"Model of Atomic Structure" PPT

"Model of Atomic Structure" PPT

Part One: The Development History of Atomic Structural Models

1. Dalton Atomic Model

——Modern scientific atomism

All matter is composed of the smallest indivisible particles - atoms.

Atomic model: Atoms are solid, irreducible solid balls.

2. Thomson’s atomic model

Atoms are not the smallest particles that make up matter - Thomson discovered the electron (1897)

Electrons are negatively charged particles with a certain mass that are commonly found in various atoms.

Thomson's atomic model: An atom is a particle with an evenly distributed positive charge in which many electrons are embedded, neutralizing the charge, thus forming a neutral atom.

3. Rutherford’s atomic model

Rutherford and his assistants conducted the famous alpha particle scattering experiment

Experimental phenomenon: Use alpha particles to bombard gold foil. Most of the particles will pass through the gold foil directly, a few will only produce a small deflection, but a very small number of particles will bounce back.

Explanation: The alpha particle may be collided back by a nucleus with a large mass but a small volume. The nucleus is positively charged and is located at the center of the atom.

4. Bohr atomic model

The electrons perform high-speed circular motion around the nucleus in layers in a certain orbit in the space outside the nucleus.

Model PPT of atomic structure, part 2: structure of atom

Positive charge on the nucleus = Negative charge on the electrons

Thinking: What is the spatial position and relative size of the nucleus in the atom?

(1) The nucleus is located in the center of the atom, occupies a small volume of the atom, and is positively charged.

(2) The mass of an atom is mainly concentrated in the nucleus, and the mass of electrons outside the nucleus is very small.

(3), in the same atom:

Nuclear charge = Number of protons = Number of electrons outside the nucleus ≠ Number of neutrons

Atomic structure model PPT, the third part: summary:

1. Atoms are composed of a nucleus at the center of the atom and electrons outside the nucleus;

2. The nucleus of an atom is positively charged, and the electrons outside the nucleus are negatively charged;

3. The nucleus is very small, but almost contains the mass of the entire atom;

4. The electrons outside the nucleus have a very small mass and are layered around the nucleus and moving at high speed.

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