alkali metals and the halogens and the noble gases

Question 1

what elements are in the noble gases - group 0

Answer 1

helium
neon
argon
krypton
xenon
radon

Question 2

name some uses of the noble gases

Answer 2

helium:
used in party balloons, weather balloons and air ships because it is low density and is lighter than air so it will float

neon:
emits light when current passes through it
advertisement signs

argon:
light bulbs, unreactive so the bulb can get very hot

Question 3

why are the noble gases unreactive?

Answer 3

they all have a full outer shell of electrons

Question 4

what elements are in the group 1?

Answer 4

lithium 
sodium
potassium
rubidium
caesium

Question 5

name some properties of the alkali metals group 1

Answer 5

soft
low density
very reactive

Question 6

what is the word and symbol equation for the alkali metals reaction with oxygen?

Answer 6

EG- sodium + oxygen –> sodium oxide

EG- 4Na + o2 –> 2 Na2O

Question 7

what colours does the flame of a Bunsen burner turn with the alternative reaction of the alkali metals and oxygen?

Answer 7

lithium - red
sodium - yellow-orange
potassium - lilac

Question 8

what happens when lithium reacts with water? what is seen, symbol and word equation.

Answer 8

fizzes and floats on the surface, turns U.I purple

word equation:
lithium + water –> lithium hydroxide + hydrogen

symbol equation:
2Li + 2 H2O –> 2LiOH + H2

Question 9

what happens when sodium reacts with water? what is seen, symbol and word equation.

Answer 9

fizzes and floats to the surface, turns U.I purple
turns into a molten ball

word equation:
sodium + water –> sodium hydroxide + hydrogen

symbol equation:
2Na + 2 H2O –> 2NaOH + H2

Question 10

what happens when potassium reacts with water? what is seen, symbol and word equation.

Answer 10

fizzes and floats to the surface, turns U.I purple
catches fire with a lilac flame

word equation:
potassium + water –> potassium hydroxide + hydrogen

symbol equation:
2K + 2 H2O –> 2KOH + H2

Question 11

why are the alkali metals stored under oil?

Answer 11

to keep them from reacting with oxygen and moisture in the air

Question 12

what happens to the melting points of the alkali metals down the group?

Answer 12

decrease

Question 13

what happens to the hardness of the alkali metals down the group?

Answer 13

decrease

Question 14

what happens to the reactivity of the alkali metals down the group?

Answer 14

increase

Question 15

what safety precautions must be taken when reacting the alkali metals with water?

Answer 15

safety glasses
safety screen
small piece of metal
handle metal with tweezers

Question 16

why are group 1 called the alkali metals?

Answer 16

they all form a alkaline solution when they react

Question 17

what is the test for hydrogen?

Answer 17

place a lit splint over the gas

popping sound with be heard if gas is present

Question 18

why do alkali metals get more reactive down the group?

Answer 18

they want to lose the outer most electron, the easier it is to do this the more reactive they are. down the group there is greater shielding as the electron is further away. the effective nuclear charge decreases and electron is lost easier

Question 19

what happens to the melting point down group 7, the halogens?

Answer 19

increases

Question 20

why does reactivity decrease down the group?

Answer 20

they need to gain 1 electron, the harder it is for the element to gain one electron, the less reactive it is. the outer most electrons are further away from the effective nuclear charge down the group and there is more shielding from inner orbitals, this makes the nuclear charge less effective at gaining an electron.

Question 21

name some uses of the halogens

Answer 21

chlorine:
added to drinking water, swimming pools and plastics because its poisonous and kills bacteria

iodine:
antiseptic because it kills bacteria

Question 22

what colours are the halogens in a displacement reaction?

Answer 22

fluorine - pale yellow, gas
chlorine - yellow/ green, gas
bromine - orange/ brown, liquid
iodine - grey/ black, solid

Question 23

word and symbol equation for alkali metal reacting with halogens

Answer 23

sodium + fluorine –> sodium fluoride

Na + Cl2 –> 2KCl

Question 24

what is a displacement reaction?

Answer 24

when a more reactive element displaces a less reactive element from its compound

Question 25

what happens when group 7 elements react with iron?

Answer 25

fluorine + iron –> iron(111) fluoride - no heat is required
F2 + Fe –> FeF3

chlorine + iron –> iron (111) chloride - heated fiercely, iron glows brightly
Cl2 + Fe –> FeCl3

bromine + iron –> iron (111) bromide - heated fiercely but glows less than chlorine
Br2 + Fe –> FeBr2

Question 26

why does displacement provide better evidence for decreasing reactivity?

Answer 26

because they compete during displacement

Question 27

what is the flame test and what does it determine?

Answer 27

place a small amount of compound on Bunsen burner flame

determines first name of the compound

Question 28

what colours do the flames turn?

Answer 28

lithium - red flame
sodium - yellow/orange flame
potassium - lilac flame 
barium - apple green flame 
calcium - brick red flame

Question 29

what is the silver nitrate test and what does it determine?

Answer 29

add Nitric acid followed by silver nitrate to the compound

it determines the last name of the compound

Question 30

what colours do the precipitate form?

Answer 30

chloride - white ppt
bromide - cream ppt
iodide - yelloe ppt