sub-atomic particles for grade 7 matatag curriculum

parts of an atom for grade 7

1. atom

2. Discovering the structure of the atom In the fifth century B.C., the Greek Philosopher Leucippus and his student Democritus first made the proposal that Matter is composed of tiny particles that cannot be subdivided. Democritus gave this ultimate particles the name “ atomos ” which means uncuttable. Matter is composed of tiny indivisible particles called atoms. ATOM – is the smallest particle of an element.

3. ELECTRONS They are negatively charged particles that revolve around the nucleus in a fixed orbit. Unlike protons and neutrons, electrons are fundamental particles much smaller (almost 1800 times) in size than protons and neutrons. The standard symbol used for an electron is e or e – . British physicist J.J. Thomson discovered it in 1897. Electrons move so fast around the nucleus that their exact location within an atom cannot be accurately determined. When the number of negatively charged electrons equals the number of positively charged protons, the atom is neutral in charge.  

4. PROTONS Protons are positively charged particles found within a dense region at the center of the atom called the nucleus. They were discovered by Ernest Rutherford in the year 1917 and are denoted by the symbol p or p + . Protons consist of even smaller particles called quarks and gluons. Found tightly packed with the nucleus, they make up virtually all of the mass of an atom, along with the neutrons.

5. NEUTRONS They are also found within the nucleus along with the protons in a tightly packed manner. They were discovered by James Chadwick in the year 1932 and are denoted by the symbol n. Neutrons are neutral particles with no charge but have a substantial size and mass similar to a  proton .

6. DISCOVERY AND THEORIES OF AN ATOM

7. How do the characteristics of the plum-pudding model, bohr model and the Rutherford model help us understand the behavior of particles within atoms?

8. Plum-Pudding Model (J.J. Thomson, 1904): Describes the atom as a sphere of positive charge with negatively charged electrons embedded within it, like plums in a pudding. Helps us understand the existence of electrons within atoms.

9. Rutherford Model (Ernest Rutherford, 1911): Proposes that an atom consists of a small, dense, positively charged nucleus surrounded by electrons in empty space. Reveals that most of an atom’s mass is concentrated in the nucleus and that electrons orbit this nucleus.

10. Bohr Model (Niels Bohr, 1913): Suggests that electrons travel in fixed orbits around the nucleus and can jump between these orbits by absorbing or emitting energy. Introduces the idea of quantized electron energy levels, explaining the stability of atoms and the emission spectra of elements.

11. Key concepts: All matter is made up of tiny particles called atoms or molecules. Atoms are the fundamental building blocks of elements, while molecules consist of two or more atoms chemically bonded together. Particles are constantly in motion: ▪ In solids, particles vibrate in place. ▪ In liquids and gases, particles move from one location to another.

12. In solids, particles are closely packed with minimal space between them. In liquids and gases, particles have more space between them. As temperature increases, particle motion speeds up. Higher kinetic energy leads to faster vibrations and movement of particles.