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Chemistry Grade 6-8 Answer Key

Chemistry: Reading the Periodic Table: Groups and Periods

Identifying element locations using rows and columns

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Chemistry: Reading the Periodic Table: Groups and Periods

Identifying element locations using rows and columns

Chemistry - Grade 6-8

Instructions: Use a periodic table to answer each question. Read each problem carefully and show your work or reasoning in the space provided.
  1. 1

    On the periodic table, what is a period, and which direction does it run?

    Think of a sentence written across a page.

    A period is a horizontal row on the periodic table. Periods run from left to right.
  2. 2

    On the periodic table, what is a group, and which direction does it run?

    A group is a vertical column on the periodic table. Groups run from top to bottom.
  3. 3

    Find oxygen, O, on the periodic table. What period is oxygen in, and what group is oxygen in?

    First find the symbol O, then read the row and column numbers.

    Oxygen is in period 2 and group 16.
  4. 4

    Find sodium, Na, on the periodic table. What period is sodium in, and what group is sodium in?

    Sodium is in period 3 and group 1.
  5. 5

    Elements in the same group often have similar chemical properties. Explain why lithium, sodium, and potassium are placed in the same group.

    Look at the column that contains Li, Na, and K.

    Lithium, sodium, and potassium are placed in the same group because they are all in the same vertical column, group 1. Elements in the same group often behave in similar ways.
  6. 6

    Which elements are in period 2 from lithium to neon? Write their symbols in order from left to right.

    The elements in period 2 from left to right are Li, Be, B, C, N, O, F, and Ne.
  7. 7

    Carbon, nitrogen, and oxygen are all in period 2. What does this tell you about their location on the periodic table?

    A period is a row.

    Carbon, nitrogen, and oxygen are all in the same horizontal row. They are located across period 2 of the periodic table.
  8. 8

    Find chlorine, Cl, and bromine, Br. Are they in the same group or the same period? Explain your answer.

    Chlorine and bromine are in the same group, group 17. They are not in the same period because chlorine is in period 3 and bromine is in period 4.
  9. 9

    The noble gases are found in group 18. Name three noble gases and give their symbols.

    Look at the far right column of the periodic table.

    Three noble gases are helium, He, neon, Ne, and argon, Ar. Other correct examples include krypton, Kr, xenon, Xe, and radon, Rn.
  10. 10

    An element is located in period 3 and group 2. What is the element name and symbol?

    The element in period 3 and group 2 is magnesium, Mg.
  11. 11

    An element is located in period 4 and group 1. What is the element name and symbol?

    Find period 4 first, then move to the first column.

    The element in period 4 and group 1 is potassium, K.
  12. 12

    Compare calcium, Ca, and selenium, Se. Which element is in group 2, and which element is in group 16?

    Use the group numbers at the top of the columns.

    Calcium is in group 2, and selenium is in group 16.
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