topic 6 periodic table groups

Question 1

why does group 1 have similar chemical properties

Answer 1

one outer electron so they have similar chemical properties

Question 2

physical properties of group 1

Answer 2

low melting points and boiling points
very soft

Question 3

alkali metals form what

Answer 3

ionic compounds. they lose their single outer electron so easily that sharing can’t happen, so they dont form covalent bonds

Question 4

when and why does reactivity increase in group 1

Answer 4

as you go down the periodic table, reactivity increases as the outer electron is more easily lost as it’s further from the nucleus so it’s less strongly attracted to the nucleus and less energy is needed to remove it

Question 5

group 1 reactions with cold water

Answer 5

react vigorously
reaction produces a hydrogen gas and a hydroxide of the metal (an alkali)

Question 6

sodium + water balanced equation

Answer 6

2Na + 2H2O -> 2NaOH + H2

Question 7

what happens when hydrogen is present

Answer 7

squeaky pop

Question 8

describe each of the alkali metals with water

Answer 8

lithium will move around the surface, fizzing furiously
sodium and potassium do the same, but also melt in the heat of the reaction
potassium gets hot enough to ignite a lilac flame from the hydrogen gas being produced

Question 9

why do group 7 elements have similar chemical properties

Answer 9

all have 7 electrons in their outer shell

Question 10

the halogens exist as what?

Answer 10

diatomic molecules e.g. Cl2 Bl2 I2

Question 11

what happens as you go down group 7?

Answer 11

the melting points and boiling points of the halogens increase. this means that at room temperature:
chlorine is a fairly reactive, poisonous green gas
bromine is a red brown liquid which gives off an orange vapour
iodine is a dark grey crystalline solid which gives off purple vapour

Question 12

what bond is group 7 halogens

Answer 12

covalent bond as they share an electron to gain a full outer shell

Question 13

how to predict properties of halogens further down group 7

Answer 13

melting points increase down the group
colours of halogens get darker down the group
so astatine (below iodine) would be a dark coloured solid at room temperature

Question 14

how to test for chlorine

Answer 14

damp blue litmus paper over the chlorine gas
chlorine will bleach the litmus paper, turning it white. it may also turn red for a moment (it’s acidic)

Question 15

why do elements become less reactive as you go down group 7?

Answer 15

harder to attract the extra electron to fill the outer shell when it’s further away from the nucleus

Question 16

what are metal halides

Answer 16

when halogens react with metals to form salts

Question 17

example of metal halide reaction

Answer 17

2Na + Cl2 -> 2NaCl

Question 18

example of hydrogen halide reaction

Answer 18

H2 + Cl2 -> 2HCl

Question 19

properties of hydrogen halides

Answer 19

soluble and can dissolve in water to form acidic solutions
HCl is hydrochloric acid in water

Question 20

what are halogen displacement reactions called

Answer 20

redox reactions

Question 21

why does the solution go orange when chlorine displaces bromine

Answer 21

the bromide ions are oxidised to bromine which turns the solution orange

Question 22

halogen displacement reaction example (they all follow the same pattern)

Answer 22

balanced: Cl2 + 2KBr —> Br2 + 2KCl

ionic equation: Cl2 + 2Br- —> Br2 + 2Cl-

Question 23

what colour solution is formed when chlorine and bromine displace iodine

Answer 23

brown solution

Question 24

halogen displacement reactions

Answer 24

chlorine displaces both bromine and iodine from salt solutions
bromine can’t displace chlorine, but it does displace iodine
iodine can’t displace chlorine or bromine

this shows a reactivity trend

we can predict that astatine, below iodine, would not displace iodine.

Question 25

what colour are group 0 elements at room temp

Answer 25

colourless

Question 26

what are the noble gases

Answer 26

inert and monatomic (made up of single atoms not molecules)

Question 27

do noble gases catch fire easily?

Answer 27

no

Question 28

what can noble gases be used for

Answer 28

an inert atmosphere

argon does this in filament lamps since it’s non flammable, it stops the hot filament from burning away

flash photography used halogens to stop the flash filament from burning up during high temperature flashes

argon and helium can protect metals being welded as the inert atmosphere stops the hot metal reacting with oxygen

helium is used in airships and party balloons due to its lower density than air which causes them to float. its non flammable which is safer than hydrogen gas

Question 29

what happens when you go down group 0

Answer 29

boiling point, melting point and density all increase