GCSE Topic 1 - Elements, Compounds & Mixtures Flashcards
Definition of an element
An element is a substance that consists of only one type of element. Elements cannot be broken down into simpler substances by chemical means
Definition of a compound
A compound is a substance which consists of 2 or more different elements chemically bonded together
Definition of a mixture
A mixture consists of 2 or more substances that are usually easy to separate
Is aluminium an element, compound or mixture
Element
Is sodium chloride (salt) an element, compound or mixture
Compound
Is carbon dioxide an element, compound or mixture
Compound
Is lead an element, compound or mixture
Element
Is rock salt an element, compound or mixture
Mixture
Is sugar solution an element, compound or mixture
Mixture
Is oxygen an element, compound or mixture
Element
Is sulfur an element, compound or mixture
Element
Is ethanol an element, compound or mixture
Compound
Is copper an element, compound or mixture
Element
Is air an element, compound or mixture
Mixture
Is calcium carbonate an element, compound or mixture
Compound
Is methane an element, compound or mixture
Compound
Is iron an element, compound or mixture
Element
Is silicon dioxide an element, compound or mixture
Compound
Separate the following substances into elements, compounds and mixtures:
Copper, marble chips, milk, baking soda, oxygen, sugar, carbonated water, air, sulfur, salt, alumina, Diet Coke, carbon dioxide and sea water
Elements - copper, oxygen, sulfur
Compounds - carbon dioxide, sugar, baking soda, salt, alumina, marble chips
Mixtures - air, Diet Coke, sea water, milk, carbonated water
Find suitable scientific words to complete the following sentences:
An element is a substance which………be broken down into simpler substances
Cannot
Find suitable scientific words to complete the following sentences:
Everything in the universe is made up of……..
Atoms/elements
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About….elements occur in nature
100
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Most of the crust of the earth is made up of five elements; oxygen………aluminium, iron and calcium
Silicon
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Elements are classified as…….and non-metals
Metals
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Metals usually……..electricity; they are……./…….and strong
Conduct
Hard/shiny
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Non metals are electrical……….they are dull and……….
Insulators
Brittle
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A compound is a substance made of two or more different elements………….
Chemically bonded
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Compounds have……..properties from the elements from which they are made
Different
Daltons atomic……..suggests that everything is made of minute particles called atoms
Theory
Find suitable scientific words to complete the following sentences:
All the atoms of an element are the….
Same
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The atoms of one element are not the same as the atoms of another element because they differ in……………..
The number of protons
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Small groups of atoms joined together are called………..
Molecules
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One of the elements which consist of molecules is………
Oxygen
State whether you think the following are mixtures or compound: Milk Ice Orange juice Air Paint
Milk - mixture Ice - compound Orange juice - mixture Air - mixture Paint - mixture
The formula of 5 substances are listed below, state whether it’s an element or compound and name the elements it contains:
a) CH4 (small 4 ~ slightly below letters)
b) CaCO3 (small 3 ~ slightly below letters)
c) MgS
d) H2 (small 2 ~ slightly below letters)
e) CuSO4 (small 4 ~ slightly below letters)
A) compound and the elements it contains are carbon and hydrogen
B) compound and the elements it contains are calcium, carbon and oxygen
C) compound and the elements it contains are magnesium and sulfur
D) an element - hydrogen
E) compound and the elements it contains are copper, sulfur and oxygen
The formula of 5 substances are listed below, state whether it’s an element or compound and name the elements it contains:
F) Fe
G) AlCl3 (small 3 ~ slightly below letters)
H) HBr
I) Zn
J) NaNO3 (small 3 ~ slightly below letters)
F) element - iron
G) compound and the elements it contains are aluminium and chlorine
H) compound and the elements it contains are hydrogen and bromine
I) element - zinc
J) compound and the elements it contains are sodium, nitrogen and oxygen
The formula of 5 substances are listed below, state whether it’s an element or compound and name the elements it contains:
K) S8 (small 8 ~ slightly below letters)
L) C6H12O6 (small 6, small 12, small 6 ~ slightly below the letters)
M) He
N) Pb
O) Ag
K) element - sulfur L) compound and the elements it contains are carbon, hydrogen and oxygen M) element - helium N) element - lead O) element - silver
What type of substance is a compound
A pure substance
What occurs when a compounds is formed and there is an energy change
A chemical reaction
The composition of a compound is what
Always the same
The properties of a compound are……
from those of the elements making up the compound
Different
Chemical compounds are………to separate and can only be broken down by chemical means e.g. Molten sodium chloride can be decomposed to give sodium and chlorine…………
Difficult
By electrolysis
A mixture contains how many substances
Two or more
When a mixture is made what does or doesn’t take place
No chemical reaction takes place
The composition of a mixture can what
Vary
The properties of a mixture are the……as those of the individual elements making up the mixture
Same
Mixture are…..to separate using physical means.
E.g. Sodium chloride crystals be obtained from sodium chloride solution………………..
Easy
By evaporation
What is sulfur
A yellow solid with a pungent smell
What does iron conduct
Heat and electricity
What does iron sulfide contain
Two elements which are chemically combined
What can iron and sulfur be separated into and how
Into two elements, using a magnet
A boy found a lump of yellow mineral he thought it was either gold or sulfur, what can he deduce from the following results:
It does not conduct electricity - not gold
It did not melt when heated with a Bunsen burner - not sulfur
It did not catch fire when heated in air - not sulfur
Could the mineral have been either sulfur or gold
No it couldn’t have been either
What have copper, iron, sulfur and tin all have in common
They are all elements
How does sulfur differ from copper, iron and tin
It’s a non metal whereas the rest are, plus sulfur doesn’t conduct electricity and isn’t magnetic
What have carbon dioxide, iron oxide, sulfuric dioxide and water all have in common
They are all compounds
In what way does iron oxide differ from carbon dioxide, sulfur dioxide and water
Iron is the metal oxide
Chemicals can be identified by symbols, formulae or names. Five examples of chemicals found in school labs are given below:
C MgO Sodium chloride Mg CuSO4
Give the name of a chemical from the list which is an element
Magnesium and carbon
Chemicals can be identified by symbols, formulae or names. Five examples of chemicals found in school labs are given below:
C MgO Sodium chloride Mg CuSO4
Write down the formula for sodium chloride
NaCl
Chemicals can be identified by symbols, formulae or names. Five examples of chemicals found in school labs are given below:
C MgO Sodium chloride Mg CuSO4
What is the name of the last chemical labelled CuSO4
Copper sulphate
Four chemicals are labelled below, answer the questions corresponding to them:
CuSO4 P MgO MnO2
What is the name of the element which has he symbol P
Phosphorus
Four chemicals are labelled below, answer the questions corresponding to them:
CuSO4 P MgO MnO2
Which chemical contains magnesium oxide, a, b, c or d
C
Four chemicals are labelled below, answer the questions corresponding to them:
CuSO4 P MgO MnO2
Why can magnesium oxide be described as a compound
Because it is made up of two different elements, magnesium and oxygen. (Which have chemically bonded)
Give two elements which are made up of small molecules
Oxygen and nitrogen
Give the definition of the term soluble
A solid that dissolves easily in a liquid solvent e.g. Sugar, salt
Give the definition of the term insoluble
A solid that does not dissolve easily in a liquid solvent e.g. Sand
Give the definition of the term solute
A solid that dissolves.
This is a substance that changes its state during a dissolving process i.e. The substance that dissolves e.g. Sugar, salt
Give the definition of the term solvent
This is a substance that does not change its state during a dissolving process i.e. The substance in which the solute dissolves e.g. Water
Give the definition of the term solution
A mixture containing the solute and solvent
Solution = solvent + solute
Give the definition of the term residue
Solid particles trapped in filter paper e.g. Sand
Give the definition of the term filtrate
Liquid particles that pass through the filter paper
Give the definition of the term distillate
The liquid that condenses during distillation and is collected
Give the definition of the term miscible
A liquid that mixes easily in another liquid e.g. Ethanol and water
Give the definition of the term immiscible
A liquid that does not mix easily in another liquid e.g. Oil and water
What is filtration used to separate
An insoluble solid from a liquid e.g. Sand and water
What is Evaporation/Crystalisation used to separate
Used to separate a solute from a solvent e.g. Salt and water
What is a separating funnel used to separate
Used to separate two immiscible liquids e.g. Oil and water
When using chromatography why do we draw the base line in pencil
As the pencil doesn’t contain dyes and won’t dissolve
Name an instrumental method which could be used to separate the food dyes in an orange juice drink
High performance liquid chromatography (HPLC)
What is the boiling point of water
100°
What is the boiling point of ethanol
78°
Which of the following statements about a sugar lump dropped into warm tea is false?
A) the particles of sugar are more widely separated in the solution than in the sugar lump
B) the particles of sugar move about more freely in the solution than in the sugar lump
C) the sugar lump melts in the warm tea
D) the sugar lump is bombarded more vigorously by the water particles in warm tea than in cold tea
C
Using the technique of mass spectrometry chemists can do what
Accurately compare the masses of atoms and molecules
The spectrum of an example of mass spectrometry shows a result for a sample of chlorine, it shows two different peaks one with mass of 35 and the other 37 (the peak of Cl 35 is triple the night of Cl 37)
What does the height of the peaks tell you
The relative amount of each element present
The spectrum of an example of mass spectrometry shows a result for a sample of chlorine, it shows two different peaks one with mass of 35 and the other 37 (the peak of Cl 35 is triple the night of Cl 37)
What is the ratio of relative proportions of Cl-35 and Cl-37
3:1
Therefore for every 4 chlorine atoms, 3 of them will be chlorine 35 and one of them will be chlorine 37
The spectrum of an example of mass spectrometry shows a result for a sample of chlorine, it shows two different peaks one with mass of 35 and the other 37 (the peak of Cl 35 is triple the night of Cl 37)
Using the info from the spectrum for chlorine work out the average and hence the value for RAM of chlorine. Bare in mind there is a ratio of 3:1
Average mass = mass x abundance
——————-
Total abundance
= (3x35) + (1x37) (75x35) + (25x37)
—————– OR ——————-
4 100
= 35.5 =35.5
Exercise 1.7:
The spectrum shows the mass spectrum of methane, there is a peak shown as mass/charge ratio of 16:
Can you explain this peak shown
Methane is CH4
RMM of CH4 = 12 + (4x1)
= 16
The mass spectrum peak at 16 corresponds to its RMM (relative molecular mass)
Predict what value you would expect to find a peak at for ethanol C2 H5 OH
(2x12) + (5x1) + 16 + 1
= 46
By carefully interpreting data from mass spectrometry we can deduce what
- the relative atomic masses of elements
- the number of isotopes an element contains
- the relative molecular masses of compounds and molecules
High performance liquid chromatography (HPLC):
What is this used to determine
The number of components in a mixture
High performance liquid chromatography (HPLC):
How do we know how many components there are in a mixture
Due to the number of peaks
Where is gas liquid chromatography widely used in
The petrochemical industry, environmental monitoring and in chemical methods
What are the benefits of using mass spectroscopy
Fast analysis
Results can be linked to database to identify substance
What are the drawbacks of using mass spectroscopy
Expensive equipment
Presence of isotopes leads to more than one peak
What are the benefits of using HPLC
Fast
Accurate
Use only minute samples
What are the drawbacks of using HPLC
Sample must be liquid
Expensive
State on disadvantage of HPLC
Expensive
What label should be placed on the trace at y with a HPLC trace obtained using a mixture
Retention time
If there are 2 peaks on a chromatogram, how many components are present in the mixture
2
Investigating the properties of iron, sulfur and iron sulfide: List the appearances of these materials: Iron Sulfur Iron-sulfur mixture Iron sulfide
Iron - grey solid
Sulfur- yellow solid
Iron-sulfur mixture - grey and yellow solid mix
Iron sulfide - grey/black solid
Investigating the properties of iron, sulfur and iron sulfide:
List if these materials are magnetic or non magnetic:
Iron
Sulfur
Iron-sulfur mixture
Iron sulfide
Iron - attracted ~ magnetic
Sulfur- not attracted ~ non magnetic
Iron - sulfur mixture = iron attracted (magnetic) sulfur is not attracted (non magnetic)
Iron sulfide - not attracted ~ non magnetic
Investigating the properties of iron, sulfur and iron sulfide:
List the observations of these materials:
Iron
Sulfur
Iron-sulfur mixture
Iron sulfide
Iron - bubbles
Sulfur - no reaction
Iron-sulfur mixture ~ iron reacts, sulfur doesn’t
Iron sulfide - rotten egg smell
Investigating the properties of iron, sulfur and iron sulfide:
Write a word equation for the formation of iron sulfide
Iron + sulfur —> iron sulfide
Investigating the properties of iron, sulfur and iron sulfide:
Conclusion
Different elements have different properties. In a mixture the elements behave as if they were in their own. A compound is a new material that has its own properties
When performing chromatography why is it important that the samples to be separated are above the solvent level in the beaker
Otherwise they will dissolve in the water
When separating two immiscible liquids via a separating funnel e.g. Oil and water which is on top
Oil is on top and water is on the bottom
