Describe the trend in melting points across period 3 from sodium to argon.

Melting points increase from Na to Al (metallic bonding strengthens), Si has the highest (giant covalent), then drop sharply for P, S, Cl, Ar (simple molecular)

How does first ionisation energy change across a period, and at which points does it fall?

First ionisation energy generally increases across a period with drops at groups 3 and 6 due to sub-shell structure

Explain why there is a drop in first ionisation energy between groups 2 and 3.

The electron is removed from a higher energy p-subshell rather than an s-subshell, requiring less energy

Why is there a drop in first ionisation energy between groups 5 and 6?

The electron removed is from a paired orbital, where it experiences additional electron-electron repulsion, making it easier to remove

Edexcel A-Level Chemistry 9CH0

Atomic Structure and the Periodic Table

Topic overview Protons, neutrons, electrons and isotopes Relative atomic mass and the mass spectrum Ionisation energy and the evidence for sub-shells Orbitals and electron configuration Periodicity across a period and down a group

Bonding and Structure

Topic overview Ionic bonding Covalent bonding, dative bonding and the shapes of molecules Electronegativity, polarity and intermolecular forces Structure and properties

Redox I

Topic overview Oxidation numbers Oxidation, reduction, disproportionation and half-equations

Inorganic Chemistry and the Periodic Table

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Organic Chemistry I

Topic overview Formulae, homologous series and functional groups IUPAC nomenclature Types of organic reaction and structural isomerism Stereoisomerism and E/Z nomenclature Practical techniques in organic chemistry Alkanes, crude oil and combustion pollutants Radical substitution Alkenes, the double bond and hydrogenation Electrophilic addition, Markovnikov's rule and the test for an alkene Addition polymers and waste polymers Nucleophilic substitution of halogenoalkanes Rates of hydrolysis and the SN1 and SN2 mechanisms Classifying and oxidising alcohols Alcohols: practical techniques and the core practicals

Modern Analytical Techniques I

Topic overview Mass spectrometry Infrared spectroscopy and the characteristic absorptions Deducing functional groups from an infrared spectrum

Energetics I

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Kinetics II

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Organic Chemistry II

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Organic Chemistry III

Topic overview The structure of benzene and the evidence for it Electrophilic substitution of benzene Nitration, halogenation, Friedel-Crafts and phenol Amines: structure and basicity Reactions of amines and preparing them Amides and condensation polymers Amino acids, zwitterions and proteins Empirical and molecular formulae from analytical data Grignard reagents and multi-step synthesis Purification techniques and the aspirin preparation

Modern Analytical Techniques II

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Atomic Structure and the Periodic Table

Periodicity across a period and down a group

3 things to know
Papers 1 and 3

Overview

What periodicity means, how structure and bonding set the melting and boiling temperatures across periods 2 and 3, the rise in first ionisation energy across a period and its falls between groups 2 and 3 and groups 5 and 6, atomic radii across a period and down a group, and using logarithms, hand-held spectroscopes and weighted means with periodic data.

What you need to know

Answer each one before you reveal it.

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Key term

Explain how structure and bonding affect melting and boiling temperatures across periods 2 and 3.

Key term

What type of calculation is used to determine relative atomic mass from isotopic abundance data?

Key term

What is meant by periodicity?

Questions from this subtopic

Each one with the model answer underneath.

1
What is meant by periodicity?
Model answer
The repeating pattern of physical and chemical properties across different periods of the periodic table
2
Explain how structure and bonding affect melting and boiling temperatures across periods 2 and 3.
Model answer
Metals have high values due to metallic bonding, giant covalent structures have very high values, and simple molecular structures have low values
3
Describe the trend in melting points across period 3 from sodium to argon.
Model answer
Melting points increase from Na to Al (metallic bonding strengthens), Si has the highest (giant covalent), then drop sharply for P, S, Cl, Ar (simple molecular)
4
How does first ionisation energy change across a period, and at which points does it fall?
Model answer
First ionisation energy generally increases across a period with drops at groups 3 and 6 due to sub-shell structure
5
Explain why there is a drop in first ionisation energy between groups 2 and 3.
Model answer
The electron is removed from a higher energy p-subshell rather than an s-subshell, requiring less energy
6
Why is there a drop in first ionisation energy between groups 5 and 6?
Model answer
The electron removed is from a paired orbital, where it experiences additional electron-electron repulsion, making it easier to remove

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Atomic Structure and the Periodic Table

Bonding and Structure

Redox I

Inorganic Chemistry and the Periodic Table

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AAtomisation turns each element into gaseous atoms.

BIonisation energy removes electrons from the metal atoms.

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