Topic 6 - groups in the periodic table Flashcards
Properties of alkali metals
- soft
- relatively low melting points
Explain why some elements can be classified as alkali metals
(group 1), halogens (group 7) or noble gases
(group 0), based on their position in the periodic table
Alkali - because when they react with water it forms alkalies , elements in group 1
Noble gases- any elements that make up group 8
Halogens- group 7 , 7 outer electrons
Describe the reactions of lithium, sodium and potassium with
water
- hydrogen gas is produced
- lithium reacts fairly slowly , fizzing
- potassium reacts violently , immediately bursting into flame
Describe the pattern in reactivity of the alkali metals, lithium,
sodium and potassium, with water; and use this pattern to
predict the reactivity of other alkali metals
The reactivity of group 1 elements increases as you go down the group because: the atoms become larger. the outer electron becomes further from the nucleus. the force of attraction between the nucleus and the outer electron decreases.
Recall the colours and physical states of chlorine, bromine and
iodine at room temperature
Chlorine - is a pale green gas at room temperature
Bromine - is an orange liquid
Iodine - grey solid
Describe the pattern in the physical properties of the halogens,
chlorine, bromine and iodine, and use this pattern to predict
the physical properties of other halogens
Chlorine -chlorine is fairly reactive , poisonous
Bromine -poisonous
Iodine- grey solid which gives of purple vapour when heated
You can use the trends of physical properties from chlorine and iodine to predict the properties of halogens , for example the melting point increases down the group and the colours of halogens get darker
Describe chemical test for chlorine
You can see if the gas is chlorine by holding a piece of damp blue litmus paper over it. If chlorine is present then the litmus paper would be bleached , turning it white. It may also turn red for a moment because the solution of chlorine is acidic.
Describe the reactions of the halogens, chlorine, bromine and
iodine, with metals to form metal halides, and use this pattern
to predict the reactions of other halogens
Halogens will react vigorously with some metals to form salts called metal halides ,halogens higher up in group 7 are more reactive because they can attract the outer electron of the metal more easily.
Recall that the halogens, chlorine, bromine and iodine, form
hydrogen halides which dissolve in water to form acidic
solutions, and use this pattern to predict the reactions of other
halogens
Halogens can also react with hydrogen to form hydrogen halides .
Hydrogen halides are soluble and the can dissolve in water to form acidic solutions. (e.g hydrochloric acid)
Since they have the same number of electrons on the outer shell you can predicts they have similar properties.
Describe the relative reactivity of the halogens chlorine,
bromine and iodine, as shown by their displacement reactions
with halide ions in aqueous solution, and use this pattern to
predict the reactions of astatine
More reactive elements are able to displace the less reactive elements .
- Halogen displacement reactions are redox reactions
Explain why these displacement reactions are redox
reactions in terms of gain and loss of electrons,
identifying which of the substances are oxidised and
which are reduced
They are redox reactions because oxidation and reduction happen at the same time.
O I L R I G
Explain the relative reactivity of the halogens in terms of
electronic configurations
The higher we go up in the periodic table in group 7 the more reactive they are . This means fluorine is very reactive , however iodine has its outer electron shell further away from the nucleus making attraction weaker.
Explain why the noble gases are chemically inert, compared
with the other elements, in terms of their electronic
configurations
because they have complete outer shells , so they have no tendency in gaining or losing electrons
Explain how the uses of noble gases depend on their inertness,
low density and/or non-flammability
Inertness- they dont take part in any chemical reactions because of full outer shells
Low density- because particles in gases are widely
spread
Non flammable - because out full outer electron shell
Describe the pattern in the physical properties of some noble
gases and use this pattern to predict the physical properties of
other noble gases
- boiling points increase as you go down , because atoms get larger so inter molecular forces get stronger , more energy is needed to overcome these forces
