AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
The periodic table: The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups. The table is called a periodic table because similar properties occur at regular intervals.
The modern periodic table orders elements by increasing atomic (proton) number, the number of protons in the nucleus.
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
The modern periodic table orders elements by increasing atomic (proton) number, the number of protons in the nucleus. This ordering places elements with similar chemical properties into vertical columns called groups. For example, Group 1 contains lithium, sodium and potassium, which all react vigorously with water and form 1⁺ ions. The arrangement is called periodic because similar properties recur at regular intervals as proton number increases. Reading across a period, properties change gradually, but moving down a group, behaviour repeats in a pattern. This structure allows chemists to predict the properties and reactions of an element from its position, rather than learning each element separately.
What earns the marks
- States that elements are arranged in order of increasing atomic (proton) number.
- Identifies vertical columns as groups and links them to similar chemical properties.
- Explains that the table is periodic because similar properties recur at regular intervals.
- Uses a named group, such as Group 1 or Group 7, to illustrate similar properties.
- Distinguishes atomic (proton) number from mass number when describing the ordering.
Common mistakes and how to put them right
Saying elements are arranged in order of relative atomic mass.
Put it right by stating that the modern table uses atomic (proton) number, which resolves earlier inconsistencies.
Confusing groups with periods.
Put it right by noting that groups are vertical columns and periods are horizontal rows.
Describing the table as periodic because it repeats every eight elements only.
Put it right by explaining that similar properties recur at regular intervals, not necessarily every eight.
Exam tips
- Quote atomic (proton) number explicitly rather than saying atomic number alone if the question asks for the modern ordering principle.
- When asked why the table is periodic, link the word to a repeating pattern of properties down a group.
- Use a specific group example to support your explanation, such as the reactivity trend in Group 1.
Try the lesson
The start of the The periodic table: The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups. The table is called a periodic table because similar properties occur at regular intervals. lesson, made from checked teaching notes for this specification point.
Have a go first
In the periodic table, what is the name given to a vertical column of elements?
Listen
The modern periodic table orders elements by increasing atomic (proton) number, the number of protons in the nucleus. This ordering places elements with similar chemical properties into vertical columns called groups. For example, Group 1 contains lithium, sodium and potassium, which all react vigorously with water and form 1⁺ ions. The arrangement is called periodic because similar properties recur at regular intervals as proton number increases. Reading across a period, properties change gradually, but moving down a group, behaviour repeats in a pattern. This structure allows chemists to predict the properties and reactions of an element from its position, rather than learning each element separately. A strong answer earns marks for these points. States that elements are arranged in order of increasing atomic (proton) number. Identifies vertical columns as groups and links them to similar chemical properties. Explains that the table is periodic because similar properties recur at regular intervals. Uses a named group, such as Group 1 or Group 7, to illustrate similar properties. A common slip: Saying elements are arranged in order of relative atomic mass. Instead, stating that the modern table uses atomic (proton) number, which resolves earlier inconsistencies. Exam tip: Quote atomic (proton) number explicitly rather than saying atomic number alone if the question asks for the modern ordering principle.
See it
Key words
Say what each word means before you turn the card.
Groups
Try answering aloud or in your head before turning the card.
Periodic table
Try answering aloud or in your head before turning the card.
Periodic
Try answering aloud or in your head before turning the card.
See every definition
- Groups
- Vertical columns in the periodic table containing elements with similar properties.
- Periodic table
- A table of elements arranged in order of atomic (proton) number so that elements with similar properties are in columns.
- Periodic
- Describes how similar properties occur at regular intervals in the table.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of The periodic table: The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups. The table is called a periodic table because similar properties occur at regular intervals.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge