Periodic Table IGCSE Chemistry: Complete Revision Guide

The periodic table sits at the heart of IGCSE Chemistry. Whether you're sitting Cambridge CAIE, Edexcel, or AQA, you will not get through your exam without a solid understanding of how the table is organised, what the trends mean, and how to apply that knowledge to unfamiliar questions.

This guide covers every major periodic table topic tested at IGCSE level. Work through it section by section, and you'll have a clear picture of what examiners expect and where students most often drop marks.

What is the periodic table in IGCSE Chemistry?

The periodic table is a structured arrangement of all known elements, ordered by increasing atomic number, in which elements with similar chemical properties appear in the same vertical column. It organises over 100 elements into a format that reveals patterns in structure, bonding, and reactivity.

According to Cambridge International Education, the periodic table is a required topic at every level of the IGCSE Chemistry syllabus. Understanding it unlocks a large portion of the marks available across Paper 1, Paper 2, and the extended theory papers.

The table is divided into periods (horizontal rows) and groups (vertical columns). The period number tells you how many electron shells an atom has. The group number tells you how many electrons are in the outermost shell, which directly determines how the element reacts.

How is the periodic table structured?

Understanding the layout is the first step. The table contains three broad regions: metals on the left and centre, non-metals on the upper right, and a zigzag boundary of metalloids in between.

Periods and what they tell you

There are seven periods in the full periodic table. IGCSE students focus primarily on Periods 1, 2, and 3. As you move across a period from left to right, the atomic number increases by one each time.

Across a period, the number of protons increases, which pulls electrons closer to the nucleus. This affects atomic radius, ionisation energy, and the type of bonding the element typically forms.

Groups and what they tell you

Groups are numbered 1 to 7, plus Group 0 (the noble gases). Elements in the same group share the same number of outer-shell electrons, which is why they have similar chemical properties.

For example, all Group 1 elements have one outer electron. They all react with water to produce a metal hydroxide and hydrogen gas. The reactions become more vigorous as you go down the group.

What are electron configurations at IGCSE?

Electron configuration describes how electrons are arranged in shells around the nucleus. At IGCSE level, you write these as a series of numbers separated by commas, showing how many electrons occupy each shell.

The rules are straightforward. The first shell holds a maximum of 2 electrons. The second and third shells each hold a maximum of 8. So sodium (atomic number 11) has the configuration 2, 8, 1.

Our tutors regularly see students lose marks by confusing the number of outer-shell electrons with the period number. Remember: the period tells you the number of shells, and the group tells you the number of outer electrons.

Electron configuration connects directly to how elements bond. Atoms with nearly full outer shells tend to gain electrons. Atoms with just one or two outer electrons tend to lose them. This drives ionic bonding, one of the most commonly tested concepts in IGCSE Chemistry.

What trends appear across periods and down groups?

Trend questions are among the most predictable in the IGCSE Chemistry exam. Examiners expect you to describe, explain, and sometimes compare trends using the correct chemical vocabulary.

Atomic radius

Atomic radius increases down a group because each new period adds an extra electron shell, pushing the outer electrons further from the nucleus.

Atomic radius decreases across a period from left to right. More protons pull the same number of shells inward more strongly, shrinking the atom.

Reactivity in metals

Reactivity in metals increases down a group. The outer electron is further from the nucleus and more shielded by inner shells, so it's lost more easily. Potassium is more reactive than sodium, which is more reactive than lithium.

Reactivity in non-metals

Reactivity in non-metals decreases down a group. The atom is larger, so it attracts electrons from other atoms less effectively. Fluorine is the most reactive non-metal; iodine is the least reactive of the common halogens.

Melting and boiling points

These trends are more complex and vary by group. In Group 1, melting points decrease down the group. In Group 7, melting and boiling points increase down the group. Knowing the direction of each trend and the reason behind it is what earns full marks.

What do you need to know about Group 1?

Group 1 elements are called the alkali metals. They include lithium, sodium, and potassium at IGCSE level. All three are soft, shiny metals that react vigorously with water and must be stored under oil to prevent contact with air and moisture.

The reaction with water follows a consistent pattern. The metal reacts to form a metal hydroxide and hydrogen gas. The reaction becomes faster and more energetic as you move from lithium to potassium.

Examiners frequently ask students to predict the behaviour of rubidium or caesium based on the trend they've described for lithium, sodium, and potassium. Practice this style of question. It rewards students who understand the pattern, not just those who have memorised individual facts.

Students working with IGCSE Chemistry tutors at Talimat often find Group 1 questions straightforward once they can link the trend to electron configuration. The further the outer electron is from the nucleus, the more easily the atom ionises, and the more reactive it becomes.

What do you need to know about Group 7?

Group 7 elements are the halogens: fluorine, chlorine, bromine, and iodine. They all have 7 outer-shell electrons and react by gaining one electron to form a singly charged negative ion.

The key trend to know is displacement. A more reactive halogen displaces a less reactive one from a solution of its salt. Chlorine displaces bromide ions from potassium bromide solution, turning it orange-brown. Bromine displaces iodide ions, turning the solution brown.

Physical state at room temperature is also tested. Fluorine and chlorine are gases. Bromine is a liquid. Iodine is a solid. As you go down the group, the melting and boiling points increase because the molecules become larger and intermolecular forces strengthen.

Halogen compounds appear across the IGCSE Chemistry syllabus, including in topics on ionic bonding, electrolysis, and organic chemistry. A secure understanding of Group 7 pays dividends across multiple exam questions.

What is Group 0, and why are noble gases unreactive?

Group 0 contains the noble gases: helium, neon, argon, krypton, and xenon. They are colourless, odourless gases at room temperature and are almost entirely unreactive under normal conditions.

Their stability comes from their electron configuration. Each noble gas has a full outer shell: helium has 2 electrons in its only shell, and all others have 8 in their outer shell. A full outer shell means no tendency to gain or lose electrons, so no chemical reactions occur under standard conditions.

IGCSE examiners use noble gases to test understanding of why a full outer shell equates to stability, and to contrast this with the behaviour of Group 1 and Group 7 elements.

How do metals and non-metals differ on the periodic table?

The majority of elements are metals. They occupy the left side and centre of the periodic table, including the transition metals in the middle block. Non-metals sit to the upper right.

The table below summarises the key differences tested at IGCSE level.

Property	Metals	Non-metals
Electrical conductivity	Good conductors	Poor conductors (except graphite)
Melting point	Generally high	Generally low
Appearance	Shiny, lustrous	Dull (most)
Malleability	Malleable and ductile	Brittle when solid
Oxide character	Basic oxides	Acidic oxides
Ion formed	Positive ions (cations)	Negative ions (anions)

These differences link directly to topics on bonding, structure, and reactivity. Metal oxides reacting with acids, for example, is a common six-mark question type that draws on this knowledge.

What are transition metals, and what makes them different?

The transition metals occupy the central block of the periodic table, between Groups 2 and 3. At IGCSE level, the key examples are iron, copper, zinc, and chromium.

Unlike Group 1 metals, transition metals are harder, have higher melting points, and are much less reactive with water. They also form coloured compounds and can act as catalysts in industrial processes.

A defining feature is that transition metals form ions with variable charges. Iron forms Fe2+ and Fe3+. Copper forms Cu+ and Cu2+. This variable valency is what produces the range of coloured compounds seen in solution chemistry and qualitative analysis questions.

According to Cambridge International, questions on transition metal properties and their use as catalysts appear regularly in both the core and extended papers. Iron as a catalyst in the Haber process is the most commonly cited example.

How can Talimat help with IGCSE Chemistry?

Periodic table questions reward students who understand patterns, not just those who memorise facts. That's a skill built through practice, explanation, and feedback. It takes time to internalise why trends work the way they do, and that's where good teaching makes a real difference.

Talimat's online tutoring platform connects students with specialist IGCSE Chemistry tutors through live, 1:1 sessions. Every tutor holds a relevant degree in their subject and has passed a 14-step vetting process.

Students in the Gulf working towards Cambridge IGCSE or Edexcel exams get a personalised study plan from day one, regular mock exam practice with written feedback, and access to 24/7 academic support. An Academic Consultant is assigned from the start to keep progress on track.

If your child is finding the periodic table or any other topic in IGCSE Chemistry difficult, contact us to match them with a specialist tutor in under 10 minutes.

Whether you're just starting Year 10 or sitting exams in a matter of weeks, the right support at the right time makes a measurable difference. Explore our blog for more IGCSE Chemistry revision guides, or speak to our team to find out more about A-Level tutoring when the time comes.