Atomic And Molecular Masses
Chapter Name : Some Basic Concepts Of Chemistry |
Sub Topic Code : 102_11_01_07_04 |
Topic Name : Atomic And Molecular Masses |
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Sub Topic Name : Formula Mass |
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Introduction
Formula mass is sum of the atomic masses of the atoms in a formula unit of the compound. It is used when a substance is ionic in nature and does not occur as a molecule alone but in a group. E.g. NaCl crystal lattice.
Pre-Requisites:
Mass, atom, element, compound, atomic mass, chemical formula
Activity:
Table Salt. Take a look at the smallest salt crystal under a magnifying glass.
Real Life Question:
What is the smallest particle of the table salt?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Formula | A formula is a concise way of giving information about an object or substance. |
| Formula mass | It is the sum of the atomic masses of all the atoms in a formula unit of the compound, whether molecular or not. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Salt, magnifying glass | Take a pinch of salt and break it down to the smallest possible particle. See it under a magnifying glass. |
Real life uses :
Obtaining the mass of ionic substances such as salt.
Places to visit :
Kitchen
Practical examples around us
| Examples | Explainations |
|---|---|
| Salt crystal | Salt occurs in crystals as the smallest unit. |
What you learn in Theory:
Formula mass is the sum of the atomic masses of all the atoms in a formula unit of the compound, whether molecular or not.
What you learn in Practice:
Not all substances have molecules occurring as smallest subunit.