DELL'ATOMO SI PARLAVA GIA' NELLA CIVILTA'GRECA
L'atomo non è più la più piccola parte della materia, come diceva Dalton, ma è formato da particelle subatomiche chiamate protoni, con carica positiva, elettroni con carica negative, neutre senza carica.
L'atomo ha un nucleo centrale in cui sono presenti protoni e neutroni. Il numero di massa che si indica con A indica la somma dei protoni e neutroni.
il Numero atomico che si indica con Z è la somma dei protoni, e in un atomo neutro corrisponde anche alla somma degli elettroni, e caratterizza l'atomo, cioè lo identifica. E' come se fosse il DNA dell'atomo, non esistono due atomi con lo stesso numero atomico. La tavola periodica degli elementi è stata costruita secondo un numero atomico crescente.
A-Z= NUMERO DI NEUTRONI
GLI ISOTOPI SONO ATOMI CHE HANNO STESSO NUMERO ATOMICO MA DIVERSO NUMERO DI MASSA, QUINDI STESSI PROTONI MA DIVERSI NUMERO DI NEUTRONI( VED, VIDEO ULTIMO)
Credits:
Creato con immagini di Hal Gatewood - "untitled image" • CDC - "This illustration, created at the Centers for Disease Control and Prevention (CDC), reveals ultrastructural morphology exhibited by coronaviruses. Note the spikes that adorn the outer surface of the virus, which impart the look of a corona surrounding the virion, when viewed electron microscopically. A novel coronavirus, named Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), was identified as the cause of an outbreak of respiratory illness first detected in Wuhan, China in 2019. The illness caused by this virus has been named coronavirus disease 2019 (COVID-19)." • CDC - "Produced by the National Institute of Allergy and Infectious Diseases (NIAID), in collaboration with Colorado State University, this highly magnified, digitally colorized scanning electron microscopic (SEM) image, reveals ultrastructural details at the site of interaction of two spherical shaped, Middle East respiratory syndrome coronavirus (MERS-CoV) viral particles, colorized blue, that were on the surface of a camel epithelial cell, colorized red." • CDC - "This image depicts Centers for Disease Control and Prevention (CDC) intern, Maureen Metcalfe, as she was using one of the agency’s transmission electron microscopes (TEM). The microscope’s screen was displaying a thin section of the variola virus, revealing some of the ultrastructural features displayed by this pathogenic organism, which is the cause of smallpox." • CDC - "Produced by the National Institute of Allergy and Infectious Diseases (NIAID), this highly magnified, digitally colorized scanning electron microscopic (SEM) image, revealed ultrastructural details at the site of interaction of numerous yellow colored, Middle East respiratory syndrome coronavirus (MERS-CoV) viral particles, located on the surface of a Vero E6 cell, which had been colorized blue." • Erwan Martin - "The LHC at CERN"