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  1. The Periodic Table
  2. /Chemistry
  3. /Patterns Across Periods and Down Groups
Chapter 9 · Part 2 of 4The Periodic Table
← Previous part: From Triads to the Modern TableNext part: Families of Elements and Predictions →
High School (9–10)GeneralThe Periodic Table › Periodic TrendsStructure of the Atom › Electronic Configuration and ValencyFree course

Patterns Across Periods and Down Groups

Why does carbon make four bonds and oxygen two? Why is a sodium atom bigger than a chlorine atom? In this course we find the valency, the size, the metallic character and the oxides of the elements, and how they change across a period and down a group.

3 lessons, about 1 h 15 min3 simulations10 problems6 practice questionsPython in every lesson

StemPy LabCreated by StemPy Lab

Free

Every lesson is open to read. Enroll to keep your place in the course. No payment needed.

This course includes

  • 3 lessons, about 1 h 15 min
  • 3 simulations with sliders
  • 6 practice questions with new numbers each time
  • 3 Python programs to run
  • 10 problems with worked solutions
  • 2 Python labs
1 question set
  • 1 revision note
  • 1 test
    • Log in to save

    Course outline (3 lessons)

    1. 1
      Lesson 1about 25 min

      Valency and the position of an element

      The valency of an element is the number of electrons that it loses, gains or shares to get a full outer shell. It follows the outer electrons: it goes 1, 2, 3, 4, 3, 2, 1, 0 across a period, and it is the same for all of the elements of a group.

      1 simulation2 practice questions1 Python program3 problems1 Python lab
      Read the lesson
    2. 2
      Lesson 2about 25 min

      Atomic size and metallic character

      The atomic size decreases across a period, because the nucleus has more protons and it pulls the shells closer. It increases down a group, because each new period adds a shell. Metallic character is the tendency to lose electrons: it decreases across a period and increases down a group.

      1 simulation2 practice questions1 Python program4 problems1 Python lab1 question set
      Read the lesson
    3. 3
      Lesson 3about 25 min

      Gaining and losing electrons, and the oxides

      Across a period, the tendency to lose electrons falls and the tendency to gain electrons rises. Down a group, the tendency to lose electrons rises. The oxides of the metals on the left are basic, and those of non-metals on the right are acidic. Between them, aluminium oxide is amphoteric.

      1 simulation2 practice questions1 Python program3 problems1 note
      Read the lesson

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    Trends in the Periodic Table: Challenge Paper
    10 questions · 20 min
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    ← All Courses
    ← From Triads to the Modern TableFamilies of Elements and Predictions →
    More onThe Periodic Table › Periodic TrendsStructure of the Atom › Electronic Configuration and Valency

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