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صفحة: 11
The Atomic Structure What is the atomic structure ? Its Greek name hints to the fact that it cannot be divided (“ a-tomos” in Greek means “ indivisible” ) . But is it really indivisible ? To describe the structure of the atom , scientists use a scientific model . A scientific model is a tangible model or image , through which we can describe a complex natural phenomenon and explain it . The Greek philosopher Democritus proposed a scientific model according to which the atom resembles a ball , and he claimed that it was impossible to divide it . This model was accepted also by scientists in the 16 century , about 2 , 000 years later . Over the years , science , technology and scientific thinking have continued to develop . Scientists have carried out experiments and the results have shown what can be learned about the atomic structure . They used the new knowledge they had gained to propose updated scientific models of the atomic structure . What is the modern scientific model of the atomic structure ? According to what we know today , at the center of the atom is a miniscule region referred to as the nucleus * , around which negatively charged particles form an "orbit" . These "orbiting" particles are referred to as electrons * . The nucleus consists of two kinds of particles : protons * , which have a positive electrical charge , and neutrons * , which have no electrical charge . The electrical charge of the nucleus is , therefore , positive . The area surrounding the nucleus , in which the electrons orbit , is referred to as the electron “ cloud ”* . Today we know that the protons and the neutrons making up the atom’s nucleus are made of even more elementary particles , but we will not be discussing them here . Nucleus – a miniscule , positively charged region at the center of the atom , consisting of protons and neutrons . Electrons – tiny particles surrounding the atom’s nucleus . which are negatively charged . Protons – particles within the atom’s nucleus , positively charged . Neutrons – particles within the atom’s nucleus , having no electrical charge ( neutral ) . Electron “ cloud ” – the region in which the electrons orbit the nucleus . The modern model of the atomic structure
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