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9th grade · Science · Unit 6 of 10

The Periodic Table

Groups, periods and patterns

What your child practices

Groups and periods, metals, non-metals and metalloids, alkali metals, halogens and noble gases, and how valence electrons and shells explain the patterns.

Maine Learning Results learning standard: HS-PS1-1 · patterns in the periodic table

How we explain it

Children can open this short lesson before they practice.

  1. Rows are periods; the number of electron shells gives the period.
  2. Columns are groups. In groups 1 and 2, the group is the number of valence (outer) electrons; for groups 13 to 18, add 10.
  3. Group 1: alkali metals; group 17: halogens; group 18: noble gases, which rarely react.

Example: Oxygen’s electrons are 2, 6. Which period and group is it in? 2 shells: period 2. 6 valence electrons: 6 + 10 = group 16. Answer: period 2, group 16

The Periodic Table in Maine

In the Maine Learning Results, this is unit 6 of 10 in 9th grade Science, after Photosynthesis & Respiration and before Chemical Change.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Maine Department of Education

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Which element is a metalloid?

    • chlorine
    • silicon
    • sodium
    • oxygen

  2. Question 2

    Aluminum has electrons arranged 2, 8, 3. Which period (row) is it in?

    answer box

  3. Question 3

    Group 1 elements, such as lithium, sodium and potassium (not hydrogen), are called the…

    • noble gases
    • alkaline earth metals
    • alkali metals
    • halogens

  4. Question 4

    Where are the metals found on the periodic table?

    • only on the far right
    • on the left and in the middle
    • only in the top row
    • metals are not on the table

  5. Question 5

    Hydrogen is in the top left of the periodic table, but it is not an alkali metal. Why?

    • It is a non-metal gas with different properties
    • It has no electrons
    • It is a noble gas
    • It is a liquid metal

  6. Question 6

    Which element has 2 electron shells and 8 valence electrons?

    • Aluminum
    • Magnesium
    • Neon
    • Sodium

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