OCR alevel chemistry module 3

• What historical significance does the periodic table hold?

  It is arguably the most important bit of scientific development ever
• How were elements ordered in the 1800s?

  They were ordered according to atomic mass
• What do group 2 elements form when they react?

  Plus 2 ions
• What is the electron configuration ending for all group 2 metals?

  They all end in s2
• What did Döbereiner notice about the elements he grouped into triads?

  He noticed that elements in a triad had similar characteristics
• Which elements are mentioned as group 2 metals in the video?

  Beryllium, magnesium, and calcium
• How does the atomic radius change as you go down group 2?

  The atomic radius increases
• Why does the atomic radius increase down group 2?

  Extra electron shells are added as you go down the group
• What happens to the first ionization energy as you go down group 2?

  It decreases
• What is the relationship between ionization energy and reactivity in group 2 elements?

  As ionization energy decreases, reactivity increases
• What causes the decrease in ionization energy down group 2?

  Increased shielding and distance of outer electrons from the nucleus
• What do group 2 metals react with water to form?

  Metal hydroxides and hydrogen gas
• How does the reactivity of group 2 metals with water change down the group?

  Reactivity increases as you go down the group
• Which group 2 metal does not react with water?

  Beryllium
• How does magnesium react with cold water compared to steam?

  It reacts slowly with cold water and vigorously with steam
• What is formed when magnesium burns in oxygen?

  Magnesium oxide
• What is the oxidation number of magnesium in magnesium oxide?

  Plus two
• What happens to the oxidation number of oxygen when it forms magnesium oxide?

  It decreases from zero to minus two
• What do group 2 oxides form when they react with water?

  They form bases
• What was a limitation of Newlands' law of octaves?

  It broke down when some transition metals did not fit the pattern
• What is the ionic equation for the reaction of strontium oxide with water?

  SrO + H2O → Sr(OH)2
• How does the solubility of hydroxides change down group 2?

  They become more soluble as you go down the group
• What is the role of group 2 oxides and hydroxides in neutralization reactions?

  They can neutralize acids
• Who is credited with creating the current periodic table in 1869?

  Dmitri Mendeleev
• What is an example of a neutralization reaction involving calcium oxide?

  Calcium oxide reacts with an acid to form a salt and water
• What is the use of calcium hydroxide in agriculture?

  It is used to neutralize acidic soils
• How is magnesium hydroxide used in medicine?

  It is used to neutralize excess stomach acid
• What is the purpose of the slides mentioned in the video?

  The slides are for revision and can be purchased for use with notes.
• What is the general equation for neutralization reactions involving acids and bases?

  H⁺ + OH⁻ → H₂O
• Which group of the periodic table do halogens belong to?

  Halogens make up group 7 of the periodic table.
• What is the state of group 2 oxides at room temperature?

  They are white solids
• What was a significant feature of Mendeleev's periodic table?

  He left gaps for undiscovered elements
• What should you check when writing equations for reactions involving group 2 compounds?

  You should check the state symbols
• How did Mendeleev's approach differ from Newlands' in organizing elements?

  Mendeleev grouped elements by similar chemical properties and left gaps, while Newlands ordered them by atomic mass without gaps
• What can viewers do if they want a copy of the slides used in the video?

  They can click on the link in the description box
• What is the electron configuration of fluorine?

  The electron configuration of fluorine is 1s$^2$ 2s$^2$ 2p$^5$.
• What physical state is chlorine at room temperature?

  Chlorine is a pale green gas at room temperature.
• What is the importance of understanding group 2 elements in chemistry?

  They play a significant role in various chemical reactions and applications
• What is the physical state of iodine?

  Iodine is a gray solid.
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