Groups in The Periodic Table

• Which group are alkali metals?

  Group 1.
• Properties of alkali metals.

  Relatively low melting point, soft
• Why are they called alkali metals?

  Because they form alkaline solutions when they react with water.
• What are the products of lithium and water?

  Lithium hydroxide and hydrogen.
• reaction of sodium with water equation.

  2Na + 2H2O - 2NaOH + H2
• why should alkali metals be stored in oil?

  To prevent them reacting with water vapour and oxygen in the air.
• What would be observed when lithium reacts with water?

  Slowest reaction of the alkali metals. Bubbles of hydrogen produced. Doesn‘t melt (highest melting point of alkali metals).
• What would be observed when sodium reacts with water?

  Faster reaction than lithium, floats on the surface of water, bubbles of hydrogen causing sodium to whizz around on the surface, melts as energy given out is enough to meet sodium’s melting point.
• What would be observed when potassium reacts with water?

  More violent reaction than sodium, bubbles of hydrogen are produced which cause the potassium to whizz around on the surface if the water. Melts into a shiny ball, burns with a lilac flame.
• Why does reactivity increase going down group 1?

  The number of electron shells increases so thanks to electron shielding there is a weaker attraction between the nucleus and the outer electron that needs to be lost, so easier to form a cation.
• Which group are the halogens in?

  Group 7.
• What is the colour and state of chlorine at room temperature?

  Pale green gas.
• What is the colour and state of bromine at room temperature?

  Red-brown liquid.
• What is the colour and state of iodine at room temperature?

  Black solid.
• Why does melting/boiling point increase down group 7?

  The molecules get larger so there are more intermolecular forces to overcome, so more energy is required to break them.
• Chemical test for chlorine?

  Damp litmus paper placed into a test tube, turns red then bleached white by chlorine.
• What is produced when a halogen reacts with a metal?

  Metal halide salt.
• Equation for the reaction between bromine and sodium.

  Br2 + 2Na - 2NaBr
• Equation for the reaction between chlorine and calcium.

  Cl2 + Ca - CaCl2
• What do the ions of halogens end in?

  -ide
• Why does reactivity decrease down group 7?

  Reactivity decreases down Group 7 due to the increasing atomic radius, more electron shielding means it is harder to gain an electron to form an anion.
• What is formed when a hydrogen halide dissolved in water?

  An acidic solution, hydrogen ions dissociate, making the solution acidic.
• Reaction between hydrogen and chlorine.

  H2 + Cl2 - 2HCl
• When does a halogen displacement reaction occur?

  When a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide.
• Equation for the reaction between bromine and potassium iodide.

  Br2 + 2Kl - I2 + 2KBr
• What colours are the solutions of group 7 elements?

  Chlorine water - colourless

  Bromine water - orange

  Iodine solution - brown
• Why are halogen displacement reactioms redox reactions?

  The halide ion is oxidised to form a halogen atom and the halogen is reduced to from a halide ion.
• Half equations for chlorine and potassium bromide reaction.

  Overall: Cl2 + 2KBr - Br2 + 2KCl

  Reduction: Cl2 + 2e- - 2Cl-

  Oxidation: 2Br- - Br2 + 2e-
• What group are noble gases?

  Group 0.
• What properties of helium makes it suitable for use in balloons.

  It is less dense than air and does not burn.
• Why is argon used to fill electric light bulbs?

  Chemically inert so will not react when the light bulb gets hot, it is non-flammable.
• Why does boiling point increase down group 0?

  The Mr increases so there are more intermolecular forces between atoms.
• Trend in density in group 0.

  Increases down the group.