wave length
24
Q

What is Absorbance

A

ABSORPTION is a measure of capacity of a substance to absorb light of a specified wavelength.

ABSORPTION LINE is the individual colours of light in a continuous spectrum that are absorbed by hydrogen atoms.

ABSORPTION SPECTRUM is the collected of absorption lines on a spectra.

25
Q

Explain Absorbance Spectra

A
  • electrons closer to the nucleus have the lowest energies and experiences the strongest attraction to the nucleus.
  • an electron jumps to a higher energy level if it absorbs energy that corresponds exactly to the difference in energy between the lower energy level and the higher energy level.
  • the different quantities of energy required to prompt these ground state electrons are supplied by electromagnetic radiation of varying wavelengths and frequencies, which are observed as the different colours of light.
  • qualitative
26
Q

What is Emission Spectra

A

Shortly afterwards the electron jumping to a higher energy level, it returns back to its ground lower energy state.

  • as they electron falls it emits the absorbed energy out in the form of light energy, that corresponds to exactly the difference in energy levels between the higher and lower energy shells.
  • quantitative
27
Q

What is the emission spectrum?

A

The EMISSION SPECTRUM is the collected emission lines represented of similarly to the absorbance spectrum.

The EMISSION LINES are the individual colours of light that are emitted by the particular atom.

28
Q

What is the atomic absorption spectroscopy

A

It is a method used to perform Qualitative and Quantitative analysis.

  • it finds out what element is in a sample and how much of it is present
  • can analyse more than 70 elements
  • can be used with mixtures
  • can detect small amount up to micrograms per litre
29
Q

What is the process of Atomic Absorption Spectroscopy?

A
  1. A CATHODE LAMP made up single element being tested is made.
    Eg. Testing for Zinc, means a Zinc cathode lamp is made.
  2. The sample solution is sprayed onto flame and is vaporised, atomising the substances in the sample.
  3. When light of a specific wavelength (from the cathode lamp) passes through the vaporised sample, only the element being tested will ABSORB SPECIFIC WAVELENGTHS from the lamp. This is because energy levels of all other atoms’ electron shells are different.
  4. LIGHT PASSES THROUGH FROM SAMPLE and what remains of it after absorption passes through a slit.
  1. Light then enters a MONOCHROMATOR, which detects only one wavelength for analysis by the detector
  2. The number produced when the DETECTOR measures intensity of light is called an absorbance value - measure of amount of light that passes through sample without being absorbed

7.) To measure amount of element present, absorbance value of SAMPLE IS COMPARED to that of the known samples. Then it is done by CONSTRUCTING A CALIBRATION CURVE.
It first needs to compare known concentrations of elements with their intensities, and then calibration curve of concentration against absorbance value is made.

30
Q

What is nanotechnology

A

Nano technology is a branch of materials science that investigates the design, properties and applications of materials produced on this scale.

31
Q

What is nanoscale

A

The term nanoscale refers to the structures that are between 1 and 100 nanometers across.

A nano metre is one billionth of a metre (10^9m)

32
Q

What are nano-materials

A

Nano materials are substances both natural and synthetic that are composed of single units that exist in the nano scale.

Natural: spider silk, butterfly wings, opals, bottom of geckos feet all have nano structures

33
Q

What is a fullerene

A

Fullerenes are naturally occurring Nano materials

Fullerenes are 3D structures formed by networks of carbon atoms.

The three structures which it Exhibits is the
- Carbon nano tube ; a very strong and stiff network in the shape of a cylindrical tube. It is used as a reinforcement in composite materials used in super conductors.

  • Graphene ; flat 2D layers of carbon arranged in the form of hexagons
  • Bucky ball; in the shape of a soccer ball
34
Q

Examples of Composite nano materials

A

Nano materials Small size and unique structural properties make them useful for developing composite materials. Which include

  • Stain resistant cotton ; cotton fibres are covered with water-resistant nanoparticles so that liquids can not penetrate the material.
    This makes the fabric water and stain resistant Eg Silic Shirts
  • Tyres; added carbon (25%) improved resistant and abrasion. It increases electrical conductivity and prevents the build up of static electricity for fuel trucks.
35
Q

How to make Nano particles

A

Top down fabrication: is the Grinding down of a larger scale of material than desired by selectively removing or progressively reducing the material until required size and shape is achieved. (ZnO,TiO2)

Benefits - uniformity
Negative - limited to structures as limits to tool usage

laser ablation (carbon nano tubes );

  • vaporise graphite
  • reassemble as CNT on a cooled surface
Solution evaporation
•Chemical vapour deposition
•Microbial synthesis
•Chemical precipitation
Perhaps able to shift one at atom at time with atomic force microscope?
36
Q

What is nano particles used for

A

Very large surface area to the volume they occupy.
•The large surface area of nanoparticles is important in three ways.
•Adsorption
•Transportation
•Catalyst

37
Q

Explain the three ways nanoparticles are used for

A

Adsorption of molecules:
a molecule sticks to a surface of a solid or liquid. (geckos)
•different from absorption, where molecules are incorporated into the substance like a sponge and water
•large SA means that even a small volume of nanoparticles can adsorb a large number of molecules
•can be used to remove unwanted chemicals and gases (silica and carbon)

2 Transportation of molecules:
•transport the molecules that are adsorbed
•small size and large surface area mean that they can transport chemicals through air, skin and even cells
•variety of applications in medicine for transporting drugs into the body
•already being used in some chemotherapy treatments for cancer.

3 Catalysts:
•can also be used to increase the rate of particular chemical reactions.
•described as acting as catalysts because they speed up the reaction but are not consumed (used up) by the reaction.
•reactant molecules adsorb onto the surface of the nanoparticles, which allows reactant molecules to combine to form the product.
•large surface area of nanoparticles means that many of these reactions can take place at the same time,
•increases the rate of the reaction significantly

38
Q

What are the properties of nanoparticles

A

physical, chemical and optical properties can change.
•When gold is in the form of nanoparticles, it loses its metallic luster
•can take on a variety of colours depending on the size of the gold particles

39
Q

How is nano technology used in medicine

A

Colloidal Gold
•Used for labeling antigens
•Optimise distribution of unstable drugs to tissues and cells, in difficult sites like the brain, retina, tumours
•target tumors and provide detection
Silver
•Antibacterial and anti fungal properties
•Due to release of Ag+ from surface of metal
•As nanoparticle, SA enhances antibacterial effectiveness.
•Bandages, instruments, masks, socks, toys cosmetics.

40
Q

How is nanaotechnolgy used in zinc

A

Zinc oxide, ZnO,
•commonly used in sunscreens.
•Zinc oxide absorbs a broad range of the UV spectrum and so provides excellent protection from the Sun.
•sunscreens that contain metal oxides are milky white when applied to the skin.
•zinc oxide nanoparticles produces a sunscreen that is clear, and therefore is preferred by beach-goers

41
Q

How is nano particle used in sunscreen

A

CSIRO investigating zinc oxide nanoparticles used in sunscreens
•whether or not these nanoparticles can penetrate the skin,
•Their long-term health effects unknown
•how the particles might impact the environment: unkown
•Initial studies: small amounts of zinc oxide from sunscreens are absorbed can be detected in the blood and urine
•not clear yet if the absorbed zinc oxide has any negative effects on the human body.
•The most recent research indicates that the cells of the immune system can break down the nanoparticles.

42
Q

Are nano particles safe

A

air and into our bloodstream
•through skin and even into cells.
•may interact with biomolecules to cause unwanted chemical reactions
•potentially dangerous if breathed in or applied to the skin (e.g. in sunscreen, fabrics or cosmetics).
•Asbestos?

43
Q

Explain separation by particle size (sieving and filtration)

A

One of the simplest separation techniques is to separate the substances based upon their particle size.

Sieving - separates a mixture of solids with different particles sizes by passing the solids through a mesh siv.
- used in baking (flour and baking soda), mining industry (sieving the drift away from previous ore)

Filtration - is used to separate solid particles from a liquid or a gas.
Eg. Air filters, vacuum cleaners, extraction fans or industrial chimneys separate particles from the air.

Gravitational filtration - uses the weight of the solid-liquid mixture to push the mixture through filter paper. The liquid passes through the filter paper solid stays on top. Filtrate is the pure liquid while the residue is what is on the filter paper.

Vacuum filtration - faster than gravitational filtration.

44
Q

Explain separation by density

A

Density is a measure if the mass per unit of volume of a substance. The difference in density between substances in a solid liquid mixture determines whether or not if it will sink or float.

Separation funnels - used to separate fragrance
- if two densities in a mixture immiscible then the liquids can be separated with a separation funnel. In a flask the mixture make two layers (less dense floats) (more dense sinks), by opening the tap the liquid flows into the beaker, close the tap when the one with the higher density is completing in the beaker.

45
Q

Separation by boiling point (evaporation, distillation, fractional distillation)

A

Breakdown under heating, separation can be based in the difference in boiling points.

Evaporation - when to separate the dissolved solute from the solvent, the solvent needs to be boiled off in order to recover solid solute.

Distillation uses the principle of evaporation but applies to liquids. The solution is heated in the flask to vaporise the liquid. The vapour passes through the condenser and cools down the vapour making go back to liquid form of droplets and goes along the condenser until falling into receiving flask. Liquid collected is distillate. The boiling point of each liquids need to be approx 50° difference.

Fractional distillation: used for petrol. More than 2 liquids in a solution, more precise and does not need 50° boiling points between liquids.
It has the same process as a distillation but it has an extra part called the fractioning column which is placed between the flask with mixture and the condenser which allows increased contact between rising vapour and falling condensate.

46
Q

Separation by electric charge (magnetic and electro static)

A

Magnetic uses the negative and positive polar charges to attract certain materials away from the mixture

Electrostatic attraction - opposite electric charges attract each other, the force of attraction between opposite charges known as electrostatic charge can be sued to separate particles from uncharged particles.

47
Q

What is core charge

A

Core charge remains constant in groups because the valence electrons are held together weakly because they are further from nucleus thus electrostatic attraction is weaker.
Increases across periods because more strongly held together even though the same distance between nucleus and valence electrons still remain, the higher core charge from nucleus experiences a higher electrostatic attraction.

Core charge is equal to the number of protons - the total inner shell electrons

Core charge is the attractive force of the nucleus of an atom on the valence electrons.

Constant down group and increase across period

48
Q

What is atomic radius

A

Atomic radius is the measurement used for the size of the atom
* distance from the nucleus and the valence electrons

Increase down the group because core charge is constant but the number of shells increase thus the radius is increases, decrease across period because core charge is strong bringing in closely the electrons and the occupied shells are constant

49
Q

What is ionisation of energy

A

Increase across period because core charge is stronger thus valence electrons are more attracted to the nucleus thus more energy is needed to get rid of the electron , decrease across group core charge is not as strong and is further away from nucleus thus less energy needed

Ionisation is the process of removal of an electron

Ionisation energy is the energy required to remove one electron from an atom of an element in gas phase

First ionisation energy is the energy required to remove the first Valence electron from an atom in the gas phase

Successive ionisation energies are the energies required to remove multiple electrons consecutively from an atom of an element in gas phase

50
Q

What is metallic character

A

Decreases in groups, increase in periods

Metallic character is how closely an element exhibits the properties commonly associated with metals, and how easily loses an electron to be a cation.

51
Q

What is electronegativity

A

Down group decreases because core charge is constant but shells increase thus less attracted to nucleus
Across period increased because number of occupied shells constant but core charge increases across period, valence electrons are more strong attracted to nucleus.

Electronegativity is the ability of an atom to attract electrons in a covalent bond towards its self.

52
Q

How to calculate relative atomic mass

A

Relative atomic mass x relative isotopic mass
—————————-
100

52
Q

Calculating Relative isotopic abundance

A

Ar (relative atomic mass) = (% x relative isotopic mass) +(…)
——————————————
100

Or - length of line divide total on y axis then times by 100

53
Q

Calculate the abundance of isotopes from relative atomic masses and isotopic masses

A

Ar = (% x unknown lighter isotope);+ (% x (100-unknown larger isotope) ) / 100

Then expand

Work out for a - smaller isotope
100-a is larger isotopic

Year 11 Chemistry Atar (3 decks)

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