What is an Element?
An element is a pure substance that cannot be broken down into simpler substances by chemical means.
All elements are made up of only one kind of atom.
Some elements:
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Exist as single atoms (e.g., helium, neon).
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Exist as molecules (groups of atoms of the same kind joined together), e.g., oxygen (O₂).
Examples of Elements
Scientists have discovered about 115 elements.
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99 occur naturally.
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16 have been made by scientists.
First 20 Elements
| Number | Element | Number | Element |
|---|---|---|---|
| 1 | Hydrogen | 11 | Sodium |
| 2 | Helium | 12 | Magnesium |
| 3 | Lithium | 13 | Aluminum |
| 4 | Beryllium | 14 | Silicon |
| 5 | Boron | 15 | Phosphorus |
| 6 | Carbon | 16 | Sulphur |
| 7 | Nitrogen | 17 | Chlorine |
| 8 | Oxygen | 18 | Argon |
| 9 | Fluorine | 19 | Potassium |
| 10 | Neon | 20 | Calcium |
Key Points to Remember
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Elements are basic building blocks of matter.
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They contain only one type of atom.
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Elements can be solid, liquid, or gas at room temperature.