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Category: Chemistry

Level: SS1

Syllabus topic: SS1 Water and Chemical Bonding

Formula: H₂O

Description: Water is a polar molecule and essential for life.

📝 Exam Key Points

Bent (V-shaped) molecule with a bond angle of about 104.5° because oxygen has two lone pairs.
Polar covalent O–H bonds and hydrogen bonding explain its high boiling point (100 °C) and surface tension.
Hardness is caused by Ca²⁺/Mg²⁺ ions: temporary hardness is removed by boiling, permanent hardness by washing soda (Na₂CO₃).

Water

H₂O

Chemistry · SS1

Syllabus topic: SS1 Water and Chemical Bonding

Key Exam Points

Bent (V-shaped) molecule with a bond angle of about 104.5° because oxygen has two lone pairs.
Polar covalent O–H bonds and hydrogen bonding explain its high boiling point (100 °C) and surface tension.
Hardness is caused by Ca²⁺/Mg²⁺ ions: temporary hardness is removed by boiling, permanent hardness by washing soda (Na₂CO₃).

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