groups in the periodic table

Question 1

Explain why some elements can be classified as alkali metals, halogens or noble gases based
on their position in the periodic table

Answer 1

Groups (columns) in the periodic table can be classified in specific groups as e.g. alkali metals, halogens or noble gases, because they have the same number of electrons in their outer shell (position in the periodic table determines this), therefore they have the same chemical properties

Question 2

Describe the reactions of lithium, sodium and potassium with
water

Answer 2

• lithium = move around the surface fizzing
• sodium and potassium = move around surface , fizzing , melt
• potassium = does all this but also can get hot enough to ignite the hydrogen gas being produced

Question 3

alkali metals are

Answer 3

• soft
• low melting points

Question 4

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

Answer 4

• as you go down group 1 the alkali metals get more reactive
• to predict look at what’s lower down in the group and that is what will be the most reactive

Question 5

Explain this pattern in reactivity of alkali metals in terms of electronic
configurations

Answer 5

• readily lose their single outer electron to form a 1 + ion with a stable electronic structure
• more readily a metal loses its outer electrons the more reactive it is
• have one outer electron

Question 6

recall the colours and physical states of chlorine, bromine and
iodine at room temperature

Answer 6

• chlorine = green gas
• iodine = dark grey crystalline solid which gives off a purple vapour when heated
• bromine = red - brown liquid which gives off an orange vapour

Question 7

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

Answer 7

• as you go down group 7 the melting and boiling points of the halogens increase
• as you go down the group the colours get darker as well
  ex predict astatine (below iodine) would be a dark coloured solid at room temp)

Question 8

Describe the chemical test for chlorine

Answer 8

damp blue litmus paper will bleach white if chlorine is present

Question 9

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

Answer 9

• halogens can react with metals to form metal halides
• halogens higher up in group 7 are react to form metal halides because they can attract the outer electron of the metal more easily
• since all halogens have the same number of electrons in their outer shells they all have similar reactions

Question 10

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

Answer 10

chlorine, bromine and iodine form hydrogen halides which are soluble (dissolve in water) to form acidic solutions
- since all halogens have the same number of electrons in their outer shells they all have similar reactions

Question 11

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

Question 12

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

Answer 12

these displacement reactions are redox reactions because because the halogens gain electrons (reduction) and the halide ions lose electrons (oxidation)

Question 13

Explain the relative reactivity of the halogens in terms of
electronic configurations

Answer 13

• reactivity decreases going down group 7
• a halogen atom only needs to gain one electron to form a 1 - ion with a stable electronic structure
• easier it is for halogen atom to attract an electron, the more reactive the halogen will be
• as you go down group 7 it gets harder to attract the extra electron to fill the outer shell when its further away from the nucleus (large atomic radius)

Question 14

Explain why the noble gases are chemically inert, compared
with the other elements, in terms of their electronic
configurations

Answer 14

• inert = don’t react with much at all
• they are chemically inert because they have a full outer shell of electrons 9dont easily give up or gain electrons)

Question 15

Explain how the uses of helium in airships and party balloons is dependent on its physical properties

Answer 15

• helium = airships and party balloons, - lower density than air
• so makes balloons float,
• also non flammable
• so makes it safer than hydrogen gas

Question 16

Describe the pattern in the physical properties of some noble
gases and use this pattern to predict the physical properties of
other noble gases

Answer 16

boiling and melting points and density all increase as you go down group 0

Question 17

Explain how the use of argon depends on its chemical properties

Answer 17

• argon = used in filament lamps
• as its non flammable and
• stops the filament burning away

Question 18

Explain how the properties of argon and helium can be used to protect metals being welded

Answer 18

• argon and helium = protect metals that are being welded,
• inert atmosphere
• stops hot metal
• reacting with oxygen