How are elements ordered in the periodic table?
By increasing atomic number.
AQA GCSE Combined Science: Trilogy (8464) — Chemistry — Foundation · 5.1.2.1
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How are elements ordered in the periodic table?
By increasing atomic number.
What is an element’s atomic number?
The number of protons in its nucleus.
How does the number of electrons in a neutral atom relate to its atomic number?
They are equal.
What happens to electron structures as atomic number increases across the periodic table?
Patterns in electron structure repeat.
Why is the periodic table called periodic?
Similar chemical properties recur at regular intervals.
What is a group in the periodic table?
A vertical column of elements.
What do elements in the same group have in common in their electron structure?
They have the same number of outer-shell electrons.
Why do elements in the same group tend to have similar chemical properties?
They have the same number of outer-shell electrons, which are mainly involved in chemical reactions.
What is a period in the periodic table?
A horizontal row.
What does an element’s period number indicate about its atoms?
The number of occupied electron shells.
How does atomic number change across a period?
It increases.
How is the number of electrons in a neutral atom related to its atomic number?
They are equal.
When does a new period begin in terms of electron shells?
When electrons begin to occupy a new outer shell.
For the first 20 elements, how many electrons can occupy each of the first three shells before electrons enter the fourth?
First shell: 2; second: 8; third: 8.