Information Booklet Elements Compounds and Mixtures

8/12/2019 Information Booklet Elements Compounds and Mixtures

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Table of Contents

1. Elements, Compounds and Mixtures

a. Elements (Page 1)

b. Introduction to the Periodic Table of Elements

(Page 1)

c. Metals vs Non-Metals: Difference in Properties

(Page 2)

d. List of Common Elements (Page 2)

e. In-depth Details of Common Elements

(Page 3)

f. Further Learning

(Page 15)

g. Particles of Matter (Page 16)

h. Atoms (Page 16)

i. Molecules

(Page 16)

j. Compounds (Page 17)

k. Mixtures (Page 18)

l. Compounds vs Mixtures (Page 22)


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2. Solutions and Suspensions

a. Solutions (Page 18)

b. Solubility (Page 19)

c. Rate of Dissolving (Page 20)

d. Suspensions (Page 21)

e. Solutions vs Suspensions (Page 21)

3. Separation Techniques

a. Physical Change

(Page 23)

b. Chemical Change (Page 23)

c. Physical Separation Techniques

(Page 23)


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Elements, Compounds & Mixtures

Elements

An element is a substance which cannot be broken down into two or more

simpler substances by chemical methods.

Simplest kind of matter

Classified into the periodic table of elements

Periodic Table of Elements:

Elements classified systematically into the periodic table based on

properties.

Each element has a symbol of 1 to 3 letters.

Each element has an atomic number and nucleon number.

Horizontal Row : Period

Vertical Row: Group

As you move 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

Properties Metals Non-Metals

Appearance Shiny Dull

Electrical and Heat

Conductivity

Good Conductors of

Electricity and Heat

Poor Conductors of

Electricity and Heat

Melting and Boiling

Points

Generally High (Except

Mercury)

Generally Low

Ductility and

Malleability

Malleable and Ductile Brittle

Density Generally High Generally Low

Sound when hit Sonorous Non-sonorous

Common Elements

Copper Cu Zinc Zn

Aluminium Al Mercury Hg

Chlorine Cl Helium He

Iodine I Neon Ne

Oxygen O Hydrogen H

Magnesium Mg Calcium Ca

Iron Fe Sodium Na

Carbon C Fluorine F


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Nitrogen N Phosphorus P

Sulfur S Boron B


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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


Good electricity conductor

Malleable (Can be shaped)


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Uses

Make aeroplane parts (Strong and low density)

Make drink cans, cooking utensils and ladders

Overhead electricity cables


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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

Iodine (Atomic Number: 53, Atomic Mass: 127, Symbol: I, Period 5, Group

7)

Appearance

Black crystals

Properties



Brittle

Sublimes when heated to form a violet vapor

Uses

. Used as an antiseptic in medicines (Dissolves in ethanol)


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Oxygen (Atomic Number: 8, Atomic Mass: 16, Symbol: O, Period 2, Group 6)

Appearance

Colourless gas

Properties



Uses

Used for respiration in living things


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Magnesium (Atomic Number: 12, Atomic Mass: 24, Symbol: Mg, Period 3, Group

2)

Appearance

Grey solid

Properties



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

Iron (Atomic Number: 26, Atomic Mass: 56, Symbol: Fe, Period 4)

Appearance

Grey solid

Properties



Ductile

Malleable


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Uses

Make cutlery


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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


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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


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Mercury (Atomic Number: 12, Atomic Mass: 24, Symbol: Mg, Period 3)

Appearance

. Silvery liquid

Properties

Only metallic element that is a liquid at room temperature

. Unreactive

. Gives out light (Fluorescent)

. Good conductor of heat and expands evenly with it

Uses

. Thermometers

. Blood pressure measurements

. Fluorescent lamps

. Dental fillings

Helium(Atomic Number: 2, Atomic Mass: 4, Symbol: He, Period 1)

Appearance

. Colourless and odourless

Properties

. Exist as a single atom

. Noble gas

Uses

. Fill airships and balloons to gain lift


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. Condense hydrogen and oxygen to make rocket fuel


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Neon (Atomic Number: 10, Atomic Mass: 20, Symbol: Ne, Period 2)

Appearance

. Colourless and odourless under standard conditions

. Glows reddish-orange in a vacuum discharge tube

Properties

. Exist as a single atom

. Noble gas

Uses

. Neon advertising signs

. Lightning arresters to shield electrical equipment from lightning

. Aircraft beacons

Hydrogen (Atomic Number:1, Atomic Mass: 1, Symbol: H, Period 1)

Appearance

. Colourless and odourless gas

Properties

. Lowest density

. Explosive

Uses

. Fill weather balloons and blimps

. Hydrogenated vegetable oils

. Reducing agent (Eg: Treat and purify mined tungsten)


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Calcium (Atomic Number: 20, Atomic Mass: 40, Symbol: Ca, Period 3)

Appearance

. Silvery-white solid

Properties

. Relatively soft

. Ductile and malleable

. Highly reactive with acids

Uses

. Cements and mortars

. Cheese

. Help to keep bones strong and healthy

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


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. Burns with a brilliant golden-yellowish flame

Uses

. Table salt

. Street lamps

. Manufacturing glass, pottery and soap

Fluorine (Atomic Number: 9, Atomic Mass: 19, Symbol: F, Period 2)

Appearance

. Pale yellow/ white/ colourless gas

Properties

. Highly poisonous

. Heat resistant

. Pungent odour

. Highly reactive with all 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


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Properties

. Waxy

. White phosphorus glows in the dark and is poisonous

. Black phosphorus is made under high pressure and conducts electricity

. Red phosphorus cannot dissolve in many liquids

. Glows in the dark

Uses

. Insoluble and inert coating to many metals

. Fire starters and stoppers

. Fertiliser

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

. Oxidized slowly in air at room temperature and ignites spontaneously at


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high temperatures to form an oxide. (Amorphous)

. Oxidized only very slowly, even at higher temperatures (Crystalline)

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.

The centre of an atom is called the nucleus which contains the protons and

neutrons. The electrons in an atom are arranged in shells at different distances

from the nucleus.

1stshell 2 electrons

2ndshell 8 electrons

3rd shell 8 electrons (1st20 elements), 18 electrons (start to add in transition

metals)

4thshell 18 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

However, after calcium is scandium, which is a transition metal. When this series

start, the electrons start to fill up the 3rdshell instead. Therefore, scandium has an

electronic configuration of 2.8.9.2 with 21 electrons. This process will continue

until 18 electrons are filled up, which will be until zinc (2.8.18.2) and the electrons

will add normally after that.

Valence Shell:

The valence shell is the furthest occupied shell from the nucleus. Valence


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electron refers to the electrons in the valence shell. (only valence electrons are

involved in chemical reactions).

Example of Borons electronic structure:

Summary of Shells:

1. Number of periods = Number of occupied electron shells

2. 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


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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 metre

Can have the chemical properties of the elements

Each element consists of particular types of atoms.

Atoms of different elements are different

Molecules

Group of2 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)/


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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 chemical 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 two parts:

. Solvent (the substance the solute dissolves in and forms the

bulk of the solution )

. Solute (the substance that dissolves in the solvent of the

solution)

. Eg: airnitrogen (solvent) + oxygen, carbon dioxide and etc

(solute)

saltwaterwater(solvent) + salt(solute)

bronze tin (solvent) + copper (solute)


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- 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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Solubility

The solubility of a substance is the maximum quantity of that substance which

can dissolve in 100 grams of the solvent at a given temperature.

Eg: Copper (II) sulfate has a solubility of 32 grams per 100 grams of water at 20

degrees celsius.

What are the 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.

- Temperature

The 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.

What is a solubility graph?


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The above 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 of compounds in water with temperature.

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.

What are the 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 them mixing together more quickly. Hence, the

process of dissolving is 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.


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-Agitation of the solution

By stirring or shaking the solution, stirring or shaking the solution removes 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.


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Suspensions

- Formedwhen substance doesnot dissolve in solvent or when the

amount of substance in the mixture is over its solubility limit.

Examples:

o sand in water

o muddy water

o concrete

- Heterogeneous- insoluble particles settle at the bottom so physicaland 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

Solutions Vs Suspension

Solutions Vs Suspensions

Passes through filter

paper completely

Vs Solvent/liquid passes

through the filter paper

and the solute/solid isleft behind

Solute particles spread

evenly when left to settle

Vs Solute particles sink to

the bottom when left to

settle


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Homogenous Vs Non-homogenous

Light can pass through Vs Light cannot pass

through


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Compounds V.S. Mixtures

A single compound has a fixed boiling point, A mixture of compounds have a

range of boiling points.

Elements / Compounds VS Mixtures

Pure VS Impure

Fixed melting and boiling

point

VS Melts or boils over a range of

temperatures


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Separation Techniques

Chemical Changes

Chemical Change:

- New Substance Formed

- Different properties (Different melting points/chemical reactions)

- New substance have different appearance

- 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


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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.

- 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


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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 Funnel

For 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.


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- Magnetic attraction

Magnetic attraction is used to separate magnetic substances from non-magnetic

ones in a mixture. 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.

- 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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Information Booklet Elements Compounds and Mixtures

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