The document discusses elements and their properties. It asks questions about the most abundant elements in living organisms and Earth. It also asks about how different substances can be made from few elements, and what it means that everything is made of "stardust". Additionally, it discusses how scientists know atoms and molecules combine in ordered arrays, and why there are over 110 elements in the periodic table even though only 90 occur naturally on Earth. Finally, it asks questions about defining atoms and elements, why there are many substances, common metal properties, and what the periodic table of elements is.

1. Elements Review
Investigation 4
Mixtures and Solutions

2. Earth Elements
• What are the six most abundant elements in
living organisms? What percentage of an
organism is made of these six elements?
• What are the six most abundant elements in
the Earth? What percentage of Earth is made
of these six elements?
• How can so many different substances in the
world be made of so few elements?
• What does it mean when a person says
everything is made of stardust?

3. New Technologies
• How do scientists know that atoms and
molecules combine in well-ordered
arrays?
• Explain why the periodic table has over
110 elements when only 90 occur
naturally on Earth.

4. Summary: Elements
• What is an atom?
• What is an element?
• Explain why there are so many different
substances in the world.
• What properties do all metals have in
common?
• What is the periodic table of the elements?