"Representation of Material Composition - Chemical Formula" Representation of Chemical Elements and Material Composition PPT Courseware 2

Description

"Representation of Material Composition—Chemical Formula" Representation of Chemical Elements and Material Composition PPT Courseware 2

learning target

1. Understand chemical formulas and their meanings, master the chemical formulas of some common substances, and understand how to write and read chemical formulas;

2. Master the relevant calculations of chemical formulas.

Knowledge points

1. Chemical formulas and writing of chemical formulas

1. Concept: Use a combination of element symbols and numbers to express the formula of material composition.

Such as: water H2O

Oxygen O2

carbon dioxide CO2

[Note] The composition of each pure substance is fixed, so there is only one chemical formula for a substance.

2. Meaning

chemical formula

Macro

①Indicates a substance

②Indicates the elemental composition of the substance

microscopic

①A molecule of substance

②Molecular composition of matter

Note: Consider whether the particles that make up matter are molecules or atoms.

2. Simple calculation of material composition

1. Calculate relative molecular mass

Understanding relative molecular mass

The meaning of H2O: A water molecule is composed of 2 hydrogen atoms and 1 oxygen atom.

True mass: The mass of 1 water molecule = the mass of 2 hydrogen atoms + the mass of 1 oxygen atom

Relative molecular mass: relative molecular mass of 1 water molecule = relative atomic mass of 2 hydrogen atoms + relative atomic mass of 1 oxygen atom

Therefore, the relative molecular mass of H2O = 1×2+16×1=18

Definition: The sum of the relative atomic masses of the atoms in the chemical formula is the relative molecular mass.

2. Calculate the mass ratio of the constituent elements of matter

The mass ratio between elements = the ratio of the sum of the relative atomic masses of each atom

Example: Find the mass ratio of iron element and oxygen element in Fe2O3.

Mass ratio of iron element and oxygen element in Fe2O3

Fe:O=(56×2):(16×3)=112:48=7:3

3. Calculate the mass fraction of an element in a substance

Mass fraction of an element = relative atomic mass of the element × number of atoms/relative molecular mass of the compound × 100.

Precautions:

①Mass fraction—expressed as a percentage

②Meaning: The mass fraction of a certain element contained in every 100 grams of the substance

Methods and techniques

The knowledge explained in this course is relatively large and fragmented. You must learn to systematically organize the content you have learned, break it into whole parts, connect the interrelated parts of each part, sort out each detail clearly, and form your own unique memory. The network, in this way, is not only conducive to the memory of knowledge, but also conducive to the transfer and application of knowledge.

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For more information about the PPT courseware "Chemical Elements and Substance Compositions Representation of Substance Compositions Representation of Chemical Formulas", please click the Representation of Chemical Elements and Substance Compositions PPT Representation of Substance Compositions by Representation of Chemical Formulas PPT tag.

"Representation of Substance Composition - Chemical Formula" Representation of Chemical Elements and Substance Composition PPT courseware:

"Representation of Chemical Formulas of Substance Compositions" PPT courseware on the representation of chemical elements and substance compositions Learning objectives 1. Master chemical formulas and their meanings, and be able to use chemical formulas to express the composition of substances. 2. Understand the meaning of relative molecular mass, and be able to use relative atomic mass to make related simplified...

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Update Time: 2024-10-19

This template belongs to Chemistry courseware Beijing Curriculum Reform Edition Ninth Grade Chemistry Volume 1 industry PPT template

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