Science (Chemistry) #2

• How many electrons does silicon have?

  14 electrons
• What is the electron structure for a sulphur atom?

  2, 8, 6
• What is the electron structure for a magnesium atom?

  2, 8, 2
• How many electrons are in the outer shell of a boron atom?

  3 electrons
• How many electrons are in the outer shell of a phosphorous atom?

  5 electrons
• How many electrons are in the outer shell of a sodium atom?

  1 electron
• An element has three electrons in the outer shell. What group is it in?

  Group 3
• How many electrons are in the outer shell of a gallium atom?

  3 electrons
• In terms of electrons, what do group 1 elements have in common?

  1 electron in outer shell
• In terms of electrons, what do group 7 elements have in common?

  7 electrons in outer shell
• Write a definition for an isotope.

  Same number of protons, different number of neutrons
• What does 'abundance' mean in chemistry?

  Amount
• Which element is more reactive, lithium or sodium?

  Sodium
• Which Group 7 element is more reactive, chlorine or bromine? Explain why.

  Chlorine, as it gains one electron more easily
• What is a trend?

  A pattern in chemical/physical properties
• State the trend in reactivity of the alkali metals down Group 1.

  Increases
• What element is the most reactive in Group 1 (alkali metals)?

  Francium
• State the trend in the melting points of the alkali metals down the group.

  Decreases (down the group)
• When alkali metals react with water, they fizz giving off a gas. Name this gas.

  Hydrogen
• What colour will universal indicator go if alkali metals are added to water?

  Purple (the solution produced is an alkali)
• Balance the equation: Li (s) + H₂O (l) → LiOH (aq) + H₂(g).

  2Li (s) + 2H₂O (l) → 2LiOH (aq) + H₂(g)
• Balance the equation: K (s) + H₂O (l) → KOH (aq) + H₂(g).

  2K (s) + 2H₂O (l) → 2KOH (aq) + H₂(g)
• State the compound name for LiOH.

  Lithium hydroxide
• What does the state symbol (s) mean?

  Solid
• What does the state symbol (l) mean?

  Liquid
• What does the state symbol (g) mean?

  Gas
• What does the state symbol (aq) mean?

  Aqueous - dissolved in water
• Complete: Lithium + Oxygen → ?

  Lithium Oxide
• State the chemical name for the compound, KOH.

  Potassium hydroxide
• What type of compounds do alkali metals form with non-metals?

  Ionic
• Explain why potassium is more reactive than lithium.

  Outer shell further away from nucleus in potassium, less attraction of outer shell electrons from nucleus, more shielding
• Name this compound, NaCl.

  Sodium Chloride
• Name this compound, CaCl₂.

  Calcium Chloride
• Name this compound, CaCO₃.

  Calcium Carbonate
• Name this compound, K₂SO₄.

  Potassium Sulfate
• How many atoms are in the compound: H₂SO₄?

  7 atoms
• What is the most reactive halogen (Group 7)?

  Fluorine
• What is the trend in reactivity in the halogens (Group 7)?

  More reactive up the group
• What is a displacement reaction?

  Reaction where more reactive element takes the place of a less reactive element in a compound
• Explain why the following reaction does not proceed: KBr (aq) + I₂ (s).

  Iodine is less reactive than bromine, so cannot displace it