"Method of Representing the Composition of Pure Substances" PPT courseware on the composition of matter

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"Method of Representing the Composition of Pure Substances" PPT courseware on the composition of matter

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Answer the questions based on the following substances:

①Water ②Oxygen ③Carbon dioxide ④Air

chemical symbol:__ __ __ __

Pure substance:_______

Mixture: ＿＿＿＿＿＿

learning target:

1. Master the concept of chemical formula;

2. Be able to tell the meaning of chemical formulas;

3. Develop a scientific attitude of seeking truth from facts;

4. Learn to look at problems from different angles;

1. Use chemical formulas to express the composition of pure substances

1. The concept of chemical formula: The composition of a pure substance is represented by a combination of element symbols and numbers. These formulas are called the chemical formula of the pure substance.

Such as: KMnO4 (potassium permanganate) compound

H2O (water) compound (or oxide)

CO2 (carbon dioxide) compound (or oxide)

Fe (iron) element

2. The meaning of chemical formula

1) Represents a certain substance

2) Indicate the elemental composition of this substance

3) Represents a particle of this substance

4) Indicate the structure of each particle (number of atoms contained or ratio of atoms)

Such as: CO2

1. Carbon dioxide is a substance;

2. Carbon dioxide is composed of carbon and oxygen elements;

3. 1 carbon dioxide molecule

4. One unit of carbon dioxide is composed of 1 carbon atom and 2 oxygen atoms (or the ratio of carbon atoms to oxygen atoms in carbon dioxide is 1:2).

4. How to read chemical formulas

(1) How to read elemental chemical formulas

a Noble gases and diatomic molecular gas elements - add the word "gas" after the element name.

He ——Helium O2 ——Oxygen

H2 ——Hydrogen N2 ——Nitrogen

b The rest read the name of the element directly.

Fe——Iron Cu——Copper

C——Carbon S——Sulfur

(2) How to read the chemical formula of a compound

a. The chemical formula name of a compound composed of two elements is generally read as "a certain chemical".

NaCl - sodium chloride. (Write first and read later, write later and read first)

MgO - magnesium oxide CaCl2 - calcium chloride

When reading the chemical formula of a compound, the number of atoms is read before the name of the element, but "1" is generally not read.

Fe3O4 ——ferric oxide CO2 ——carbon dioxide

CuO - copper oxide

If the element can form a variety of different substances, and in the chemical formulas of these substances, the number of atoms of the element is different, then the word "1" must be read.

CO2 - carbon dioxide, CO - carbon monoxide.

Class exercises

Use chemical formula and related numbers to express:

1 oxygen molecule＿＿＿ 2 hydrogen molecules＿＿

3 carbon dioxide molecules＿＿＿

4 phosphorus pentoxide molecules＿＿

Determine the meaning of the value "2" in the following chemical formula, and fill in its serial number on the corresponding horizontal line:

A, O2- B, H2SO4 C, 2CO2 D, 2Na+

⑴The number of molecules is __________;

⑵ What represents the number of ions is ＿＿;

⑶The number of charges carried by ions is ＿＿;

⑷The number of atoms contained in a molecule is ____;

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For more information about the PPT courseware "The Composition of Substances and the Representation of the Composition of Pure Substances", please click the "Composition of Substances PPT Representation of the Composition of Pure Substances" PPT tab.

"Method of Representing the Composition of Pure Substances" PPT Courseware on the Composition of Matter 2:

"Method of Expressing the Composition of Pure Substances" Composition of Matter PPT Courseware 2 1. Use chemical formulas to express the composition of pure substances 1. What is a chemical formula? Reading and Thinking Use a combination of element symbols and numbers to express the formula of a pure substance. What other chemical formulas do you know? ..

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Update Time: 2024-07-02

This template belongs to Chemistry courseware Hunan Education Edition Ninth Grade Chemistry Volume 1 industry PPT template

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