topic 6 - exam qs

• Lithim, sodium and potassium are what elements?

  Alkali metals
• When sodium is added to cold water, it forms a molten ball which floats on the surface of the water. Explain why

  When sodium and water react, it is exothermic meaning it produces heat. Sodium has a low melting point and it has a density less than water which explains why the molten ball floats.
• Sodium and potassium react with cold water to give similar products. Sodium = 2.8.1, potassium = 2.8.8.1 Explain the SIMILARITES in the way sodium and potassium react with cold water considering their reactions and their electronic configurations.

  they are both in the same group (alkali metals) meaning they have the same number of outer shell electrons so they react in a similar way. They both give off hydrogen when reacted with water and both produce a hydroxide (alkaline) solution.
• Sodium and potassium react with cold water to give similar products. Sodium = 2.8.1, potassium = 2.8.8.1 Explain the DIFFERENCES in the way sodium and potassium react with cold water considering their reactions and their electronic configurations.

  Potassium is more reactive as the outer electrons furthest from the nucleus are further away from the nucleus than in sodium meaning it has less attraction and is more easily lost. Potassium will also catch on fire, causing a lilac flame.
• What are some physical properties of lithium, sodium and potassium (group 1)?

  They are good conductors of heat and electricity, the freshly-cut metals are shiny, solid at room temperature, low melting point, low boiling point, soft
• A small piece of potassium is added to water. What would you see?

  Potassium causes fizzing and it will float. Potassium forms a ball and decreases in size. A lilac flame is caused.
• Why is argon used in filament lamps?

  It is inert
• Metals are malleable, why?

  Atoms are in layers and the layers can slide over each other.
• Give an example of 2 group 1 metals and 2 transition metals:

  Potassium, caesium and copper, iron
• Describe the structure of metals in terms of particles present in their structures:

  Metals are made up of cations in a regular arrangement surrounded by a sea of delocalised electrons
• What would you see when a small piece of sodium is added to water?

  Fizzing, sodium melts and becomes a ball shape, becomes smaller, it floats
• Chlorine reacts with potassium bromide to form bromine and potassium chloride. What is this reaction?

  Displacement
• Chlorine reacts with potassium bromide to form bromine and potassium chloride. What is the colour of the mixture at the end of the reaction?

  Orange
• Chlorine reacts with an element X to form a solid chloride, it is dark red. Where is element X most likely to be in the periodic table?

  Transition metals
• To join 2 pieces of metal by welding, they must be melted together. State why a high temperature has to be used?

  Metals have a high melting point so a lot of energy is needed to overcome metallic bonds
• Some metals react with halogens. Iron reacts with bromine, Br2 , to form iron(III) bromide, FeBr3 . Write the balanced equation for this reaction.

  2 Fe + 3 Br2 -> 2 FeBr3
• At toom temperature, what is iodine?

  A grey solid
• Use the info in the table to explain the order of reactivity of the 3 halogens:

  Chlorine is more reactive than bromine which is more reactive than iodine. This is known because chlorine and bromine displace iodine from iodide, for bromine this is the only displacement whereas chlorine displaces bromine from bromide also. Iodine doesn't displace anything, showing the order of reactivity.

  
• When iron reacts with bromine, bromide ions are formed. Explain the type of reaction bromine atoms undergo when they are converted to bromide ions.

  Bromine atoms are reduced because electrons are gained to form bromide ions.
• State a hazard associated with chlorine gas

  It is poisonous or toxic
• How do you test for chlorine gas?

  Damp blue litmus paper will turn red then it will bleach and turn white
• State a use for chlorine:

  Medicine, bleach