Year 8 Science · Unit 2 · Lesson 13

Groups and Periods

Foundation Worksheet

Name

Date

Class

Learning Goals

Define group and period, and name groups 1, 17 and 18.
Find an element from its group and period, its name or its atomic number.
Use class quiz results to explain the most common mistake when locating elements.

Warm Up

Figure 1 is a strip of the periodic table. The ten middle groups are left out. You will use it for the rest of this sheet.

Figure 1. Part of the periodic table (symbol and atomic number)

Period	Group 1	2	13	14	15	16	17	18
1	H 1							He 2
2	Li 3	Be 4	B 5	C 6	N 7	O 8	F 9	Ne 10
3	Na 11	Mg 12	Al 13	Si 14	P 15	S 16	Cl 17	Ar 18
4	K 19	Ca 20	Ga 31	Ge 32	As 33	Se 34	Br 35	Kr 36

Source: modern periodic table, with groups numbered the IUPAC way.

Fill the gap

Choose the correct word from the word bank. Two words will not be used.

noble gases period isotopes halogens atomic number group mass alkali metals

A vertical column of the periodic table is called a . A horizontal row is called a . The elements are placed in the table in order of their . Group 1 elements, such as sodium, are the . Group 17 elements, such as chlorine, are the , and group 18 elements are the very unreactive .

Your Turn

Locate it

Use Figure 1 to complete the table.

You are given	Element name	Group	Period
Chlorine	chlorine
Group 2, period 3		2	3
Atomic number 7
Symbol K

Go Deeper

Read the data

A locating quiz

28 Year 8 students answered four locating questions.

Table 1. Results of a four-question locating quiz (28 students)

Question	Correct answer	Students correct	Most common wrong answer
A. Give the group and period of sodium.	Group 1, period 3	15	Group 3, period 1
B. Which element has the symbol K?	Potassium	17	Krypton
C. Which element has atomic number 8?	Oxygen	25	Nitrogen
D. Which element is in group 1, period 2?	Lithium	22	Beryllium

Source: sample class results.

1. Which question did the fewest students get right? How many students got it wrong?

Recall 2 marks

2. In question B, many students wrote “krypton”. Use Figure 1 to explain why this answer is wrong, and give the correct symbol for krypton.

Apply 2 marks

Show What You Know

3. A student writes: “Lithium and sodium are in the same period, because they both react with water.” Explain what is wrong with this sentence. Use the words group and period, give the position of each element, and say what being in the same group tells you.

Analyse 4 marks

Answer Key (for teachers)

Fill the gap

group; period; atomic number; alkali metals; halogens; noble gases. Not used (2): isotopes, mass.

Locate it

Chlorine: group 17, period 3. Group 2, period 3: magnesium. Atomic number 7: nitrogen, group 15, period 2. Symbol K: potassium, group 1, period 4.

Read the data

1. Question A (15 of 28 correct), so 13 students got it wrong. [2 marks: 1 question, 1 number]

2. In Figure 1, K is in group 1, period 4, and that box is potassium. Krypton is in group 18, period 4, and its symbol is Kr. [2 marks: 1 K is potassium, 1 Kr]

Show What You Know

3. Marking guide (points expected): 1 they are in the same group, not the same period; 1 lithium is group 1, period 2 and sodium is group 1, period 3 (so they are in different periods); 1 elements in the same group have the same number of outer electrons (one each); 1 so they have similar chemical properties, which is why both react with water. [4 marks]

Common error to watch for: reversing group and period, as in quiz question A. Question A’s wrong answer swaps the two numbers; teach “group = column, period = row”.