A neutral sodium atom, for example, contains 11 protons and 11 electrons. Atoms that gain extra electrons become negatively charged. This suggests that the charge on the rod affects the nearby environment so that charge in the electroscope "feels" its presence.
What happens is that an electric field is created by the charge on the rod. This electric field influences the distribution of charge on the electroscope. We made sparks fly across a gap between two metal spheres.
Electrons were transferred by a rotating belt on to one of the spheres. As described above, the charges create an electric field which spans the space between the two spheres. The electrons jump the gap and settle on the other sphere which is grounded.
Grounding has to do with establishing an electrical connection to the earth which has the effect of neutralizing the electrical charge on an object. The flow of electrons between spheres results in the spark we see. But do we actually see the electrons? No, what we see results from the electrons striking atoms in the air between the spheres.
The struck atoms become "excited" and when the atoms jump back to a deexcited state they emit light. That is what we see as the spark. We are able to attract a metal can or even a large delicately balanced wood plank with charges on a rubber rod. We explain this by noting, as we explained the electroscope, that the presence of charge creates an electric field. Atoms are electrically neutral because they contain equal quantities of positively charged protons and negatively charged electrons.
Electrons and protons have equal but opposite charges, so the result is no net charge. Three important particles make up atoms, and each has a different charge.
Neutrons possess no electric charge, as their name suggests. Protons and electrons are both charged but oppositely so. Protons have a positive charge of 1. The chemical elements are defined most simply by the number of protons they have. This is called their atomic number, and the periodic table is a sequential list of elements with increasing atomic numbers.
Hydrogen has an atomic number of one meaning one proton , helium has two, lithium has three and so on. Category: Chemistry Published: June 7, Atoms do not always contain the same number of electrons and protons, although this state is common. When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges the electrons and positive electric charges the protons.
The total electric charge of the atom is therefore zero and the atom is said to be neutral. In contrast, when an atom loses or gains an electron or the rarer case of losing or gaining a proton, which requires a nuclear reaction , the total charges add up to something other than zero. The atom is then said to be electrically charged, or "ionized". There is a major difference between the neutral state and the ionized state. In the neutral state, an atom has little electromagnetic attraction to other atoms.
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