C4.1 Flashcards
Where are the Group 1 elements and what are they also called?
In a vertical column in the far left of the periodic table and they are also called the alkali metals
What are some properties of Group 1
They are shiny when freshly cut, goof conductors of electricity and solid as room temp. They are very soft.
What is the hardest Group 1 metal
Lithium and it’s softer as you go down the group
What are the trends as you go down in Group 1
The density increases (sodium is unexpected) and their melting point decreases
Why are Group 1 metals stored in oil
This is as they react rapidly with the oxygen in the air and with water
What happens when Group 1 reacts with water?
They react with water to produce hydroxide of the metal and hydrogen
E.g if sodium reacts with water = sodium hydroxide and hydrogen
What happens when an Group 1 reacts with dilute acids?
- salt and hydrogen gas is produced
- these reactions are more violent than with water so dangerous to do in lab
What is the trend in reactivity as you go down in Group 1
The reactivity increases
How does Lithium react?
It fizzes steadily and slowly disappears
Who’s does Sodium react
It melts to form a silvery ball, fizzes vigorously and quickly disappears
How does potassium react
It floats on the surface and immediately ignites the hydrogen gas produced and burns with a lilac flame and then it disappears quickly
How does rubidium and caesium react with water?
- very violently with water - tend to explode when they get wet
How do you explain the trend in reactivity in Group 1
All their atoms have one electron in the outer shell. They lose their electrons in the outer shell in reactions and form ions with a positive charge.
M —> M+ + e-
The easier it is for the atom to lose the electron the more reactive it is. Elements lower down the group have elements with more shells and therefore have weaker electrostatic forces between the positive nucleus and negative electron
Where are the Group 7 elements found
Vertical column in the right of the periodic table
What is Group 7 also called
The halogens
What are the properties of Group 7
They are non metals and diatomic molecules
Weak imf
Brittle in the solid state
Poor conductors of electricity
What is fluorine in room temperature
Fluorine is a pale yellow gas
What is chlorine in room temperature
It’s a green gas
What is bromine in room temperature
It’s an orange brown liquid that vaporises easily
What is iodine are room temperature
It’s a shiny grey-black crystalline solid that sublimes to form a purple vapour
What are the trends in Group 7
The density increases and you go down
The melting and boiling points increase
What does Group 7 react with
They react with metals to produce salts
They react vigorously with Group 1 metals esp if it’s heated first
What happens to the reactivity in Group 7 as you go down the group
The reactivity decreases (opposite to alkali metals)
How do you explain the trends in activity in Group 7
They have similar chemical properties because all their atoms have seven electrons in the outer shell. They gain an electron in reactions to complete the outer shell and form one with a single negative charge.
X2 + 2e- —> 2X-
It’s easier for the halogen to gain an electron, the more reactive it is. As you go down the group, there are more electron shells acting as shields which means there is a weak electrostatic attraction between the positive nucleus and negative electron, making it harder to gain an electron.
What can halogens react with
Halogens can react with halides in a solution
What is a Halide
Compound which contains a Group 7 element and another element which is usually a hydrogen or metal
Hydrogen chloride and sodium chloride are halides
What is a Halide ion
It’s a negative ion formed by Group 7 elements ( e.g. chloride ions from chlorine)
When will a halogen replace a halogen
It’s will replace a less reactive halogen from its Halide ions in a solution
What does chlorine displaces
Chlorine displaces bromine from bromides and iodine from iodises
What does Bromine displace
Bromine displaces iodine from idolise but it can’t replace chlorine from chlorides
What can iodine displace
Iodine can’t displace chlorine from chlorides or bromine from bromides
What pattern do all halogen reactions follow
(Halogen 1)2 + 2(halogen 2) - > (halogen 2)2 + 2 halogen 1
E.g. cl2 + 2KBr —> Br2 + 2KCl
How can you use halogen displacement reactions to confirm the order of reactivity for chlorine, bromine and iodine?
- Wear eye protection and place a small volume of potassium chloride solution in a spotting tile
- Add a few drops of bromine water
- Note observations in a table
- Repeat for the other pairs of solutions
Asthmatics = extra care to not breathe in any chemical fumes
What type of a reaction is a halogen displacement reaction
Redox reaction
What happens to the halogen that displaces the other one
It gains electrons so it’s reduced
Cl2 + 2e- —> 2Cl-
What happens to the halogen displaced
It loses electrons so it’s oxidised
2Br- —> Br2 + 2e-
What kind of solutions and compounds do hydrogen halides form
Acidic solutions
Covalent compounds
Where is Group 0 found and what are they also called and why?
They are found on the right and called noble gases because they only take part in very few reactions
What are group 0 and what state are they at RTM
They are non metals and colourless gases at room temperature
What is group 0 so unreactive?
They have a complete outer shell of electrons so they don’t have a tendency to gain or lose electrons to form ions fair to share electrons to form molecules in solutions.
How many electrons does Group 0 have in their outer shell
They have 8 except for helium which has 2