Topic 6 - Groups of the Periodic Table Flashcards
Name for the group 1 elements
Alkali metals
Name for the group 7 elements
Halogens
Ion, definiton
An atom, or group of atoms, that have gained or lost an electron
Molecule, definition
A group of atoms that are chemically joined
Name for the group 0 elements
Noble gases
A column on the periodic table
group
A row on the periodic table
period
The group number provides this information about an atom…
The number of electrons in the outer shell
The period number provides this information about an atom…
The number of electron shells
The electronic configuration of a sodium atom
2,8,1
The electronic configuration of a sodium ion
2,8
The electronic configuration of a lithium atom
2,1
The electronic configuration of a lithium ion
2
The electronic configuration of a chlorine atom
2,8,7
The electronic configuration of a chloride ion
2,8,8
Reasons for including hydrogen in group 1 of the periodic table
- It has one electron in its outer shell
Reasons for NOT including hydrogen in group 1 of the periodic table
- It is a non-metal
Group 1 elements form ions with a charge of..
1
Group 7 elements form ions with a charge of..
-1
Properties of the group 1 metals
- Soft - they can be cut with a scalpel
Colour of fluorine
yellow
Colour of chlorine
yellow-green
Colour of bromine
red-brown
Colour of iodine, in the solvent hexane
purple
Colour of iodine, in the solvent water
brown
Reason why the group 1 metals are stored under mineral oil
They would react with the water in the atmosphere
Reason why lithium turns black when exposed to air
It reacts with nitrogen in the air to make a layer of lithium nitride on the surface of the metal
Lithium reacts with water to make…
Lithium hydroxide and hydrogen gas
Sodium reacts with water to make…
Sodium hydroxide and hydrogen gas
Potassium reacts with water to make…
Potassium hydroxide and hydrogen gas
pH of potassium hydroxide solution
12 to 14
Colour of potassium hydroxide solution with universal indicator
Dark blue to purple
State symbol of hydrogen
(g)
State symbol of sodium
(s)
State symbol of water
(l)
State symbol of potassium hydroxide
(aq)
Atomic radius
Size of an atom, from the centre to the outermost electron
Ionic radius
Size of an ion, from the centre to the outermost electron
Aqueous
Soluble in water, has the state symbol (aq)
Describe the trend in reactivity of the group 1 elements
Reactivity increases as you descend the group
Describe the trend in reactivity of the group 7 elements
Reactivity decreases as you descend the group
Describe the trend in the melting points of the group 1 elements
Meting points decrease as you descend the group.
-
Describe the trend in the melting points of the group 7 elements
Meting points increase as you descend the group
State of fluorine at room temperature
gas
State of chlorine at room temperature
gas
State of bromine at room temperature
liquid
State of iodine at room temperature
solid
Explanation for the trend in melting points for the group 7 elements
- As you descend the group, the size of the diatomic molecules increases because the size of the atoms increases
Displacement reaction
Reaction in which one element replaces a similar element in a compound
Redox reaction
A reaction in which both reduction and oxidation take place.
Oxidation, in terms of electrons
Loss of electrons
Reduction, in terms of electrons
Gain of electrons
Ionic equation
An equation that shows only those ions or atoms that change in a chemical reaction. It ignores the spectator ions that do not take part.
Symbol equation
An equation that includes the spectator ions that do not take part in the reaction
In general, metal atoms are oxidised / reduced
Oxidised
In general, non-metal atoms are oxidised / reduced
Reduced
Halide ion
A negative ion formed when a halogen atom gains an electron
An element that is more reactive than iodine but less reactive than chlorine
Bromine
An element that is more reactive than bromine but less reactive than fluorine
Chlorine
An element that is more reactive than lithium but less reactive than potassium
Sodium
An element that is more reactive than sodium but less reactive than rubidium
Potassium
Chloride ions have a yellow-green colour
False. They are colourless.
In this reaction what is reduced? Explain your answer.
The equation: F2 + 2Br- > 2F- + Br2
- The fluorine atoms in the fluorine molecule are reduced because they gain electrons
In this reaction what is oxidised? Explain your answer.
The equation:
F2 + 2I- > 2F- + I2
The iodide ion is reduced because it loses electrons
Suggest 3 spectator ions that may have been excluded from this equation. Explain why they are not included.
The equation: Cl2 + 2Br > 2Cl + Br2
- Ions of lithium, sodium or potassium.
- They are not included because they do not take part in the reaction.
- They are neither oxidised nor reduced. They remain unchanged at the end of the reaction.
A colour change from yellow-green to brown
Suggest what would be observed in this reaction. Assume that the solvent is water.
Explanation for the trend in reactivity of the group 1 elements
- As you descend the group the atomic radius increases
Explanation for the trend in reactivity of the group 7 elements
1) - As you go up the group the atomic radius decreases (less electron shells).
2) - Therefore, the positively charged nucleus is closer to the outer electron of a neighbouring atom.
3) - Therefore, an electron is gained more easily.
4) - And the atom is more easily reduced.
The colour of a potassium flame
Lilac
State one similarity in the reactions between lithium, sodium and potassium with water
They are all exothermic and all involve fizzing
State one similarity in the reactions between lithium and potassium with water. Explain your answer.
- Potassium produces a lilac flame whereas lithium produces no flame.
- This is because the reaction between potassium and water is more exothermic and sufficient heat energy is produced to ignite the hydrogen gas.
Colour of potassium bromide solution
Colourless
What is observed when chlorine is bubbled through potassium bromide solution
The solution changes colour from colourless to orange
What is observed when chlorine is bubbled through potassium iodide solution
The solution changes colour from colourless to brown
Formula of lithium hydroxide
LiOH
Formula of sodium hydroxide
NaOH
Formula of potassium hydroxide
KOH
Formula of rubidium hydroxide
RbOH
Group 1 hydroxides are acidic / alkaline / neutral
alkaline
What can you observe when lithium reacts with water?
Fierce bubbling on surface of water
What can you observe when sodium reacts with water?
Melts into a ball and fizzes on the surface
What can you observe when potassium reacts with water
Bursts into flames and flies around surface
Properties of group 7 elements (3)
- do not conduct electricity
- Brittle and crumbly solids
- Poisonous with a strong odour
Halogens react with metals to form…
metal halides (salts)
Halogens react with hydrogen to form…
Hydrogen halides
Test for chlorine gas
Turns damp litmus paper red and then bleaches white
What happens in a displacement reaction?
A more reactive metal will displace a less reactive metal from a solution of its salt
Properties of noble gases (7)
- colourless
- very low melting and boiling points
- Poor conductors of heat and electricity
- Inert
- Monatomic
- Low densities
- Not flammable
Give a use of helium and why
Zeppelins because of its low density and it isn’t flammable
Give a use of neon and why
Used in signs because it glows red-orange when electricity is passed through it
Give a use of argon and why
Used in filament lamps because it is inert and not flammable
Why does melting point increase down group 7?
More shells, more electrons, more IMFs, more energy needed to allow a change of state to occur
How can you improve the sodium thiosulfate practical?
Use a light spectrometer rather than judging when cross disappears
