Lesson Notes By Weeks and Term - Senior Secondary 2

Periodic Table 2

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TERM׃ 1ST TERM

WEEK THREE

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:        

Subject: Chemistry

Topic: Periodic Table 2

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Discuss the properties of elements on the periodic table according to size.
  2. Discuss the properties of elements on the periodic table according diagonal relationship.
  3. Discuss the properties of elements on the periodic table according ionization and electron affinity.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S ACTIVITY

STEP 1

INTRODUCTION

The teacher discusses the properties of elements on the periodic table according size.

Students pay attention

STEP 2

EXPLANATION

He explains the properties of elements on the periodic table according diagonal relationship.

 

Students pay attention and participates

STEP 3

DEMONSTRATION

He discusses the properties of elements on the periodic table according ionization energy and electron affinity.

 

Students pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a summarized note on the board

The students copy the note in their books

 

NOTE

PERIODIC TABLE 2

Properties of elements on the periodic table

According to size

The size of an atom, or its atomic radius, generally follows certain trends on the periodic table:

  1. Atomic Radius: Increases down a group (from top to bottom) because of additional energy levels.
  2. Atomic Radius: Decreases across a period (from left to right) due to increased effective nuclear charge.
  3. Ionic Radius: Cations (positively charged ions) are smaller than their parent atoms, while anions (negatively charged ions) are larger.
  4. Metallic Radius: Generally increases down a group and is larger for metals than nonmetals.
  5. Nonmetals: Tend to have smaller atomic radii compared to metals.

According to diagonal relationship

The diagonal relationship refers to similarities between certain pairs of elements that are diagonally positioned from each other on the periodic table. The most notable example is the diagonal relationship between beryllium (Be) and aluminum (Al), as well as boron (B) and silicon (Si).

These pairs share similarities in their properties due to comparable atomic sizes and charge-to-radius ratios. For example:

  1. Beryllium (Be) and Aluminum (Al): Both have similar sizes and often display analogous behavior in certain compounds.
  2. Boron (B) and Silicon (Si): These elements also exhibit similarities in some chemical properties.

According to Ionization energy and electron affinity

Ionization Energy:

  1. Trend Across Periods: Generally increases from left to right due to increasing effective nuclear charge, making it harder to remove electrons.
  2. Trend Down Groups: Generally decreases from top to bottom because electrons are farther from the nucleus in higher energy levels.

Electron Affinity:

  1. Trend Across Periods: Generally becomes more negative from left to right due to increased attraction for electrons by the higher effective nuclear charge.
  2. Trend Down Groups: Generally becomes less negative from top to bottom because electrons are added to higher energy levels, farther from the nucleus.

EVALUATION:  Discuss the properties of elements on the periodic table according to the following headings.

  1. Size
  2. Ionization energy
  3. Electron affinity.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively