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8/11/2019 No Whines on Chemistry Information Booklet
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No Whines On ChemistrySecondary 2
Independent Studies Team
Elements, Compounds and Mixtures
Information Booklet
Solutions and Suspensions
Separation Techniques
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Elements, Compounds and Mixtures 2
Elements
2
Periodic Table of Elements
2
Metals vs Non-Metals 3
Common Elements
3
Electronic Configuration + Valence Electrons (Further Learning) 9
Particles of Matter 10
Compounds
11
Mixtures
12Separation Techniques 16
Chemical Changes
16
Physical Changes 16
Physical Separation Techniques 16
1INFORMATION BOOKLET - NO WHINES ON CHEMISTRY TEAM
Table of Contents
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Elements, Compounds and Mixtures
Elements
An element is a substance which cannot be broken down in to two or more
substances by chemical methods. It is:
Simplest kind of matter
Classified into the periodic table of elements.
Periodic Table of Elements
Elements are classified systemically into the periodic table of elements based
on properties. Each element has:
a symbol of 1 to 3 letters
an atomic number and nucleon number
Horizontal Row: Period
Vertical Row: Group
As one moves across a period from left to right, the properties of the elements
will change gradually from metallic to non-metallic.
Elements in the same group have similar chemical properties and will undergo
the same types of chemical reactions.
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Metals vs Non-Metals
Common Elements
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Copper (Atomic Number: 29, Atomic Mass: 64, Symbol: Cu, Period 4) Appearance
Shiny Reddish Brown Solid
Properties
High Melting and Boiling Point
Good Conductor of Electricity Ductile (Easily Drawn into Wires)
Malleable
Uses
Commonly used to make electrical wires
Used to make water pipes
Copper + Tin => Bronze (Alloy, Mixture)
Copper + Zinc => Brass (Alloy, Mixture)
Aluminium (Atomic Number: 13, Atomic Mass: 27, Symbol: Al, Period 3,
Group 3) Appearance
Shiny Solid
Properties
Strong and light
High Melting and Boiling Point
Good Electricity Conductor
Malleable (Can be shaped)
Uses
Make aeroplane parts (Strong and Low Density)
Make drink cans, cooking utensils and ladders
Overhead Electricity Cables
Chlorine (Atomic Number: 17, Atomic Mass: 35.5, Symbol: Cl, Period 3,
Group 7) Appearance
Greenish-Yellow Gas
Properties
Low Melting and Boiling Point
Poor Electrical Conductor
Uses
Used in bleaches for clothes
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Iodine (Atomic Number: 53, Atomic Mass: 127, Symbol: I, Period 5, Group
7) Appearance
Black Crystal
Properties
Low Melting and Boiling Point Poor Electrical Conductor
Brittle
Sublimes when heated to form a violet vapour
Uses
Used as an antiseptic in medicines (Dissolves in Ethanol)
Oxygen (Atomic Number: 8, Atomic Mass: 16, Symbol: O, Period 2, Group
6)
Appearance Colourless Gas
Properties
Low Melting and Boiling Point
Poor Electrical Conductor
Uses
Used for respiration in living things
Magnesium (Atomic Number: 12, Atomic Mass: 24, Symbol: Mg, Period 3,
Group 2) Appearance
Grey Solid
Properties
High Melting and Boiling Point
Good Conductor of Electricity
Malleable
Burns with a dazzling white light
Uses
Used to make milk of magnesia (Relieve acid of indigestion) Used in distress flares (Burns with a white dazzling light)
Used in making fireworks
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Iron (Atomic Number: 26, Atomic Mass: 56, Symbol: Fe, Period 4) Appearance
Grey Solid
Properties
High Melting and Boiling Point
Good Conductor of Electricity Ductile
Malleable
Uses
Make Cutlery
Carbon (Atomic Number: 6, Atomic Mass: 12, Symbol: C, Period 2, Group
4) Appearance
Exists in different forms (Allotropes): Diamond, Graphite, Soot, Charcoal) Graphite is a black solid
Diamond is the hardest known substance.
Properties
Diamond can be polished to form a shiny, reflective and transparent solid.
Graphite is very lightweight
Uses
Graphite can be used for pencil leads
Charcoal is used for fuel
Diamond is used for making drills to cut through hard metals.
Nitrogen (Atomic Number: 7, Atomic Mass: 14, Symbol: N, Period 2, Group
5) Appearance
Colourless Gas
Properties
Unreactive Element at Room Temperature
Does not burn or support combustion
Low Boiling Point
Uses
Packing of Food
Fertilisers
Freezing Agent for Food
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Sulfur (Atomic Number: 16, Atomic Mass: 32, Symbol: S, Period 3, Group 6) Appearance
Yellow Powdery Solid
Properties
Poisonous
Soluble in Organic Solvent like alcohol but not water Uses
Drugs
Sulfuric Acid
Harden Rubber in the process of making tyres (Vulcanization)
Zinc (Atomic Number: 30, Atomic Mass: 65, Symbol: Zn, Period 4) Appearance
Grey Solid
Properties Good Conductor of Electricity
Strong and Corrosion Resistant
Uses
Coat Iron Sheets (Galvanised Iron)
Produce Electricity in Batteries
Galvanize Metal Gates
Zinc + Copper => Brass
Sodium (Atomic Number: 11, Atomic Mass: 23, Symbol: Na, Period 3) Appearance
Silvery Solid
Properties
Malleable and Ductile
Good Conductor of Heat and Electricity
Soft
Reacts Violently with Water
Burns with a Brilliant Golden-Yellowish Flame
Uses
Table Salt
Street Lamps
Manufacturing Glass, Pottery and Soap
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Fluorine (Atomic Number: 9, Atomic Mass: 19, Symbol: F, Period 2) Appearance
Pale Yellow/White/Colourless Gas
Properties
High Poisonous
Heat Resistant Pungent Odour
Highly Reactive with all the elements except for Noble Gases
Uses
Toothpaste
Refrigeration
Uranium Hexafluoride for Nuclear Power Industry
Phosphorus (Atomic Number: 15, Atomic Mass: 31, Symbol: P, Period 3) Appearance
White / Red / Black Solid
Properties
Waxy
White Phosphorus glows in the dark and is poisonous
Black Phosphorus is made under high pressure and conducts
Red Phosphorus cannot dissolve in many liquids
Uses
Insoluble and Inert coating to many metals
Fire starters and stoppers
Fertiliser
Glows in the dark
Boron (Atomic Number: 5, Atomic Mass: 11, Symbol: B, Period 2) Appearance
Brown Powder (Amorphous Boron)
Hard, brittle, lustrous black semimetal. (Crystalline Boron)
Properties
Poor electrical conductor at room temperature, but good electrical conductor at
high temperatures. Crystalline form less reactive than amorphous form.
Oxidised slowly in air at room temperature and ignites spontaneously at high
temperatures. (Amorphous)
Uses
Glass and ceramics
Fertiliser
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Electronic Configuration + Valence Electrons (Further Learning)
Atoms are made up of subatomic particles, mainly protons, neutrons and
electrons.
An electronic configuration is written as follows:
X.X.X
For example,
Boron -> 5 electrons -> 2 electron shells -> electronic configuration = 2.3
Calcium -> 20 electrons -> 4 electron shells -> electronic configuration = 2.8.8.2
Note:
Number of periods = Number of occupied electron shells
Number between each period = Number of electrons on that particular shell
Chlorine -> 17 electrons -> 3 electron shells -> 2.8.7
Chlorine has 3 electron shells -> 3 periods
Chlorine has 2 electrons on 1st shell, 8 electrons on 2nd shell, 7 electrons on
3rd shell.
Valence ShellThe valence shell is the furthest occupied shell from the nucleus. Valence
electrons refer to the electrons in the valence shell.
(only valence electrons are involved in chemicalreactions)
Examples of Borons electronic structure:
Summary of Shells1. Number of period = Number of occupied electronic shells
2. Number between each period = Number of electrons on that particular shell.
Chlorine => 17 electrons > 3 electron shells > 2.87
Chlorine has 3 electron shells > 3 periods
Chlorine has 2 electrons on 1stshell, 8 electrons on 2ndshell, 7 electrons on 3rd
shell
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Particles of Matter
A Scanning Tunneling Microscope is used to see particles of matter.
There are different types of particles:
Atoms
Molecules
Ions and Isotopes (Sec 2)
Atoms Smallest Particle of Any Element
Diameter of about 0.1 * 10-9metre
Can have the chemical properties of the elements
Each element consists of particular types of atoms.
Atoms of different elements are different.
Molecules Group of 2 or more atoms held together by chemical bonds
May consist of atoms of a single element (O2), or of different elements (H2O)
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Compounds
A compound is a substance containing 2 or more elements chemically
combined together.
Properties of Compounds Compounds are formed by chemical reactions. Their formation usually involves an
exchange of energy in the form of heat, light or both with the surroundings.
Properties of the compound formed have different properties from the constituent
elements.
Compounds cannot be broken down by physical methods.
Compounds can only be broken down by chemical methods which involve heating or
lighting or electric current.
Different elements in a compound are joined together in a fixed proportion by mass (and
number of atoms)
How are compounds formed? Combination An example is combustion
occurs when elements or compounds burn and combine with oxygen to form one
or more new compounds
Example of Combustion: Carbon(Element) + Oxygen(Element) => Carbon Dioxide
(Compound) / Sodium(Element) + Water (Compound) => Sodium Hydroxide
(Compound) + Hydrogen (Element)
Decomposition
Complex compounds heated to be broken down into simpler compounds. Sugar
(Compound) => Water Vapour (Compound) + Carbon (Element)
If something has no chemical formula, it is a mixture.
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Mixtures
A mixture consists of two or more different substances that are mixed but not
chemically joined together.
Do not have chemically symbol or formula
Can be solids (salt and sand, metal alloys, etc.)
liquids (mineral water, milk, etc.)
gases (air)
Examples: air, mineral water, bronze, steel, brass
Two types of mixtures:
Solutions
Suspensions
Solutions Consists of 2 parts:
Solvent (the substance the solute dissolves in and forms the solution)
Solute (the substance that dissolves in the solvent of the solution)
Example:
air > nitrogen (solvent) + oxygen, carbon dioxide and etc (solute)
saltwater > water (solvent) + salt (solute)
bronze > tin (solvent) + copper (solute)
Homogenous colour, density, appearance and other physical and chemical properties
are the same in every part of the solution
Light passes through the solution (solute particles are spread evenly and thus too small to
reflect or block any light passing through)
Three types of solution:
Dilute solution small amount of solute in large amount of solvent
Concentrated solution large amount of solute dissolved in solvent
Saturated solution maximum amount of solute dissolved in solvent
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SolubilityThe solubility of a substance is the maximum quantity of that substance which can dissolve
in 100 grams of the solvent a given temperature.
Eg: Copper (II) Sulfate has a solubility of 32 grams per 100 grams of water at 20 degrees
celsius.
Factors affecting solubility Type of solute
The type of solute affects solubility as different substances have different solubilities in the
same solvent.
Type of solvent
The type of solvent also affects solubility as the same substance have different solubilities in
different solvents.
TemperatureThe solubility of solids and liquids increases with the increase in temperature whereas the
solubility of gases decreases as the temperature increases.
Pressure
The solubility of gases increases with the increase in pressure whereas the solubility of solids
and liquids decreases as pressure increases. However, the effect of pressure on solubility of
solids and liquids is typically weak.
Solubility Graph
The left is a solubility graph,
which shows how the solubility
of different substances in a
solvent varies with various
factors. In this case, the
solubility graph shows the
changes in solubility ofcompounds in water with
temperature.
[Image from: http://www.sciencegeek.net/Chemistry/taters/graphics/solubility.gif]
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Rate of dissolving
Rate of dissolving is the time taken for the dissolving process from the time the
solute was added to the solvent until it is completely dissolved.
Factors affecting rate of dissolving
Temperature of solvent
The temperature of the solvent affects the rate of dissolving by speeding up the process. The
particles of the solvent and solute are able to move faster in a higher temperature which
results in them mixing together more quickly. Hence, the process of dissolving in faster.
Size of solute particles
The smaller the size of the solute particles, the larger the exposed surface area of the solute
particles. Dissolving always occurs on the surface of the solute. Hence, solute particles can
dissolve faster with more exposed surface area if they are smaller. This increases the rate of
dissolving.
Agitation of the solution
By stirring or shaking the solution, it remove the solvent that has already dissolved pieces of
the solute and replaces it with fresh solvent.
*Note: Rate of dissolving is not the same as solubility.
Rate of dissolving is how fast the solute dissolves in the solvent entirely whereas solubility is
the maximum amount of solute which can dissolve in 100 grams of solvent at a particular
temperature.
SuspensionsSuspensions are formed when the substance does not dissolve in the solvent or when the
amount of substance in the mixture is over its solubility limit.
Examples:
sand in water
muddy water concrete
Properties:
Heterogeneous insoluble particles settle at the bottom so physical and chemical
properties are unequal throughout suspension.
Light does not pass through the suspension. (insoluble particles are big enough to
block incoming light)
Particles settle to the bottom after suspension is left to stand for a while.
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Solutions vs Suspensions
Compounds vs Mixtures
A single compound has a fixed boiling point. A mixture of compounds have a range of boiling
points.
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Separation Techniques
Chemical Changes
Chemical Change:
New substance formed Different properties (Different melting points / chemical reactions)
New substance have different appearances
A lot of heat given out in chemical change.
Chemical Reactions:
Combustion
Decomposition
Physical Changes
Physical Change:
No new substances formed.
Changes easily reversed through physical separation techniques
Example: Dissolving of salt in water
Physical Separation Techniques
Filtration
Filtration is one of the techniques used to separate mixtures. A mixture of solid and liquid is
poured into a filter funnel and passed through a filter paper. The filter paper is usually folded
into a cone shape to fit into the filter funnel. When the mixture passes through the filter paper,
the extremely tiny holes in it allow the liquid to flow through and traps the solid particles. The
solid trapped in the filter paper is known as the residue whereas the liquid that passes
through the filter paper is known as the filtrate. However, this method will only be viable if the
solid is insoluble in the liquid.
Crystallisation
When a solid dissolves in liquid, it forms a solution and thus filtration is unable to separate.
Hence, other methods like crystallisation are used. When the solution is heated, most of the
solvent is evaporated off until the solution becomes saturated. The solution is then left to
cool, causing its solubility to decrease, resulting in the dissolved solid to appear as pure
crystals. The cooled solution is then poured away to obtain the crystals, which are dried by
pressing them between sheets of filter paper.
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Evaporation to dryness
Evaporation to dryness is an alternative to crystallisation. This method is slightly different from
crystallisation. The solution is heated until all the solvent is evaporated to leave behind only
the solute instead of heating the solution until it is saturated before cooling it to obtain the
crystallised solute. However, there are downfalls to evaporation to dryness as compared to
crystallisation. Evaporation to dryness cannot be used for sugar solution as sugar will
decompose to give water and carbon when heated.
Distillation vs Fractional distillation
Distillation is used to purify liquids. In The liquid is boiled and turns into gas, which is pure as
the other substances are left in the solution. The gas is then cooled and condenses to a pure
liquid which is called a distillate. This method is used to obtain a pure solvent from a solution.
An example is the distillation of seawater to obtain pure water. The seawater is boiled in a
flask and the steam is then cooled in a condenser and condenses. The pure water droplets
are then collected in a conical flask whereas the salt and other impurities remain in the flask.
However, if there is a solution of miscible liquids, then fractional distillation is used. The
difference between the two methods is the fractionating column, which separates the liquids
according to their boiling point. The lowest boiling point liquid is distilled first, allowing the
miscible liquids to be separated. However, the liquids in the solution must have different
boiling points for fractional distillation to work. For example, in a mixture of ethanol and water,
as ethanol has a lower boiling point at 78 degrees celsius, it boils and then condenses first,
leaving the water in the flask as it has a higher boiling point at 100 degrees celsius.
Separating FunnelFor non-miscible liquids, a separating funnel is used. The lighter liquid forms a separate layer
above the heavier liquid. The tap is opened so the lower liquid layer runs out first and is
collected in a beaker. The tap is quickly closed as the last drops of the liquid flows into the
beaker. Then, the tap is opened for the higher liquid layer to run out into another beaker. An
example is a mixture of water and petrol, where the water is let out and collected in beaker
before the petrol as the former is heavier than the latter.
Magnetic attraction
Magnetic attraction is used to separate magnetic substances from non-magnetic ones in amixture. Electromagnets are used to remove scrap steel and iron plus other metallic waste at
junkyards. Electromagnets are used as they are temporary magnets so they can be
activated and deactivated at the appropriate times.
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Chromatography
Chromatography is used to separate a mixture into all of its various components and identify
them. There are many types of chromatography, one of them being paper chromatography. It
can be used to separate and identify dyes in black ink. Two pencil lines are drawn on a piece
of paper and a drop of black ink and other drops of coloured dye are placed on one of the
pencil lines. The paper is usually placed in a beaker of suitable solvent, in this case butanol,
ethanoic acid and water, with the pencil line just touching the solvent. The solvent travels up
the paper and splits the black ink into its different components. The paper is removed when
the paper reaches the other pencil line and then dried. Identical dyes travel the same
distance up the paper and the unknown ones can be inferred from the known ones.
Chromatography is applied in forensic science and used to ensure high food quality by
testing the purity of substances.
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