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๐ฌ Think about it
Think of LEGO bricks — the simplest pieces you can't break into anything smaller. Elements are like that for matter. Hydrogen and oxygen are these simplest building blocks. Let's get to know them.
What are elements?
- Elements are pure substances that cannot be broken down further.
- Each element is made of identical particles called atoms.
- Atoms of one element differ from those of any other.
- They are the building blocks of all matter.
Example:
Gold, silver, sulfur, and carbon are all elements.
What is a molecule of an element?
- Atoms of most elements cannot exist on their own.
- Two or more atoms join to form a stable molecule.
- Two hydrogen atoms join to make one hydrogen molecule.
- Two oxygen atoms join to make one oxygen molecule.
How are elements classified?
- Elements can be metals or non-metals.
- Gold, silver, magnesium, iron, aluminium are metals.
- Carbon, sulfur, hydrogen, oxygen are non-metals.
- A few like silicon and boron are in-between, called metalloids.
Metals
Non-metals
Examples: gold, silver, magnesium, iron, aluminium.
Examples: carbon, sulfur, hydrogen, oxygen.
Mercury is a liquid metal at room temperature.
Bromine is a liquid non-metal at room temperature.
๐ก A step further
- Elements are classified into metals and non-metals.
- Gold, silver, magnesium, iron, and aluminium are metals.
- Carbon, sulfur, hydrogen, and oxygen are non-metals.
- Silicon and boron have in-between properties; they are metalloids.
๐ก A step further
- There are 118 known elements; most exist as solids.
- Eleven elements are gases at room temperature, all non-metals.
- Only two are liquids: mercury (metal) and bromine (non-metal).
- Gallium and caesium are solids that melt at around 30°C.
โ Test Yourself
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What is an element?
View Answer
A pure substance that cannot be broken into anything simpler. It's a basic building block of all matter. -
What is an atom?
View Answer
The identical tiny particle that an element is made of. Each element has its own kind of atom. -
How many elements are known today?
View Answer
118, and most of them are solids. -
Name the two elements that are liquid at room temperature.
View Answer
Mercury, which is a metal, and bromine, which is a non-metal. -
What are metalloids?
View Answer
Elements like silicon and boron with properties in between metals and non-metals.
Important Points
- Elements cannot be broken into simpler substances.
- Each element is made of its own identical atoms.
- Elements are classified as metals, non-metals, or metalloids.
Important Definitions
- Element — a pure substance that cannot be broken down into simpler substances.
- Atom — the identical tiny particle that an element is made of.
- Molecule — a stable particle formed when two or more atoms combine.
- Metalloid — an element with properties between metals and non-metals (e.g. silicon, boron).
๐ NCERT Question 8 — Is it possible for
Can a substance be both an element and a compound at the same time? Explain why or why not.
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๐ NCERT Question 11 — Write the names of
Name any two compounds made only from non-metals, and give two uses of each.
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