C4 Flashcards
(33 cards)
Physical properties of Group 1 metals
- Low melting and boiling points
- Low density
- Very soft
- Shiny when freshly cut
- Good electrical conductors
Reactions of Group 1 metals (in terms of electrons)
- They all have one outer shell electron.
- They readily lose the outer shell electron to for a 1+ ion. (They are very reactive)
- Further down group one you go the more reactive the metal is as the outer electron is further from the nucleus so there is less attraction between the electron and the nucleus so it is lost more easily.
Trends of Group 1 metals
- Further down you go the more reactive.
- Further down you go their density increases.
- Further down you go their melting and boiling point decreases (opposite to reactivity)
Physical properties of Group 7 elements (halogens)
- Brittle
- Non-metal
- Poor conductors of electricity
- Diatomic
At room temperature, what do Group 7 elements exist as?
- Flourine: Pale yellow gas
- Chlorine: Green gas
- Bromine: Orange-brown liquid
- Iodine: Shiny grey-black crystalline solid that sublimes to form a purple vapour.
Trends of halogens
- Further down you go their density increases.
- Further down you go, reactivity decreases.
- Further down you go, melting and boiling points increase.
Reactions of halogens (in terms of electrons)
- The further down Group 7 you go, the more energy levels there are meaning there is more distance between the nucleus and the electron that will form the 1- ion, so the forces of attraction are less.
Halogen displacement reactions.
- Cl2 + 2KBr > Br2 + 2KCL
- if a halogen is higher than the halogen in the compound (KBr), then it will displace it, if it is not higher, nothing will happen.
Properties of noble gases (Group 0/8)
- Unreactive due to their full outer shell.
- Monatomic
- Low boiling point due to their weak forces of attraction.
Trends as you go down Group 0.
- Boiling point, melting point increases.
- Density increase.
Transition metals physical properties.
Typical metallic properties e.g.,
- Shiny when freshly cut
- Hard and strong
- Malleable
- Good conductors of heat and electricity
- High density
- Coloured ionic compounds - e.g. Fe 2+ ions are light green
Transition metals vs. Group 1 metals (physical properties)
Transition metals are:
- Stronger, harder
- Higher densities
higher melting points except mercury
Other transition metal properties
- Good catalysts - e.g. Iron is a catalyst in the Haber process.
- Relatively unreactive, or react very slowly.
Reactivity series (in order)
Potassium, sodium, calcium, magnesium, aluminium, zinc, iron, tin, lead, hydrogen, copper, silver, gold, platinum
Metal displacement reactions
Essentially the same principle as halogen displacement reactions, if a metal is higher in the reactivity series than the metal in the compound, it will displace it.
CuSO4 + Fe > FeSO4 + Cu (iron is higher than copper)
How can you tell the reactivity of metals when they react with acids?`(practical)
- Add 2 cm3 of dilute HCl to a test tube, add the metal and note the rate of bubbles produced (hydrogen), the faster the rate, the more reactive the metal is.
Describe the test for chlorine gas.
Hold a damp piece of blue litmus paper near the gas.
If the gas is chlorine, it will turn red and then bleach to become white.
Describe the test for oxygen gas.
Place a glowing splint near the gas, if it relights, oxygen is present.
Describe the test for hydrogen gas.
Place a lit splint near the gas, if a squeaky pop noise is made, hydrogen is present. (The noise is hydrogen burning with atmospheric oxygen to form water)
Describe the test for carbon dioxide gas.
Pump the gas through limewater, if the gas is carbon dioxide, it will go from clear to cloudy.
(This happens as the calcium hydroxide and carbon dioxide reacts to form a white precipitate of calcium carbonate).
Describe how to carry out a flame test.
Dip a nichrome wire loop into HCl to clean it, then dip it into the sample of metal compound and place on the flame, a coloured flame will appear.
(This is because, heated metal ions jump energy levles when heated, when they return to their original energy level light is transferred as radiation).
Flame test colours for Li, Na, K, Ca, Cu2+
Lithium - Red Sodium - Yellow Potassium - Lilac Calcium - Orange - red Copper 2+ - Green-blue
Describe how to carry out a hydroxide precipitate test. What does it test for?
Tests for cations.
React the metal with sodium hydroxide (not other metal hydroxides as most metal hydroxides are insoluble)
A coloured precipitate will be produced to help identify.
Colours of different hydroxide precipitates. Fe 2+, Fe 3+, Cu 2+, Ca, Zn. How do you tell the difference between zinc hydroxide and calcium hydroxide.
Iron (II) - Green Iron (III) - Orange-brown Copper (II) - Blue Calcium - White Zinc - White - add excess NaOH, zinc will dissolve and turn colourless.
