"Structure of Atom" The Mystery of Material Composition PPT Courseware 6

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"Structure of Atom" The Mystery of Material Composition PPT Courseware 6

Review questions

1. What are the definitions of molecules and atoms?

2. Characteristics of molecules and atoms?

3. What is the essence of chemical reaction?

In chemical reactions, molecules can be divided into atoms, but atoms cannot be further divided. So, can atoms be further divided using other methods?

In 1897, British scientist Thomson discovered electrons (from inside atoms), proving that atoms can be divided; Rutherford proposed the "nuclear model" of atomic structure, also called the "planetary model"

1. The composition of atoms

Nucleus

proton

neutron

extranuclear electrons

1 Electricity and power

1 proton carries one unit of positive charge;

1 electron carries one unit of negative charge.

The number of positive charges carried by the nucleus is called nuclear charge

2It can be concluded from the table:

(1) The number of protons is not necessarily equal to the number of neutrons, and atoms do not necessarily contain neutrons;

(2) The necessary particles that make up an atom are protons and electrons. What determines the type of atom is the number of protons in the nucleus, which is essential.

Reasons why atoms are not electrically conductive:

Since the electric charge of the nucleus is equal to the electric charge of the electrons outside the nucleus, but the electric properties are opposite, the whole atom is not electrical.

The masses of different atoms vary and can be measured accurately with modern scientific instruments. like:

The mass of a hydrogen atom is: 1.67×10-27�,

The mass of an oxygen atom is: 2.657×10-26�,

The mass of an iron atom is: 9.288×10-26�.

Such a small number is very inconvenient to write, remember and use, just like using tons as a unit to express the mass of a grain of rice or wheat. Can it be expressed in a way that is easy to write, remember and use? What about the mass of an atom?

2: Relative atomic mass (P56)

mass of atom

The mass of a carbon atom is: 1.993×10-26 kg

The mass of an oxygen atom is: 2.657×10-26 kg

The mass of a hydrogen atom is: 1.67×10-27 kg

1. Definition: Taking 1/12 of the mass of a C-12 atom as a standard (actually the mass of a proton or a neutron), the value obtained by comparing the mass of other atoms with it is used as the relative atomic mass of this atom. . (symbol is Ar)

2. Definition formula: Relative atomic mass Ar of a certain atom

The actual mass of the atom (kg)

= The actual mass of an atom (kg)/The actual mass of a carbon atom (kg) × 1/12

Actual mass of a carbon atom (kg) × 1/12

Notice:

a. Relative atomic mass is a ratio and not the actual mass.

b. The international system of units is 1.

Class exercises

1 The relative atomic mass of an iron atom is ( )

A 56g B 56

C 9.288 × 10-26 Kg D 1/56

2 The essential particle that makes up all atoms is ( )

A proton B proton electron

C proton neutron electron D proton neutron

3. Russian scientists recently synthesized an atom of an element with a nuclear charge of 114. The approximate relative mass of the atom was determined to be 289, so the number of neutrons is ________.

4. The smallest particle in a chemical change is ( )

A. Atom B. Molecule C. Proton D. Neutron

5. It is known that the mass of 1 C-12 atom is akg, then the relative atomic mass of another atom with an actual mass of b kg is ( )

A.12b/a kg B.12b/a C.12a/b D.12a/b kg

6. The number of protons in a radon atom is 86 and the number of neutrons is 136. The number of electrons outside the nucleus of this radon atom is ( )

A.50 B.86 C.136 D.222

3. Arrangement of electrons outside the nucleus

1. The electrons outside the nucleus are arranged in layers

It was found that the minimum number of electrons outside the nucleus is 1, and the maximum number is 7.

(K L M N O P Q or 1 2 3 4 5 6 7 )

2. Schematic diagram of atomic structure

3. The rules of electron arrangement outside the nucleus (2n2)

The number of electrons in the first layer shall not exceed 2, and the number of electrons in the outermost layer shall not exceed 8.

4. The chemical properties of elements are closely related to the number of electrons in the outermost shell of the atom.

1. What determines the chemical properties of elements is ( )

A Number of protons B Number of outermost electrons C Number of neutrons D Atomic weight

2. Atoms and ions of the same element must have the same ( )

A The number of nuclear charges B The number of electron shells C The number of electrons in the outermost shell D The electric charge

3. There are 3 electron shells outside the nucleus of a certain element, and there is 1 electron in the outermost shell. The nuclear charge of the element is ( )

A 5 B 11 C 1 D 18

4. According to the schematic diagrams of the four particle structures, which of the following statements is correct ( )

①They all have electric charge ②They all have stable structures ③The electron arrangement outside their core is the same ④They belong to different kinds of elements

A①② B②③ C②④ D③④

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"Structure of Atom" The Mystery of Material Composition PPT Courseware 5:

"The Structure of Atoms" The Mystery of Material Composition PPT Courseware 5 Learning Objectives 1. Understand the structure of atoms and know the microscopic composition of atoms. 2. Understand the arrangement of electrons outside the nucleus and the formation process of ions. 3. Know the concept and calculation formula of relative atomic mass.

"Structure of Atom" The Mystery of Material Composition PPT Courseware 4:

"Structure of the Atom" The Mystery of the Composition of Matter PPT Courseware 4 Observe the table (Table 4-2) and think about the following questions: 1. What are the differences between different types of atoms? Different atoms have different numbers of protons, neutrons, and electrons. 2. All atoms are composed of protons, neutrons, and electrons..

"Structure of Atom" The Mystery of Material Composition PPT Courseware 3:

"Structure of the Atom" The Mystery of the Composition of Matter PPT Courseware 3 Knowledge Review In the experiment of decomposing hydrogen peroxide to produce oxygen, hydrogen peroxide ____ breaks into hydrogen ____ and oxygen ____. The text expression of this reaction is: ______________. It can be seen that the molecules are very small but in chemical reactions...

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Update Time: 2024-10-04

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