Year 10 Science · Unit 2 · Lesson 22

The Big Bang and Formation of the Elements

Foundation Worksheet

Name

Date

Class

Learning Goals

Recall which elements formed in the Big Bang and which formed later in stars.
Sort elements and processes into where they were made in the Universe.
Describe the main evidence that supports the Big Bang model.

Warm Up

Fill the gap

Choose the correct word from the word bank to complete each sentence. Three words will NOT be used.

cooling oxygen uranium hydrogen microwave supernova iron helium fusion gravity

The Big Bang happened about 13.8 billion years ago in a hot, dense state that has been expanding and ever since. In the first few minutes the lightest element, , formed first, followed by and a trace of lithium. Heavier elements were not made in the Big Bang. Inside stars, nuclear joins light nuclei together and releases energy. Fusion in stars builds elements up to the group, near the peak in binding energy per nucleon. Some elements heavier than iron form in some explosions and neutron-star mergers through rapid neutron capture; evolved stars also make heavier elements through slow neutron capture. One key piece of evidence for the Big Bang is the cosmic background radiation that fills all of space.

Your Turn

Sort it!

Write each item into the best matching origin or process box. Heavy elements can have more than one production pathway, so classify the processes and sources rather than assigning each element a single birthplace.

Hydrogen Helium Lithium (trace) Carbon Oxygen Iron Gold (can form through s- and r-processes) Uranium (mainly r-process) First few minutes of the Universe Hydrogen fusing to helium Neutron-star mergers (an r-process site) Slow neutron capture (s-process) Rapid neutron capture (r-process) Asymptotic giant branch stars (s-process site) Star runs low on hydrogen

Made in the Big Bang

Made by fusion inside stars (up to iron)

Neutron-capture sources and processes beyond iron

Show What You Know

1. Which two elements made up almost all of the early Universe, and roughly what percentage was each (by mass)?

Recall 2 marks

2. Why is iron-56, ⁵⁶₂₆Fe, near the peak in binding energy per nucleon, and why does ordinary stellar fusion beyond the iron group generally stop releasing energy?

Recall 2 marks

Wrap Up

In one sentence, explain what people mean when they say "you are made of stardust".