Periodic table structure — KCSE Chemistry

KCSE Chemistry · 74 practice questions · 4 syllabus objectives

33 easy26 medium15 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Describe the arrangement of elements in the modern periodic table in terms of periods and groups

Explain the basis of Mendeleev's periodic law and the modern periodic law

Identify the position of metals, non-metals and metalloids in the periodic table

Periodic table structure

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easySHORT ANSWER3 marks

List the main characteristics that distinguish metals, non-metals, and metalloids in the periodic table. (3 marks)

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Part (a) — 3 marks

Metals are typically good conductors of heat and electricity (1 mk)

Non-metals are generally poor conductors and can be gases or brittle solids (1 mk)

Metalloids have properties intermediate between metals and non-metals, often being semiconductors (1 mk)

easySHORT ANSWER4 marks

State the primary basis for arranging elements in the modern periodic table and explain how it reflects periodic trends. (4 marks)

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Part (a) — 2 marks

Elements are arranged in order of increasing atomic number. (1 mk)

This arrangement reflects the number of protons in the nucleus of each element. (1 mk)

Part (b) — 2 marks

The arrangement shows a periodic repetition of properties such as electronegativity and atomic radius. (1 mk)

Elements in the same group exhibit similar chemical properties due to having the same number of valence electrons. (1 mk)

easySHORT ANSWER4 marks

List two key features of Mendeleev's periodic law and how they differ from the modern periodic law. (4 marks)

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Part (a) — 4 marks

Mendeleev's periodic law is based on the properties of elements being a periodic function of atomic mass. (1 mk)

The modern periodic law states that properties of elements are a periodic function of atomic number. (1 mk)

Mendeleev left gaps for undiscovered elements, predicting their properties based on trends. (1 mk)

The modern periodic table does not have gaps for undiscovered elements as it is based on atomic number. (1 mk)

Name the period and group in which the element with atomic number 12 is located in the modern periodic table. (2 marks)