General Informations

Name of the teacher : Jennifer. M. JobSubject : ChemistryTopic : Mendeleev’s periodic

law, Moseley’s periodiclaw and Modern periodic

table and details of the element Lithium

Unit : Periodic table and Chemical Bond

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LEARNING OUTCOMES

Remember : a) The pupil recalls group and period b) The pupil recognizes Mendeleev’s periodic law and

Moseley’s periodic law.

Understand : c) The pupil compares Mendeleev’s periodic law and Moseley’s periodic law.

Apply : d)The pupil applies the periodic law in new and unfamiliar situations.

Analyze : e) The pupil focusses the ideas-Mendeleev’s periodic law and Moseley’s law , atomic number, atomic mass, electron distribution etc.

Evaluate : f) The pupil judges the differences between periodic law of Mendeleev and Moseley.

Create : g) The pupil generate examples for elements to find out the details about them from the periodic table.

INTRODUCTION

• New discoveries and the knowledge gained about the structure of the atoms paved the way for a detailed study of the properties of elements.

• The studies conducted by moseley regarding the properties of the elements related to their position in the periodic table, finally proved that the basic properties of elements depend on their atomic number and note on their atomic masses

CONTENT

The modern periodic table, which we now use, is the improved version of Mendeleev’s periodic table. The properties of elements depend on their atomic numbers.

Mendeleev’s Periodic Law

• Properties of elements depends on their atomic masses.

• When the elements are arranged in the ascending order of their atomic masses it is seen that their properties are repeated at specific intervals.

Moseley modified Mendeleev’s periodic law accordingly

• When elements are arranged in the ascending order of their atomic numbers there is a repetition of their properties at fixed intervals.

• Properties of elements depends on their atomic numbers.

One Portion Of The Periodic Table1H

Hydrogen1

2He

Helium2

3Li

Lithium2, 1

4Be

Beryllium2, 2

5B

Boron2, 3

6C

Carbon2, 4

7N

Nitrogen2, 5

8O

Oxygen2, 6

9F

Fluorine2, 7

10Ne

Neon2, 8

11Na

Sodium2, 8, 1

12Mg

Magnesium2, 8, 2

13Al

Aluminium2, 8, 3

14Si

Silicon2, 8, 4

15P

Phosphorous2, 8, 5

16S

Sulphur2, 8, 6

17Cl

Chlorine2, 8, 7

18Ar

Argon2, 8, 8

19K

Potassium2, 8, 8, 1

20Ca

Calcium2, 8, 8, 2

There are 7 periods. There are 18 groups.

The Details of the Element - Lithium

Atomic number 3

Symbol Li

Name Lithium

Atomic mass 4

Electron distribution 2, 1

FOLLOW-UP ACTIVITY

Write the details of elements of elements Oxygen (O) and Carbon (C).

CONCLUSION

From this we came to a conclusion that the modern periodic table, which we now use , is the improved version of Mendeleev’s periodic table.