SC4 - The Periodic Table ✓ Flashcards Preview

Edexcel GCSE Chemistry COPY > SC4 - The Periodic Table ✓ > Flashcards

Flashcards in SC4 - The Periodic Table ✓ Deck (9)
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SC4a - How did Medeleev organise his periodic table?

By increasing atomic mass


SC4a - What two things did Mendeleev do to the order of elements in his table that made it more sucessful than others?

  • Left gaps for certain elements
  • Swapped elements around
  • He did this because he realised a trend in the chemical and physical properties in relation to the groups of elements


SC4a - How did Mendeleev predict the property of elements such as eka-alluminium (now known as gallium)

He identified the trend in properties down a group and used this information to estimate the properties of undiscovered elements


SC4b - Why does (in the modern periodic table) Tellerium come before Iodine despite having a greater mass number?

  • Iodine exists mostly as Iodine-127
  • Tellerium has many isotopes ranging from Te-126 to Te-130
  • This means Tellerium's Ar is ~128
  • This proves one reason why it is more reliable to order elements by increasing atomic number than by mass number


SC4b - How is the atomic number related to energy given off in x-rays when electrons are fired at an element?

  • The square root of the energy given off is directly proportionate to the atomic number.
  • This realisation proved the idea of protons and that the atomic number is the number of protons in an atom.


SC4b - What are the four main features of the modern periodic table?

  • Elements in a period are in order of increasing atomic number
  • Elements with similar properties are in the same group
  • Non-metals are on the right and metals are on the left
  • The Iodine Tellerium pair reversal is explained


SC4c - How do atoms store electrons?

  • Atoms have electrons in orbits of electron shells around the nucleus
  • The first shell holds up to 2 electrons
  • The second and third shell holds up to 8 electrons


SC4c - How do you work out the electron configuration of an element? Use Chlorine (Atomic number 17) as an example

  • Atomic number 17 means 17 protons and thus 17 electrons. 1
  • 7-2 is 15, 15-8 is 7, 7-8 is a negative number so there are 2 in the first shell,8 in the second and 7 in the third 2.8.7


SC4c - How does the electron configuration of an atom relate to its position on the periodic table in terms of group and period?

  • The total amount of electron shells will be the period it is in.
  • The number of electrons in its outermost shell is equal to the group that it's in.