Unit 1.6 - The Periodic Table Flashcards
What do elements in the same group have?
The same number of electrons in the outer shell
Which elements have the same number of electrons in the outer shell?
Elements in the same group
What do elements in the same group form?
Compounds with similar formulae and properties
How does the atomic radius change when going down the groups and why?
There’s an increase in the number of filled shell which leads to an increase in atomic radius
What causes an atomic radius to increase?
The number of filled shells
What’s the difference between the different atomic radius’ of different elements?
A difference of nm’s
Which element has the largest atomic radius?
Caesium
Which properties change whilst going down the groups in the periodic table?
-Atomic radius
-First ionisation energy
-Melting points
-Electrongativity
What happens to the first ionisation energy of elements a you move down the groups and why?
Decreases, as the outer electron has a larger amount of screening and distance from the nucleus, which outweighs the fact that it has an increased nuclear charge, meaning that there’s less energy required to remove electrons from the atom, so there’s a decrease in 1st ionisation energy
What happens to the melting points of different elements as you move down the groups?
It’s not possible to make a definitive statement about the variation of melting points down a group - each group must be studied individually
What’s the trend in terms of melting point down group 1?
Melting points decrease
What’s the trend in terms of melting points in group 2?
No definite trend
What’s the trend in terms of melting point in group 7?
Melting points increase down a group
What happens to a reaction occurring with elements from group 1 moving down the group?
React more vigorously
Which group elements react vigorously with chlorine?
Group 1
What do group 1 elements react vigorously with?
Chlorine
Why do elements react more vigorously as you move down group 1?
-Larger atoms
-Attraction between electron and nucleus is weaker as they’re further away, so it’s easily lost
What do the fact that the atoms are bigger and that the attraction between the electrons and nuclei are weaker mean for the elements moving down group 1?
They react more vigorously
Electronegativity definition
The ability of an atom to attract a pair of electrons to itself in a covalent bond
The ability of an atom to attract a pair of electrons to itself in a covalent bond
Electronegativity
What happens to the Electronegativity of elements as you move down a group and why?
Decreases due to increased screening
What happens to the Electronegativity of elements as you move across the periods and why?
Increases (UP TO GROUP 7) due to increased nuclear charge
What similar method of thinking for the explanations can we use when describing Electronegativity?
Ionisation energy
(E.g - references to shielding and nuclear charge)
In which direction on the periodic table does the Electronegativity value of elements decrease? Why?
Down a group
Increasing shielding
In which direction on the periodic table does the Electronegativity value of elements increase? Why?
Across a period
Increasing nuclear charge
Describe the Electronegativity values of metals
Low
Describe the electronegativity values of non-metals
High
Which type of elements have low electronegativity values?
Metals
Which type of elements have high electronegativity values?
Non-metals
What are the three most electronegative elements (in order from most to least)
F (most)
O
N
What is the most electronegative element?
F
What is electronegativity measured using?
A Pauling scale
What does a Pauling scale measure?
Electronegativity
What’s the significance of the difference in electronegativity between 2 atoms?
The larger the difference in electronegativity between 2 atoms, the more polar the covalent bond
What makes a covalent bond between two atoms more polar?
A larger difference in electronegativity between 2 atoms
What does an even higher difference in electronegativity between 2 atoms do?
Creates an ionic bond
When is an ionic bond present between 2 atoms?
When they have a particularly large (larger than a polar covalent bond) difference in electronegativity
What type of bond is in water?
Polar covalent bond
What does δ represent in water?
A partial charge (less than associated with ions)
What os used to represent a partial charge in water?
δ
What happens to the electrons in a compound (taking electronegativity into consideration)?
The bonding electrons are pulled towards the more electronegative element
Which element are electrons pulled towards in a compound?
The more electronegative element
What does the most electronegative element do within a compound?
Pulls the bonding electrons towards it
What makes the bond polar in water?
The bonding electrons are pulled towards the more electronegative element (oxygen, in the case of water)
Which is the most electronegative element in water?
Oxygen
List 4 properties that increase down a group
-Metallic character
-reducing power
-Ionic character of compounds
-Basic character of oxides
What is the trend for the following properties - Metallic character, reducing power, Ionic character of compounds and Basic character of oxides?
All increase down a group
List 3 properties that decrease down a group?
-Electronegativity
-Non-metallic character
-Oxidising power
What is the trend for the following properties - Electronegativity, Non-metallic character and Oxidising power?
All decrease down the group
What’s the name for elements that have properties intermediate between a metal and a non-metal?
Metaloids
Metaloids
Have properties intermediate between a metal and a non-metal
Give 2 examples of Metaloids and why you say this
Al and Si as they’re on the barrier between metals and non-metals on the periodic table
Which gases exist monoatomically?
Noble gases (group 0)
What do the noble gases exist as?
Monoatomic gases
Which group on the periodic table are the noble gases?
Group 0
What are on group 0 on the periodic table?
Noble gases
Which gas exists s a diatomic gas with a triple bond between two atoms?
Nitrogen
What does the fact that nitrogen has a triple bond between 2 atoms make it?
Unreactive
Why it nitrogen unreactive?
It has a triple bond between 2 atoms
What are some elements that can form acidic oxides when reacted with 02?
P, C, Cl and S
What do P, C, Cl and S do when reacted with 02?
Form acidic oxides
What type of metals are those in group 1?
Alkali metals
Where are the alkali metals on the periodic table?
Group 1
Which elements on the periodic table have giant molecular structures?
C and Si
What type of structures do C and Si have?
Giant molecular structures
What are the two most common elements
Oxygen then silicon
What’s the most common metal?
Aluminium
Describe P and S
-single molecular structures
-solid at room temperature
What does Na do (3 things)?
-floats on water
-melts
-reacts vigorously with water
Give an example of an element that floats on water
Na
Give an example of an element that reacts vigorously with water
Na
Oxidation
Loss of electrons
Reduction
Gain of electrons
Phrase for when an element loses electrons
Oxidation
Phrase for when an element gains electrons
Reduction
How can we tell when an element has been oxidised?
Increase in positive charge
How can we tell when an element has been reduced?
Decrease in positive charge
What’s the name for an ion that reduces?
Reducing agent
Reducing agent
Ion that reduces
What’s the name for an ion that oxidises?
Oxidising agent
Oxidising agent
Ion that oxidises
What happens to a reducing agent in a redox reaction?
Oxidised
What happens to an oxidising agent in a redox reaction?
Is reduced
Under which conditions are reducing agents oxidised and oxidising agents reduced?
In a redox reaction
Name 4 common oxidising agents
Oxygen
Chlorine
Bromine
Potassium manganite (VII)
What are oxygen, chlorine, bromine and potassium manganate (VII) all examples of?
Common oxidising agents
Name 4 common reducing agents
Hydrogen
Carbon
Carbon monoxide
Metals
What are hydrogen, carbon, carbon monoxide and metals all examples of?
Common reducing agents
Name 4 reactions that are NOT redox reactions
- Precipitation reactions
- Acid-base reactions
- Acid-carbonate reactions
- Thermal decomposition reactions
What are the following - precipitation reactions, acid-carbonate reactions, acid-base reactions and thermal decomposition reactions?
NOT redox reactions
What concept does using oxidation states use?
All compounds are ionic compounds, where every element has a specific oxidation state
Definition of oxidation state
The formal charge on the atom in a compound after the removal of the bonding electrons
What happens to the oxidation state of an element if it’s undergone oxidation?
Increase in oxidation state
What happens to the oxidation state of an element if it’s undergone reduction?
Decrease in oxidation state
What causes an increase in an element’s oxidation state?
Oxidation
What causes a decrease in an element’s oxidation state?
Reduction
What is the rule with increasing and decreasing oxidation states?
The sum of the increase in oxidation state must equal the sum of the decrease in oxidation state
What are carbon and carbon monoxide used in and why?
As reducing agents in the blast furnace
Which elements are used as reducing agents in the blast furnace?
Carbon and carbon monoxide
What’s the name for the group 1 metals?
Alkali metals
Where are the alkali metal on the periodic table?
Group 1
What are the group 2 elements?
Alkaline Earth metals
Alkaline Earth metals
Group 2 metals
What are the group 1 metals?
Li —> Cs (not Fr)
What are the group 2 metals?
Be —> Ba (not Ra)
Describe the electronic structure of group 1 metals
One electron in their outer shell - the s orbital is being filled = very reactive metals which form ionic compounds
Describe the electronic structure of group 2 metals
Two electrons in the outer shell - the s orbital is full
What do both group 1 and 2 metals form?
Ionic compounds
What form ionic compounds?
Group 1 and 2 metals (except Beryllium)
Which metals are the most reactive - group 1 or 2 ?
Group 1
What does Beryllium not do like the other group 1 and 2 metals?
Form ionic compounds
Which elements in the group 1 and 2 metals does not form ionic compounds?
Beryllium
Describe the difference in ionisation energy when moving across the period from group 1 to 2
Increase in nuclear charge with the same amount of screening and distance from the nucleus = more energy needed to remove one electron from an atom in group 2 = increase in ionisation energy
Which elements have the highest amount of ionisation energy - group 1 or 2 and why?
2 as there’s a higher nuclear charge whilst screening and distance from the nucleus remains constant = more energy required to remove an electron from an atom in group 2 = increase in ionisation energy
Describe the structures of the elements in group 1
Cubic
Which elements have a cubic structure?
Group 1
Describe and explain the melting points of group 1 elements upon moving down the group
The atoms get larger
The force of attraction between the atoms decrease
The energy required to melt the elements decreases
= low melting points (odd for a metal)
Do group 1 elements have low or high melting points?
Low (which is odd for a metal)
Why do the melting points of group 1 metals decrease down the group?
Atoms getting larger
Force of attraction between the atoms decreases
Energy required to melt the elements decreases
What happens to the reducing power of the elements on going down the group?
Increases
What does the fact that the reducing power of the elements increases upon going down the group mean?
The elements show an increased tendency to form ions (cations)
Word for elements showing an increased tendency to form ions
Reducing power
Describe the reactivity of elements upon doing down the group and explain this
Increases as it’s easier for a metal to lose an electron
What does the fact that it’s easier for metals to lose an electron upon going down the group make it?
More reactive
What happens to the reactivity of elements upon moving down the groups?
Increases
What happens to the reducing power of elements on moving down the groups?
Increases
In what type of reactions does the reducing power and reactivity of elements going down a group increase?
Redox reactions
Group 1 elements reactivity with water upon going down the group
Increases down the group
How do group 1 elements react with water?
Vigorously
What do group 1 elements do when reacted with water?
Float and move around on the surface before eventually dissolving
Which metals react most vigorously in water? (Group 1 or 2)
Group 1
Elements of which group float and move around on the surface of water before eventually dissolving when reacted with it?
Group 1
What is formed when a group 1 element reacts with water?
Hydrogen gas and an alkaline solution
When is hydrogen gas and an alkali solution created?
When a group 1 element reacts with water
Why is the final solution alkaline when a group 1 element reacts with water?
Due to the formation of the soluble OH
What happens to lithium when reacted with water?
Reacts least vigorously and doesn’t melt
Which group 1 metal reacts least vigorously with water and doesn’t melt?
Lithium
How does sodium react with water?
Melts to form a silvery ball on the water’s surface and hisses as it moves on the surface of the water
Which element melts to form a silvery ball on water’s surface and hisses as it moves on the surface of water when it’s reacted with it?
Sodium
What does potassium do when reacted with water?
Catches fire and burns with a lilac flame
Which element catches fire and burns with a lilac flame when reacted with water?
Potassium
Write the equation for sodium (a group 1 metal) reacting with water
2Na + 2H20 —> 2NaOH + H2
Describe the reactivity of group 2 elements
Less reactive than group 1 elements
What happens when magnesium reacts with cold water?
Reacts very slowly (takes many weeks to collect a sample of hydrogen gas)
A white suspension of magnesium hydroxide forms
Which group 2 element reacts very slowly with water and takes many weeks to generate a sample of hydrogen gas?
Magnesium
HOW slowly does magnesium react with water?
Takes many weeks to collect a sample of hydrogen gas
How do group 2 elements react with water?
Readily (apart from magnesium)
What’s the only group 2 element that doesn’t react readily with water?
Magnesium
What do group 2 elements do when reacted with water?
Sink (denser than group 1 metals)
Do not melt (high melting points)
Dissolve to leave a solution that’s slightly milky due to the hydroxide forming and bubbles due to the hydrogen gas released
Which group of metals - 1 or 2 - sink in water and why?
Group 2 as they’re denser
Why do group 2 elements not melt in water?
Have high melting points
What can we see when a a group 2 metal is reacted with water and why?
Metal dissolves to leave a solution that’s slightly milky due to the hydroxide forming
Bubbles as hydrogen gas is released
What type of reaction occurs with magnesium and steam?
Violent reaction
Which element has a violent reaction with steam?
Magnesium
What happens when magnesium reacts with steam?
Magnesium OXIDE and hydrogen form
Magnesium burns with a brilliant flame
When does magnesium form magnesium OXIDE and hydrogen and burn with a brilliant flame?
When reacted with steam
Brilliant flame
Very bright
Very bright flame
Brilliant flame
Equation for the reaction of magnesium with steam
Mg + H20(g) —> MgO + H2
Equation for magnesium with cold water
Mg + 2H20 —> Mg(OH)2 + H2
Describe the reaction between group 1 elements and oxygen
Combine spontaneously
What do group 1 elements do when reacted with oxygen? What must we do as a result of this?
Combine spontaneously
Stored under oil
Why are group 1 elements stored under oil?
Combine spontaneously with oxygen
What happens when a group 1 element is reacted with oxygen?
Burn vigorously to form an oxide which is a white solid
What is the oxide formed when group 1 elements react with oxygen?
A white solid
Equation for reaction between sodium and oxygen
4Na + 02 —> 2Na20
What happens to group 2 elements when reacted with oxygen?
Burn fiercely to form an oxide (white solid)
What do both group 1 and 2 elements do when reacted with oxygen?
Burn fiercely to form an oxide (a white solid)
How does magnesium react with oxygen?
Burns with a brilliant flame
Which group 2 element burns with a brilliant flame in oxygen?
Magnesium
Equation for the reaction between magnesium and oxygen
2Mg + 02 —> 2MgO
How do group 1 and 2 elements react with acid?
The reaction is too vigorous to carry out with metals apart or magnesium
Which metal is the only one that doesn’t react too vigorously with acids in order to be done?
Magnesium
Describe the reaction between magnesium and acids
-reacts quickly with dilute acids
-the mixture effervesces
-magnesium dissolves to leave a colourless solution
-exothermic
-hydrogen forms
What does a metal form when it reacts with an acid?
A salt and hydrogen
Equation for magnesium reacting with sulphuric acid
Mg + H2S04 —> MgS04 + H2
Equation for the reaction between magnesium and hydrochloric acid
Mg + 2HCl —> MgCl2 + H2
Equation for the reaction between magnesium and nitric acid
Mg + 2HNO3 —> Mg(N03)2 + H2
What is the test for hydrogen?
Burns wit a squeaky pop
Which gas burns with a squeaky pop?
Hydrogen
What reflects on how elements are stored?
Their reactivity
Which group 2 elements are stored without any specific precautions? Why?
Magnesium and calcium as they’re not as reactive as the other group 2 elements
How are magnesium and calcium stored?
Without any specific precautions
Which group 2 elements are stored under special precautions and what are these?
Strontium and barium - under oil
Which group 2 elements are stored under oil? Why?
Strontium and barium as they’re more reactive than magnesium and calcium
Which group’s elements are all stored under oil?
Group 1 elements
How are group 1 elements stored?
Under oil
What do group 1 and 2 elements all act as in their reactions and what happens to them?
Reducing agents and are oxidised (lose electrons)
Which elements always act as reducing agents in their reactions and what does this mean?
Group 1 and 2 elements - they’re oxidised (i.e - they lose electrons)
Equation to show calcium being oxidised (as it’s a reducing agent)
Ca —> Ca2+ + 2e-
Why are group 1 and 2 elements described as mainly ionic?
They lose electrons readily to form cations
Do elements in group 1 and 2 lose electrons readily? What does this allow them to do?
Yes, to form cations
So, they’re mainly ionic
What are the oxides and hydroxides and why?
Strong bases as they are ionic compounds
What does the fact that group 1 and 2 elements are ionic compounds make them?
Strong bases
Sodium oxide formula
Na20
Sodium hydroxide formula
NaOH
Calcium oxide formula
CaO
Calcium hydroxide formula
Ca(OH)2
What’s the oxidation state of sodium in sodium hydroxide?
+1
What’s the oxidation state of sodium in sodium oxide?
+1
What’s the oxidation state of calcium in calcium hydroxide?
+2
Whats the oxidation state of calcium in calcium oxide?
+2
Na20
Sodium oxide
What are group 1 oxides?
Basic oxides
What do group 1 oxides do in water?
Dissolve readily to give strongly alkaline solutions containing hydroxide ions
What oxides dissolve the most readily in water - group 1 or 2?
Group 1
Equation for the reaction between sodium oxide and water
Na2O + H20 —> 2NaOH
Describe group 1 hydroxides in water
Very soluble (except lithium hydroxide which is sparingly soluble)
Which group 1 hydroxide is sparingly soluble in water?
Lithium hydroxide
Which group 1 hydroxide is different and how?
Lithium hydroxide, as it’s only sparingly soluble in water
What’s an alkali?
A soluble base
Soluble base
Alkali
What are group 2 oxides?
Basic oxides
Describe group 2 oxides in water
Do not dissolve as readily in water as group 1 oxides
Gives strongly alkaline solutions containing hydroxide ions
What do both group 1 and 2 hydroxides do in water?
Give strongly alkaline solutions containing hydroxide ions
Equation for the reaction between calcium oxide and water
CaO + H20 —> Ca(OH)2
Describe group 2 hydroxide’s solubility in water
Sparingly soluble
Solubility increases down the group
Which is the most soluble in water - group 1 or 2 hydroxides?
Group 1
What’s the trend in terms of solubility down the group for group 2 hydroxides?
Solubility increases down the group
What’s magnesium hydroxides solubility in water?
Insoluble (0.009gdm^-3)
What’s calcium hydroxides solubility in water?
Sparingly soluble (1.56gdm^-3)
What’s strontium hydroxides solubility in water?
Sparingly soluble (9gdm^-3)
What’s barium hydroxides solubility in water?
Soluble (39gdm^-3)
What observation could we make if something is insoluble in water?
Precipitate would form
What would an element have to be in a particular solution for us to see a precipitate forming?
Insoluble
What would we be able to see if something was soluble?
Nothing
What would a particular element have to be in a particular solution for us to see nothing?
Soluble
Describe the group 2 carbonates in water
All are insoluble
What happen when the group 2 carbonates react with dilute acid?
Form a salt and water and release CO2 gas, which turns limewater milky
When reacting with what does a carbonate form a salt and water and releases CO2 gas?
Dilute acid
What turns limewater milky?
CO2 gas released when a carbonate reacts with a dilute acid
What does the CO2 released from a carbonate when it reacts with acid do?
Turns limewater milky
Word for a cloudy solution
Turbid
Turbid meaning
Cloudy solution
Equation for calcium carbonate reacting with hydrochloric acid
CaCO3 + 2HCl —> CaCl2 + CO2 + H2O
Describe the solubility of group 2 sulfates in water
Solubility decreases down the group
Describe magnesium sulfate in water
Soluble
Describe calcium and strontium sulfate in water
Sparingly soluble in water
Describe barium sulfate in water
Insoluble
What does barium sulfate appear as in water?
Thick white precipitate
What forms a thick white precipitate when reacted with water?
Barium sulfate
What are the majority of group 2 cations reactions?
Precipitate reactions (white ppt)
The majority of which reactions form white precipitates?
Group 2 cations
Magnesium cation and OH-
White precipitate
Calcium cation and OH-
Cloudy/sparingly soluble
Barium cation and OH-
Soluble
Magnesium cation and CO32-
White precipitate
Calcium cation and CO32-
White precipitate
Barium cation and CO32-
White precipitate
Magnesium cation and SO42-
Soluble
Calcium cation and SO42-
Cloudy/sparingly soluble
Barium cation with SO42-
White precipitate
Ionic equation for magnesium and hydroxide ions
Mg2+ (aq) + OH- (aq) —> Mg(OH)2 (s)
Ionic equation for calcium and carbonate ions
Ca2+ (aq) + CO32- (aq) —> CaCO3 (s)
Ionic equation for barium and sulfate ions
Ba2+ (aq) + SO42- (aq) —> BaSO4 (s)
What are flame tests used for?
Identifying group 1 and 2 cations
What do we use to identify group 1 and 2 cations?
Flame tests
What’s the issue with platinum wires? What do we therefore use instead for flame tests?
Expensive and fragile
Wet wooden splints
What’s the alternative to using wet wooden splints in flame tests? What’s the issue with these?
Platinum wires
Expensive and fragile
Steps for completing flame tests
- Dip a platinum wire into concentrated HCl
- Dip the tip of the wire in the solid to be tested
- Tip of the wire is placed in the blue Bunsen flame
- Note the colour of the flame
What is dipped into the acid for a flame test and what type of acid is this?
Platinum wire/wet wooden splint
HCl
How much of the wire/splint do we dip into the solid and flame when completing a flame test?
Just the tip
What colour flame should be on the Bunsen when completing a flame test?
Blue
What type of analysis is the flame test? For what?
Qualitative to identify metal cations (all different metal ions give off different flame colours)
Which colour flames do we need to take care in order to not get confused between?
Red flames
Which colour flames can look similar during flame tests?
Red flames
Lithium cation flame colour
Red
Which metal cation gives a red flame?
Lithium
Sodium flame colour
Intense yellow
Which metal cation gives off an intense yellow flame?
Sodium
Potassium flame colour
Lilac
Which metal cation gives off a lilac flame?
Potassium
Magnesium flame colour
No colour
Which metal cation gives off no colour?
Magnesium
How can we identify different metal cations?
Using the flame tests
Calcium flame colour
Brick red
Which metal cation gives off a brick red flame?
Calcium
Strontium flame colour
Crimson
Which metal cation cation gives off a crimson flame?
Strontium
Barium flame colour
Green-yellow (apple green)
Which metal cation gives off a green-yellow (apple green) flame colour?
Barium
Crimson colour
Red/purple ish (flame colour for strontium ion)
Which group 2 elements are important in living systems?
Magnesium and calcium
What are magnesium and calcium important in?
Living systems
What’s in the exoskeleton of many animals?
Calcium carbonate
What’s calcium carbonate in?
Exoskeleton of many small animals
Example of small animals with an exoskeleton
Shellfish
What ARE limestone and chalk?
CaCO3
How is CaCO3 useful to us?
Limestone and chalk deposits (CaCO3) are the fossil remnants of prehistoric animals
What are the fossil remnants of prehistoric animals?
Limestone and chalk (CaCO3)
Which element forms the major part of the skeletons of vertebrate animals?
Calcium phosphate
What does calcium phosphate do?
Forms a major part of the skeletons of vertebrate animals
Why is chlorophyll important and what does it contain?
Important in photosynthesis - contains magnesium ions
What important component of nature contains magnesium ions?
Chlorophyll
What must ATP be bound to in order to be biologically active?
A magnesium ion
Why must ATP be bound to a magnesium ion?
In order to be biologically active
What is ATP important for?
The main source of energy in cells - plays an important role in metabolic reactions in the body
What is the main source of energy in cells that plays an important role in metabolic reactions in the body?
ATP
What’s the name for the elements in group 7?
Halogens
In which group are the halogens?
Group 7
Are halogens metals or non-metals?
Non-metals
Describe the changes experienced by the halogens with increasing atomic mass
Gradual changes
Which halogen is corrosive?
Bromine
Describe bromine
Corrosive
Which two halogens are good disinfectants?
Chlorine and iodine
What are chlorine and iodine good as?
Disinfectants
What is iodine a good disinfectant for?
Skin in surgery
What is used as a disinfectant for skin in surgery?
Iodine
What is used as a disinfectant in public drinking water and pools?
Chlorine
What’s chlorine used as?
A disinfectant in public drinking water and pools
Chlorine appearance at room temperature
Yellow-green gas
Room temperature
25 degrees Celsius
Bromine appearance at room temperature?
Dark orange liquid
Iodine appearance at room temperature
Dark purple/grey solid
Which halogen is a yellow-green gas at room temperature?
Chlorine
Which halogen is a dark orange liquid at room temperature?
Bromine
Which halogen is a dark purple/grey solid at room temperature?
Iodine
Electronegativity of chlorine
3.2
Which halogen has 3.2 as its Electronegativity?
Chlorine
What’s bromine’s electronegativity?
3.0
Which halogen has 3.0 as its Electronegativity?
Bromine
What’s iodine’s electronegativity?
2.7
Which halogen has 2.7 as its Electronegativity?
Iodine
Melting point of chlorine (Celsius)
-101
Melting point of bromine (Celsius)
-7
Melting point of bromine
114
Which halogen has a melting point of -101?
Chlorine
Which halogen has a melting point of -7?
Bromine
Which halogen has a melting point of 114?
Iodine
Boiling point of chlorine
-34
Which halogen has a boiling point of -34?
Chlorine
Boiling point of bromine
58
Which halogen has a boiling point of 58?
Bromine
Boiling point of iodine
183
Which halogen has a boiling point of 183?
Iodine
Are the halogens reactive?
Yes
What type of molecules do the halogens exist as?
Diatomic
What do the halogens form with non-metals?
Covalent compounds
With what do the halogens form covalent compounds?
Non-metals
What do the halogens form with metals?
Anions - produce ionic compounds known as salts
When reacted with what do the halogens form anions and ionic compounds known as salts?
Metals
Describe the structure of the halogens
Simple molecular structure
What are the atoms held together with in the halogens?
Non-polar covalent bonds within molecules
What are within the molecules of halogens and what does this do?
Non-polar covalent bonds that hold atoms together
Is there a dipole within a halogen molecule?
No
What happens to the melting and boiling points of the halogens down the group?
Both increase
Why do the halogens have higher melting and boiling points down the group?
Increase in size and molar mass - stronger van der Waal forces
What type of forces does an increase in size and mass in the halogens create stronger ones of?
Van der Waal forces
What creates stronger van der Waal forces in the halogens down the group?
Increase in size and molar mass
What happens to the electronegativity of the halogens down the group?
Decreases
Why does the electronegativity of the halogens decrease down the group?
Increased screening (it always does decrease down the group)
How is the reactivity of the halogens affected down the group?
Decreases
What’s does a decrease in the electron activity of elements down the group lead to?
Decreased oxidising power
What happens to the oxidising power of the elements down the groups and why?
Decreases due to decreased electronegativity
What’s the most powerful oxidising agent?
F
What happens to he reducing owner of the halide ions down the group?
Increases
Halide ions
Negatively charged halogen ions
Negatively charged halogen ions
Halide ions
Anions
Negatively charged ions
Negatively charged ions
Anions
How are anions formed by the halogens?
By gaining electrons to obtain a full outer shell
What are formed when a halogen gains electrons to obtain a full outer shell?
Anions
Write out the formula for Florine gaining electrons to form an anion
F2 + 2e- —> 2F-
What happens to the tendency to form ions down the group?
Decreases
What do halogens do to metals?
Oxidise them
Write the reaction between sodium and chlorine
Na + Cl2 —> 2NaCl
Write the reaction between iron and chlorine o form iron (iii) chloride
2Fe + 3Cl2 —> 2FeCl3
What type of reaction is the reaction between a halogen and a halide ion?
Redox reaction
What do the halogens act as during redox reactions?
Oxidising agents
Which halide ions do he halogens oxidise/displace?
Those LOWER in the group
What happens to the halide ions lower than the halogens in the group during a redox reaction?
Oxidised/displaced
What happens to oxidising power down the groups?
Decreases
Which anions does chlorine oxidise?
Bromine and iodine anions
Which anions does bromine oxidise?
Iodide anions but not chloride anions
Which anions does iodine displace/oxidise?
Neither chloride nor bromide anions
Write the reaction of chlorine oxidising a bromine halide
Cl2 + 2Br- —> 2Cl- + Br2
Observations of the chlorine halogen reacting with the chloride halide solution
No reaction
Observations of the chlorine halogen reaction with the bromide halide
Yellow-orange Br2 formed
Observations of the chlorine halogen reacting with the iodide halide
Brown I2 solution
The reaction between which halogen and which halide forms yellow-brown Br2?
Chlorine halogen and bromide halide
The reaction between which halogen and halide forms a brown I2 solution?
Chlorine halogen and bromide halide
AND
Bromine halogen and iodide halide
Observations of the bromine halogen reacting with the chloride halide
No reaction
Observations of the bovine halogen reacting with the bromide halide
No reaction
Observations of the bromine halogen reacting with the iodide halide
Brown I2 solution
Observations of the iodine halogen reacting with the chloride halide
No reaction
Observations of the iodine halogen reaction with the bromide halide
No reaction
Observations of the opine halogen reacting with the iodide halide
No reaction
Which halogen reacting with 3 different halides always has no reaction? Why?
Iodine - it doesn’t displace any of them as the oxidising power decreases down the group
Is iodine soluble in water?
No
Describe iodine in water
Insoluble
What does iodine dissolve in?
Aqueous potassium iodide
What does iodine form when reacted with potassium iodide?
A red-brown solution containing I3- ions
When is a red-brown solution containing I3- ions created?
When iodine dissolves in aqueous potassium iodide
How do we test for halide ions
React silver nitrate with them
What does a reaction with silver nitrate test for?
Halide ions
What’s the first step for testing for halide ions?
Adding dilute nitric acid (to remove ions such as OH- that might interfere with the test) to the solution containing the halide
Why do we add nitric acid when testing for halide ions?
To remove ions such as OH- that might interfere with the test
Which acid is added when testing for halide ions?
Nitric acid
What happens when adding silver nitrate to the halide ions solution?
Precipitate of silver halide forms
What has to be done in order for a silver halide precipitate to be formed from silver nitrate solution?
- Add dilute nitric acid to remove interfering ions
- Add silver nitrate
What’s the final step of the reaction between silver nitrate and halide ions?
Add excess dilute ammonia solution
What is added to the silver halide solution in its test?
Dilute ammonia solution
Observation of the chlorine halide with nitric acid
No reaction
Observation of the bromide halide with nitric acid
No reaction
Observation of the iodide halide with nitric acid
No reaction
Observation of the chlorine halide with silver nitrate
White precipitate
Observations of the bromide halide with silver nitrate
Cream precipitate
Observations of the iodide halide with silver nitrate
Yellow precipitate
Which halide gives a white precipitate in silver nitrate?
Chlorine
Which halide gives a cream precipitate in silver nitrate solution?
Bromide
Which halide gives a yellow precipitate in silver nitrate?
Iodide
What’s the observation for all of the halides with nitric acid and why?
No reaction, as its only there to remove ions that might interfere with the test, such as OH-
Ions that would interfere with the halide ions and silver nitrate test
OH-
Observation of chlorine halide and dilute ammonia
Soluble
Observation of bromide halide and dilute ammonia
Mostly insoluble
Observation of iodide halide and dilute ammonia
Insoluble
Which halide is soluble in dilute ammonia?
Chlorine
Which halide is mostly insoluble dilute ammonia?
Bromide
Which halide is insoluble in dilute ammonia?
Iodide
Equation for the reaction between silver nitrate and chlorine halide
Ag+ (aq) + Cl- —> AgCl (s)
Describe chlorine in water
Slightly soluble - reacts slightly in a disproportionation reaction
What reacts with water in a disproportionation reaction?
Chlorine
Equation for the reaction between chlorine and water
Cl2 (g) + H20 (l) —> HCl (aq) + HClO (aq)
Why is the reaction between chlorine and water a disproportionation reaction?
Chlorine is simultaneously oxidised and reduced
What is the chloric (I) acid/bleach produced in the chlorine and water reaction’s formula?
HClO
HClO
Chloric (I) acid/bleach produced in the reaction between chlorine and water
What type of agent is HClO/chloric (I) acid?
Mild oxidising agent
What is HClO often used for and why?
Sterilising swimming pools and disinfecting public drinking water as it’s effective at killing bacteria without being harmful to humans
What is widely used to sterilise swimming pools and disinfect public drinking water?
Chloric (I) acid (HClO)
HClO
Chloric (I) acid
When is chlorine toxic to humans?
In anything other than very small doses
What has to be taken in very small doses and why?
Chlorine as it’s toxic at higher doses
Why does care Ned to be taken not to over-chlorinate the water supply?
Toxic to humans in anything other than very small doses
What has to be controlled in public drinking water? Why?
Chlorine levels as it’s toxic to humans at high dosages
Floride
Florine anion
Fluorine anion
Fluoride
What is added to water and toothpaste?
Floride
What is Floride added to?
Water and toothpaste
What is fluoride added to?
Water and toothpaste
Why is floride added to water and toothpaste?
Reduces tooth decay by cavity formation and strengthening bones
How is tooth decay reduced with fluoride?
Cavity formation and strengthening bones
What does a tooth contain and what does fluoride do to this?
Calcium fluoride - fluoride remineralises the tooth
Why does fluoride remineralise a tooth?
Tooth contains calcium fluoride
At what levels are the beneficial effects of fluoride experiences?
Under 1 ppm
How much fluoride do we need to add to drinking water?
Under 1ppm
In which forms is Floride added to public drinking water?
Fluorosilicic acid, sodium fluorosilicate and sodium fluoride
What are fluorosilicic acid, sodium fluorosilicate and sodium fluoride examples of?
How fluoride is added to public drinking water
What’s the short practical for investigate the properties of a group II oxide?
-Heat a calcium carbonate marble chip for around 15 minutes
-It will decompose into CaO
CaCO3 —> CaO + CO2
-Add water 1 drop at a time (forms a cloudy solution due to OH- ions)
What is limewater’s formula and how does it form?
CaO + H20 —> Ca(OH)2
If a reaction has gone cloudy, is the reactant soluble?
Sparingly soluble
How would a sparingly soluble reactant appear in a reaction?
Cloudy
Why is Mg(OH)2 a weak alkali?
As it’s insoluble, and an alkali is a soluble base
Nature of oxides and hydroxides down the group and why
Become more basic/alkaline down the group
(Less stable lone pairs of electrons)
What is limewater?
Calcium hydroxide
What is calcium hydroxide also known as?
Limewater
How do we obtain CO2 for a reaction?
React a carbonate with an acid (the products of this reaction are salt, water and carbon dioxide) and esxtract the CO2 using a pipette
What are the observations to be made when bubbling CO2 when limewater?
Lime water turns cloudy or milky
Why does limewater turn milky when reacted with CO2?
CaCO3 forms a white precipitate
Upon reacting with water does lime water turn cloudy/milky?
Upon reaction with CO2
Why do oxides and hydroxides become more basic/alkaline down the group?
Less stable lone pairs of electrons
What do less stable lone pairs of electrons lead to?
More basic/alkaline elements
Group 1 carbonates and water
All soluble except lithium
Trend of the solubility of carbonates down the group
Less soluble down the group
What’s the trend for the solubility of the hydroxides down the group?
Increases
Group 1 sulfates solubility in water
Soluble
Which elements have the highest melting temperatures and why?
C and Si as they have giant covalent structures
What does having giant covalent structures cause for an element?
Causes it to have a higher melting temperature
What only increases up to group 7?
Electronegativity
Where does electronegativity increase up to across the period?
Group 7
What’s a basic oxide?
An oxide that will react with acids (to form a salt)
An oxide that will react with acids
Basic oxide
What happens to melting points across a period and why?
Increases due to more outer electrons, so a stronger metallic bond
Which element in group 2 has a weird melting point?
Magnesium
What’s different with magnesium’s melting point compared to the other group 2 elements?
Weirdly low in the general decrease
Why is using a platinum wire technically better than using a wooden splint?
Inert (chemically inactive), whilst the wooden splints may just burn the colour of the wood
Inert
Chemically inactive
Chemically inactive
Inert
Problem with using wooden splints in flame tests
Splints could burn the colour of the wood, whereas platinum wires are inert
Volatile
Easily evaporated at room temperatures
Easily evaporated at room temperatures
Volatile
Do elements become more or less volatile down the group and why?
Less volatile
(Increase in size = stronger Van der Waal forces)
Give the shape of a H3NBH3 molecule and show your working
(See notes)
What’s good about forming a coordinate bond when an atom doesn’t have enough electron pairs to form an octet?
Don’t have to use all of those molecule’s electrons
How do you test for sulfates?
- dilute hydrochloric acid
- barium chloride
= white precipitate
Why must the wire be cleaned before carrying out a flame test?
To remove any unwanted ions that might obscure the colour of the flame
Describe all group 1 compounds in water
ALL SOLUBLE
(the rules about increasing and decreasing solubility applies to group 2 elements!)
What happens to the thermal stability of hydroxides and carbonates down the group?
Increases
Hydroxides when heated
Decompose to the oxide and steam
Carbonates when heated
Decompose to the oxide and CO2
How do you prepare an INsoluble salt?
Precipitation reaction
(2 solutions form both a soluble and an insoluble salt)
At which point does electronegativity stop increasing across the period?
Up to group 7
What’s happens to the stability of the carbonates down the group?
Increases
What are basic oxides usually formed by?
Reaction of oxygen with metals, especially alkali and alkaline earth metals
What would happen if you left calcium hydroxide out at night? Why?
It would form a white precipitate
CO2 would be absorbed and CaCO3 would form
How does the periodic table have the elements arranged?
By increasing number of protons
Why does argon have a greater atomic mass than potassium?
It has a greater number of neutrons (atomic mass is protons + neutrons)
Why do group 1 elements react more vigorously in water than group 2 elements?
They only lose one electron, therefore they easily form cations
Summarise the stages of graviametric analysis
Analyte
Precipitate form
Filtration
Drying
How do we treat a precipitate?
Wash and dry
Why do we wash a precipitate?
Remove unreacted ions
Why would we dry a precipitate?
To remove water
To which stage would we dry a precipitate?
To constant mass
Why must we always add an excess of reagent that reacts with analyte?
To ensure that it fully reacts
What’s the molar ratio of compound formed to ions in gravimetric analysis questions?
1:1
Percentage by mass equation
Mass present
——————. x100
Mass of impure sample
Gravimetric analysis
Analysis using mass
Analysis using mass
Gravimetric analysis
Describe the trend in melting points across the period, using group 2 as an example
Li —> C = increases
Metallic to covalent bonds
C —> F = decreases
Weak van der Waal forces
Where is the highest boiling point always in a period and why?
Group 4
Giant covalent ( covalent bonds are stronger than metallic bonds )
What happens to oxidising power across a period?
Increases
What do all group 1 metals do in water?
Float, move, fizz
What do all group 2 metals do in water?
Sink, fizz, cloudy
Why does the flame on the Bunsen burner have to be blue during a flame test?
So as not to block the colour change
Why couldn’t we add nitric acid when testing for halide ions?
Contributes Cl ions = false test
Observations of reacting chlorine and sodium
Yellow flame, white solid
Observations of reacting iron and chlorine
Orange flame, brown solid
What form basic oxides?
Mainly group 1 and 2 elements
