Section 2 chemistry of the elements Flashcards
in the periodic table what are the rows and columns called?
rows - periods
columns - groups
group 0 are inert what does this mean?
they dont react much
group 1 elements become more reactive as you go…………………..
down the group
What does a reaction with water and alkali metal produce?
The Metal hydroxide and hydrogen.
What alkali metal (in group 1) reacts the most?
Potassium - lilac flame sometimes explosion
Why is potassium more reactive than sodium or lithium?
It’s outer shell electrons are lost easier because they are further away from the nucleus so feel less nuclear attraction, so if can lose electrons easier, it is more reactive!
What is the name of the group 7 elements?
The halogens
As the atomic number of halogens increase the elements have a ………….
Darker colour
Higher
Melting point
The higher up group 7 the more ………….
Reactive it is
What can halogens combine with to form hydrogen halides?
Hydrogen
When hydrogen chloride dissociates what is formed?
Hydrochloric acid
What happens in a displacement reaction?
More reactive halogens displace less reactive ones
What does a halogen displacement reaction involve?
Transfer of electrons
How do you test for hydrogen?
Put lit split in test with a reaction
If hydrogen present, will make a squeaky pop
What salts will hydrochloric acid produce?
Chloride
What salts do sulfuric acid produce?
Sulfate salts
What is produced when metal and water reacts?
Metal hydroxide and hydrogen
What is the order of reactivity?
Potassium, Sodium, Lithium, Calcium, Magnesium, Aluminium, Zinc, Iron, Copper, Silver, Gold.
Remember this by using: Please Say Little Charlie’s Monkeys And Zebras In Cages Securely Guarded.
What corrodes to make rust?
Iron and steel
What are the two types of protecting rust?
Barrier - plastics, oil
Sacrificial - using a more reactive metal
What percentage of each gas is in the atmosphere?
78% - nitrogen
21% - oxygen
Nearly 1% - argon
0.04% - CO2
How can you investigate the proportion of oxygen in the atmosphere?
Using copper
Using iron or phosphorus
How can you make oxygen in a lab?
Using hydrogen peroxide - decomposition
Manganese oxide catalyst
Collection - over water or a gas a syringe
2H2O ….. 2H2O + O2
What happens when magnesium, carbon and sulfur react with oxygen?
Magnesium - bright white flame, white powder, magnesium oxide, alkaline in water
Carbon - orange flame, produces carbon dioxide, acidic in water
Sulfur - pale blue flame, produces sulfur dioxide, acidic in water
What is upward and downward delivery used for?
Upward - collect lighter than air gases
Downward - collect heavier than air gases
What does the thermal decomposition of metal carbonates produce?
Carbon dioxide
What is carbon dioxide used in?why?
Fizzy drinks - slightly soluble in water, produces carbonic acid, makes drinks fizz
Fire extinguisher - more dense than air, sinks into flame and stops oxygen
Explain how carbon dioxide can be produced?
- Metal carbonate + acid ➡️ salt + water + carbon dioxide
- Thermal decomposition:
Metal carbonate ➡️ heat ➡️ carbon dioxide + metal oxide
What do greenhouse gases do?
Act as an insulating layer
Absorb heat and re radiate
How do you do a flame test?
Clean a platinum wire loop by dipping in HCL hold in the flame
Then dip in the sample and put back in the flame
What colour does the flame burn for Lithium Sodium Potassium Calcium
Lithium - crimson red
Sodium - orange
Potassium - lilac
Calcium - brick red
How can you identify a metal hydroxide?
Add a few drops of sodium hydroxide
If colour you can identify
What colour precipitate does copper and iron produce?
Copper - blue precipitate
Iron 2- green precipitate
Iron 3 - orange / brown precipitate
How can you test for ammonia gas?
Ammonia turns damp red litmus paper blue
How can you test for carbonates?
Add dilute hydrochloric acid to your sample
Carbon dioxide will be produced if carbonates are present.
How can you test for sulphates?
Add dilute hydrochloric acid and barium chloride solution to metal sulphate.
White precipitate of barium sulphate produced if sulfate ions present.
How can you test for halides?
Add nitric acid followed by silver nitrate
What happens to chloride, bromide and iodide when testing for halogens?
Chloride ion - white precipitate of silver chloride
Bromide ion - cream precipitate of solver bromide
Iodide ion - yellow precipitate of silver iodide
Why is acid used before the test for sulfates and halides?
To get rid of carbonates and sulfite ions
How do you test for chlorine?
Turns blue litmus paper red then bleaches it white
How do you test for oxygen?
Glowing splint will relight if oxygen is present.
How do you test for carbon dioxide?
Bubble your gas into limewater
Will turn cloudy if carbon dioxide is present.
How can you test for hydrogen?
Squeaky pop
Wet copper sulfate is ……….
Dry copper sulfate is …….
Blue
White
How do you test for water?
Add anhydrous copper sulfate and see if white powder turns blue. (will turn blue if water present)
How do you test for pure water?
Pure water will always:
Boil at 100 degrees C
Freeze at 0 degrees C
Dioxides are
Oxides are
Dioxides acidic
Oxides alkaline
What does redox mean?
Redox reactions are when reduction and oxidation reactions happen at the same time.
What is an oxidising agent?
An oxidising agent accepts electrons and gets reduced.
What is a reducing agent?
A reducing agent donates electrons and gets oxidised.
Describe the conditions under which iron rusts.
When the iron is in contact with both oxygen (from the air) and water.
How can the rusting of iron be prevented?
Paining it Coating with plastic Coating with grease Coating with oil Galvanising
Explain the sacrificial protection of iron.
It involves placing a more reactive metal with the iron. The water and oxygen then react with this sacrificial metal instead of with the iron to prevent rusting.
Explain the uses of iron in terms of properties.
It’s malleable, so is used to make gates and railings.
Can be mixed with elements to make alloys e.g. stainless steel for cutlery.
Explain the uses of aluminium in terms of properties.
Reacts quickly with oxygen in air to form aluminium oxide.
Doesn’t corrode so useful for products in contact with water e.g. Drink cans.
Less dense than iron, making it lighter so useful for bicycle frames and planes.
Name the metals in order of reactivity series from most reactive to least reactive.
Hint: Please Say Little Charlie’s Monkeys And Zebras In Lead Horrible Cages Securely Guarded Please
Potassium Sodium Lithium Calcium Magnesium Aluminium Zinc Iron Lead Hydrogen Copper Silver Gold Platinum
Describe how reactions with water and dilute acids can be used to deduce the order of reactivity of metals.
Very reactive metals will react vigorously with water e.g. potassium, sodium, lithium, calcium.
Less reactive metals won’t react with cold water but will react with steam e.g. copper, silver, gold.
What happens when lithium reacts with water?
Produces: lithium hydroxide and hydrogen
Observations: fizzing, gas, movement, floating, dissolves, exothermic.
What happens when sodium reacts with water?
Produces: sodium hydroxide and hydrogen.
Observations: fizzing, turns into a ball, melts, movement, dissolves, exothermic.
What happens when potassium reacts with water?
Produces: potassium hydroxide and hydrogen.
Observations: pink flame, fizzing, movement, dissolves.
What happens when magnesium reacts with hydrochloric acid / sulphuric acid?
With hydrochloric acid it produces: magnesium chloride and hydrogen.
With sulfuric acid it produces: magnesium sulphate and hydrogen.
Observations: effervesses, exothermic, hydrogen gas.
What happens when zinc reacts with hydrochloric acid / sulphuric acid?
With hydrochloric acid it produces: zinc chloride and hydrogen.
With sulphuric acid it produces: zinc sulphate and hydrogen.
Observations: slow and little reaction, few bubbles.
What happens when iron reacts with hydrochloric acid / sulphuric acid?
With hydrochloric acid it produces: Iron chloride and hydrogen.
With sulphuric acid it produces: iron sulphate and hydrogen.
Observations: slow and little reaction, 1 or 2 bubbles.
What happens when a metal reacts with an acid?
The metal salt and hydrogen are produced.
How could you test metals to place them in order of reactivity?
Using reactions with water and dilute acids. The most vigorous reactions are the most reactive metals.
What are the colours and physical States of the following elements at room temperature?
a) fluorine
b) chlorine
c) bromine
d) iodine
a) fluorine is a pale yellow gas at room temperature, produces yellow vapour.
b) chlorine is a pale green gas at room temperature, produces green vapour.
c) bromine is a red / orange liquid at room temperature, produces red / brown vapour.
d) iodine is a black / grey solid at room temperature, produces purple vapour.
When do displacement reactions occur?
A more reactive metal displaces a less reactive metal from a compound.
So can be used to determine order of reactivity.
Might be happening when there is a temperature increase or colour change in the reaction.
As you go down group 7 the reactivity of metals……….
Decreases
Describe an experiment to show that a more reactive halogen will displace a less reactive halogen from a solution of one of its salts.
Add a a few drops of a halogen solution e.g. chlorine / bromine / iodine water to a salt solution e.g. Potassium chloride.
Look for a colour change, meaning a displacement reaction has occurred.
Are displacement reactions reduction, oxidation or redox reactions? Why?
Redox because in displacement reactions reduction and oxidation happen simultaneously, which are called redox reactions.
What are halides (F-, Cl-, Br-, I-, At- etc) also known as?
Anions.
How could you test for different halides or anions?
Placing 2cm3 of halide into test tube
Add dilute nitric acids to acidify solution
Add a few drops of silver nitrate solution
Repeat test with another halide solution.
How would you show that a substance contains a halide ion?
Add dilute nitric acid Add silver nitrate If chloride present: White precipitate If bromide present: cream precipitate If iodide present: yellow precipitate.
How can you test for the cations copper, iron II and iron III?
Add sodium hydroxide to your solution containing an unknown metal ion, a precipitate will form, if:
Blue = copper
Green = iron II
Orange / brown = iron III
How can you test for the cations copper, iron II and iron III?
Add sodium hydroxide to your solution containing an unknown metal ion, a precipitate will form, if:
Blue = copper
Green = iron II
Orange / brown = iron III
What is a oxidising agent?
Accepts electrons and gets reduced
What is a reducing agent?
Donates electrons and gets oxidised
